P EVALUATION OF APID TOOLING FOR ELECTRIC DISCHARGE...

PRODUCTION AND EVALUATION OF RAPID TOOLING FOR ELECTRIC DISCHARGE

MACHINING USING ELECTROFORMING AND SPRAY METAL DEPOSITION TECHNIQUES

BY

RICKY BLOM

Submission for Master of Engineering (Research) School of Mechanical, Medical and Manufacturing Engineering

Queensland University of Technology

School of Mechanical, Medical and Manufacturing Engineering

February 2005

ii

ACKNOWLEDGMENT

Thank you to Associate Professor Prasad K.D.V. Yarlagadda and Dr R. Mahalinga-

Iyer for your support and guidance throughout the duration of the project. Also thank

you to all other staff at Queensland University of Technology that assisted in the

completion of this research.

Thanks to the staff at Queensland Manufacturing Institute and QMI Solutions with

special thanks to Dr Periklis Christodoulou and Geoff Wakeley for their help and

guidance while conducting the research and experiments.

The help from the Rapid Prototyping and Tooling staff at QMI Solution and

Concentric AMF was invaluable and the experiments would not have been possible

without their help.

Additional thanks goes to Steve Smith at Romar Engineering for assistance with the

electroforming process and producing the electroformed shells. Thank you also to

Ben Grams at Bocar Engineering for the production of the spray metal electrode

shells.

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ABSTRACT

To survive in today’s manufacturing environments companies must push the

standards of accuracy and speed to the highest levels possible. Electro Discharge

Machining (EDM) has been used for over 50 years and recent developments have

seen the use of EDM become much more viable. The goal of this research is to

produce and evaluate electrodes produced by different manufacturing methods.

The use of electroforming and spray-metal deposition has only recently become viable

methods of producing usable rapid tooling components. The speed and accuracy as

well as the cost of manufacture play a vital role in the tool and mould manufacturing

process. Electroforming and spray-metal deposition offer an alternate option to

traditional machining of electrodes.

Electroforming is one method of producing electrodes for EDM. The fact that

electroforming can be used to produce multiple electrodes simultaneously gives it the

advantage of saving on costs when multiple electrodes are needed. Spray-metal

deposition offers another alternative that is much cheaper and relatively faster to

manufacture.

The used of these non-traditional manufacturing methods in this research are

compared to the performance of traditional solid electrodes in terms of machining

time, material removal rate, tool wear rates and surface roughness at several standard

machining settings.

The results of this research are presented in this thesis along with conclusions and

comments on the performance of the different methods of electrode manufacture. The

major findings of the research include the solid electrodes performed better than the

electroformed electrodes in Material Removal Rate (MRR), Tool Wear Rate (TWR),

and Surface Roughness (Ra) at all machine settings. However it was found that the

production cost of the solid electrodes was six times that of the electroformed

electrodes.

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The production of spray metal electrodes was unsuccessful. The electrode shell walls

were not an even thickness and the backing material broke through the shell making

them unusable.

It is concluded that with further refinements and research, electroforming and spray

metal processes will become an extremely competitive method in electrode

manufacture and other rapid tooling processes.

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DECLARATION

“The work contained in this thesis has not been previously submitted for a degree or

diploma at any other higher education institution. To the best of my knowledge and

belief, the thesis contains no material previously published or written by another

person except where due reference is made.”

Signed ………………………

Date …………………………

vi

TABLE OF CONTENTS

ACKNOWLEDGMENT................................................................................................ii

ABSTRACT................................................................................................................. iii

DECLARATION ...........................................................................................................v

TABLE OF CONTENTS..............................................................................................vi

LIST OF FIGURES ................................................................................................... viii

LIST OF TABLES..................................................................................................... xiii

PUBLICATIONS.........................................................................................................xv

1.0 INTRODUCTION ...................................................................................................1

1.1 AIMS AND OBJECTIVES..........................................................................................3

1.2 METHODOLOGIES ..................................................................................................3

2.0 LITERATURE REVIEW AND BACKGROUND .................................................5

2.1 RAPID PROTOTYPING AND TOOLING .....................................................................5

2.2 ELECTROFORMING ................................................................................................7

2.3 SPRAY DEPOSITION................................................................................................9

2.4 EDM...................................................................................................................10

2.5 LITERATURE REVIEW ..........................................................................................12

3.0 EXPERIMENTAL DESIGN ................................................................................16

4.0 EXPERIMENTAL PROCEDURE .......................................................................20

5.0 EXPERIMENTAL RESULTS .............................................................................26

5.1 EXPERIMENT 1 ....................................................................................................26

5.1.1 Solid Electrodes compared to Electroformed Electrodes ...........................27

5.1.2 Work pieces machined by different electrodes. ..........................................31

5.2 EXPERIMENT 2 ....................................................................................................35


5.2.2 Work pieces machined by different electrodes ...........................................38

5.3 EXPERIMENT 3 ....................................................................................................41



5.4 EXPERIMENT 4 ....................................................................................................47



5.5 EXPERIMENT 5 ....................................................................................................51


vii


5.6 EXPERIMENT 6 ....................................................................................................58



5.7 SUMMARY OF ALTERNATIVE ELECTRODE MANUFACTURE AND PERFORMANCE

COMPARISON ............................................................................................................62

5.7.1 Detailed Failure Investigation of Spray Metal Electrodes..........................63

5.7.2 Cost Comparison.........................................................................................66

5.7.3 Performance Comparison of Manufacturing Methods ...............................69

6.0 CONCLUSIONS ..................................................................................................76

BIBLIOGRAPHY........................................................................................................79

viii

LIST OF FIGURES

Figure 2.1 – Electroforming Process .............................................................................8

Figure 2.2 – Spray Metal Deposition Process................................................................9

Figure 2.3 – Sodick Mould-Maker 3 NF40 .................................................................11

Figure 4.1 – SLA Electrode Master Patterns ...............................................................21

Figure 4.2 – Electrode grid measurements ..................................................................21

Figure 4.3 - Electrode Measurements before Experiment ...........................................22

Figure 4.4 - Electrode Measurements after Experiment ..............................................23

Figure 4.5 - Material removed from the electrode during the experiment...................24

Figure 5.1(a) – Base Electrode Wear Experiment 1 - Solid Electrode ........................28

Figure 5.1(b) – Base Electrode Wear Experiment 1 - Electroformed Electrode .........28

Figure 5.2 – Damage and excessive wear of Electroformed Base Electrode (EB1)....29

Figure 5.3 – Casting Inclusion and Electrode Wear ....................................................30

Figure 5.4 – Machining of triangle work piece in experiment 1 .................................31

Figure 5.5 – Failed Electroformed Electrode and Experiment 1 Work Piece .............31

Figure 5.6 – Electroformed Base Electrode for Experiment 1.....................................35

Figure 5.7 – Electroformed Base Electrode.................................................................36

Figure 5.8 – Electroformed cone electrode – Experiment 2 ........................................37

Figure 5.9 – Electroformed triangle electrode – Experiment 2 ...................................38

Figure 5.10 – Electroformed Base Electrode – Experiment 3 .....................................43


Figure 5.12 – Electroformed Cone Electrode – Experiment 5.....................................55

Figure 5.13 – Measurements of the different performances of Experiment 4 and

Experiment 5........................................................................................................55


Figure 5.15 – Defective spray metal shells ..................................................................63

Figure 5.16 – Sectional Views of Spray Metal Electrodes showing wall thicknesses 64

Figure 5.17 – Visual Surface Roughness comparison between Spray Metal (left) and

Solid Machined Electrodes (right) .......................................................................65

Figure 5.18 – Surface imperfection in the spray metal shells......................................66

Figure 5.19 – Machining time Comparison .................................................................70

Figure 5.20 – MRR Comparison..................................................................................71

Figure 5.21 – MRR Comparison for research by Leu, Yang and Yao [15].................72

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Figure 5.22 – TWR Comparison..................................................................................74

Figure 5.23 – TWR Comparison for research by Leu, Yang and Yao [15].................75

Figure A.1 - Cone Electrode Wear Experiment 1 - Solid Electrode............................85

Figure A.2 - Cone Electrode Wear Experiment 1 - Electroformed Electrode .............86

Figure A.3 – Triangle Electrode Wear Experiment 1 - Solid Electrode......................87

Figure A.4 – Triangle Electrode Wear Experiment 1 - Electroformed Electrode .......88

Figure A.5 – Base Work Pieces Machined by Solid Electrode compared to

Electroformed Electrode - Solid Electrode Work Piece ......................................89


Electroformed Electrode - Electroformed Electrode Work Piece........................90

Figure A.7 – Cone Work Pieces Machined by Solid Electrode compared to




Figure A.9 – Triangle Work Pieces Machined by Solid Electrode compared to




Figure A.11 – Base Electrode Wear Experiment 2 - Solid Electrode..........................95

Figure A.12 – Base Electrode Wear Experiment 2 - Electroformed Electrode ...........96

Figure A.13 – Cone Electrode Wear Experiment 2 - Solid Electrode .........................97

Figure A.14 – Cone Electrode Wear Experiment 2 - Electroformed Electrode ..........98

Figure A.15 – Triangle Electrode Wear Experiment 2 - Solid Electrode....................99

Figure A.16 – Triangle Electrode Wear Experiment 2 - Electroformed Electrode ...100


Electroformed Electrode Experiment 2 - Solid Electrode Work Piece..............101


Electroformed Electrode Experiment 2 - Electroformed Electrode Work Piece

............................................................................................................................102





............................................................................................................................104

x





............................................................................................................................106

Figure A.23 – Base Electrode Wear Experiment 3 - Solid Electrode........................107

Figure A.24 – Base Electrode Wear Experiment 3 - Electroformed Electrode .........108

Figure A.25 – Cone Electrode Wear Experiment 3 - Solid Electrode .......................109

Figure A.26 – Cone Electrode Wear Experiment 3 - Electroformed Electrode ........110

Figure A.27 – Triangle Electrode Wear Experiment 3 - Solid Electrode..................111






............................................................................................................................114





............................................................................................................................116





............................................................................................................................118









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............................................................................................................................126





............................................................................................................................128





............................................................................................................................130











............................................................................................................................138





............................................................................................................................140





............................................................................................................................142

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............................................................................................................................150





............................................................................................................................152





............................................................................................................................154

xiii

LIST OF TABLES

Table 3.1 – Machine Settings or Finishing, Semi-Roughing and Roughing Cuts.......17

Table 3.2 – Actual Settings or Finishing, Semi-Roughing and Roughing Cuts ..........17

Table 4.1 – CMM Coordinate measurements of the electrode height .........................22

Table 4.2 – Mass measurements and calculations taken from experiments ................24

Table 4.3 – Measurements of Ra from the Taylor Hobson Surtronic ..........................25

Table 5.2 – Machining Time for Experiment 1 ...........................................................33

Table 5.3 – Material Removal Rate for Experiment 1.................................................34

Table 5.4 – Tool Wear Rate for Experiment 1.............................................................34

Table 5.5 – Average Surface Roughness Ra μm, Experiment 1 ..................................35

Table 5.6 – Change in Mass for Experiment 2 ............................................................39

Table 5.7 – Machining Time for Experiment 2 ...........................................................40

Table 5.8 – Material Removal Rate for Experiment 2.................................................40

Table 5.9 – Tool Wear Rate for Experiment 2.............................................................41

Table 5.10 – Average Surface Roughness Ra μm, Experiment 2 ................................41

Table 5.11 – Change in Mass for Experiment 3 ..........................................................45

Table 5.12 – Machining Time for Experiment 3 .........................................................46

Table 5.13 – Material Removal Rate for Experiment 3...............................................46

Table 5.14 – Tool Wear Rate for Experiment 3...........................................................47














xiv




Table 5.31 – Manufacturing Cost Comparison of different Processes ........................68

Table 5.32 – Machining Time Comparison for different electrodes at various settings

..............................................................................................................................69

Table 5.33 – MRR Comparison for different electrodes at various settings ...............71

Table 5.34 – MRR Comparison for different electrodes at various settings for research

by Leu, Yang and Yao [15]..................................................................................72

Table 5.35 – TWR Comparison for different electrodes at various settings ...............73

Table 5.36 – TWR Comparison for different electrodes at various settings for research

by Leu, Yang and Yao [15]..................................................................................74

xv

PUBLICATIONS

• Ricky Blom, Prasad KDV Yarlagadda and R. M. Iyer, “Evaluation of Rapid

Tooling for Electric Discharge Machining Using Electroforming and Spray

Metal Deposition Techniques”, Proc. of International Conference on

Manufacturing and Management 2004, India, 8-10 December 2004 [In Press].

1

1.0 INTRODUCTION

To compete in today’s industry environment, companies must keep up with the

leading technologies and processes and also push the boundaries and develop new and

improved products and processes. The Manufacturing Industry is an area where time,

efficiency and accuracy are the major driving forces behind innovation and research.

The most competitive companies are those who continually reduce process times,

increase efficiency and improve accuracy. Rapid Prototyping and Tooling is an area

that has and is continuing to reduce production time and increase efficiency and

accuracy in developing and manufacturing prototypes compared to traditional

prototype manufacture.

The main function of Rapid Prototyping (RP) is to give the manufacturing the needed

confidence to go on to tooling and mass manufacture of the product they have

designed. Once the product has met the design criteria through RP it is then needed to

meet the functional criteria and that is where Rapid Prototyping has developed and

evolved into Rapid Tooling. RP is an extremely useful process but it cannot always

provide the manufacturer with a functional prototype in the material of choice.

Rapid Tooling can provide this solution giving the manufacturer a functional

prototype in the material of choice and that allows functional testing to be done on the

product. The use of Rapid Tooling means a reduction in the time-to-market for a

product and also better testing to meet functional criteria. Rapid Tooling is also

useful in helping start production and getting the product into the market, while the

more expensive and durable traditional tool is being produced for the mass

manufacture of the product. Therefore the competition lies in researching possible

ways to increase the effectiveness of Rapid Tooling and reducing the time and cost of

getting the customers product to market.

Electro-Discharge Machining (EDM) is a manufacturing process that has been

affected by developments in Rapid Prototyping and Tooling. EDM is commonly used

by toolmakers for complex injection moulds, punch dies and cavities made from

hardened tool steels. EDM is ideal for materials and complex shapes that traditional

machining processes are unable to perform.

2

In die and mould production, the EDM cycle can account for 25 to 40% of the tool

room lead-time [1, 2]. The electrode production represents over 50% of the cost and

time of an EDM operation [2]. The goal is to reduce the time and cost of the EDM

cycle and to do this, alternate methods of electrode production is a key area of

research.

Since conception EDM electrodes have been manufactured from solid conductive

metals including copper and tungsten, and also from non-metals mainly graphite.

Using traditional machining operations in producing complex electrodes from solid

copper or graphite may require the production of several smaller electrodes and

joining them together, or running several machining cycles to get the required cavity

or shape. Therefore increasing the complexity of the electrode increases the electrode

production time and also increases the machining time if several machining cycles are

required. Investigation into alternate methods of electrode production is required to

reduce cost and time.

To gain a good comparison of the various electrode manufacturing methods, the

experiments include the use of Electroformed Copper, Copper Spray-deposition and

Traditional Solid Machined Copper Electrodes tested under several machining

conditions.

Electroforming is a process that can be controlled to a high degree and can operate

with precision and reliability. Electroforming can be employed to produce electrodes

with complex shapes that in the past would require the use of several conventional

techniques that might include machining, pressing and welding to manufacture a

similar electrode.

The other manufacturing process used in attempts to produce copper electrodes is

Spray Deposition or Spray Metal Deposition as it is also named. Spray metal

deposition has been used to produce moulds for many different moulding processes.

It is possible for the moulds to be manufactured quickly and inexpensively for those

processes [4-9]. As a different rapid prototyping technology and quick production

technology, spray metal tooling is used in a flexible system for producing small

3

numbers of parts. Spray metal deposition is normally used to produce moulds but in

this project it is used to spray into a mould to produce the electrode shells.

When comparing the different electrode manufacturing methods, the machining

conditions include a roughing setting, semi-roughing setting and a finishing setting.

The performance of the EDM process is measured with respect to machining rate or

Material Removal Rate (MRR), electrode wear (TWR), and surface finish of the work

piece (Ra).

The design of the electrodes evolved from previous research in the design and use of

electroformed electrodes. The tool used by Subramanian [3] was found to produce

excess wear on the protruding surfaces and very little wear on the cavities. Therefore

it was decided to do the tests using separate portions of similar design. The tools

developed include a simple conical shape, a triangular protrusion and a more complex

shape that would be almost impossible to machine a similar cavity. The simple and

complex designs are used to compare the various manufacturing methods.

1.1 AIMS AND OBJECTIVES

In the proposed research an attempt will be made to investigate the following:

(a) Testing the viability of electroformed copper electrodes for EDM by

conducting electrode wear studies,

(b) Testing the performance of an electroformed copper electrode in comparison

to a machined copper electrode, based on tool wear and economy of tool

manufacture,

(c) Study the effect of texture of the EDM tool on the work piece material, and

(d) Developing Rapid Tooling for EDM and injection moulding by using Spray

Metal Deposition technique [18].

1.2 METHODOLOGIES

This project involves the following steps:

• Development of CAD models of Electrodes

• Rapid prototyping and tooling to produce electrode master patterns,

4

• Electroforming negative tool to produce copper shells for electrodes, and

backfilling to give the shell support,

• Machining of Solid Copper Electrodes for comparison to alternatively

produced electrodes,

• Production of Spray-metal copper shells for electrodes,

• Testing Electrodes comparing Material Removal Rate (MRR), Tool Wear Rate

(TWR) and Surface finish for the different production methods,

• And evaluating results and developing conclusions.

The thesis includes a literature review in Chapter 2 where the technologies and

processes involved in the research are documented, followed by the outline of the

Experimental Design and Procedure in Chapters 3 and 4 used to collect the required

information and data for analysis. Chapter 5 gives the analysis and description of the

information and data collected during the experiments. Comments are made on the

comparison of the performance of the different electrode manufacturing methods and

machine settings. The conclusions are then summarised in Chapter 6.

5

2.0 LITERATURE REVIEW AND BACKGROUND

The tremendous advancements in EDM technology have been achieved for more than

50 years through the collective efforts of many dedicated engineers from some of the

worlds leading institutions and research centres. The research fields mainly cover

EDM control systems and EDM technology. EDM control system includes the servo

control unit and the parameters that control the system. EDM technology covers the

machine abilities and electrode research.

2.1 RAPID PROTOTYPING AND TOOLING

Rapid Prototyping (RP) and tooling is a continuation from three-dimensional CAD

modelling. RP uses the CAD data to produce layer information that is fed into RP

machines to produce a three dimensional solid model from a chosen process and

material. Common RP processes include Stereolithography (SL), Selective Laser

Sintering (SLS), Laminated Object Manufacturing (LOM) and Fused Deposition

Modelling (FDM). The majority of RP processes involve the conversion of the CAD

data into cross-sectional information and the model is built layer-by-layer.

In the production of EDM electrodes many RP processes have been previously used.

The most promising process involves the use of stereolithography and producing

models as either positive or negative master patterns. Stereolithography (SL) uses

information from a computer generated three-dimensional model to produce a solid

three-dimensional model from various types of laser-curing polymer resins. The

Stereolithography Apparatus builds the three-dimensional solid model layer by layer.

The computer file is broken down to layers and the SLA reproduces the layer on the

surface of the resin. The part is then lowered by the relative layer thickness, and the

process is repeated until the completed model is produced. The Stereolithography

Apparatus used is developed and marketed by 3D Systems Inc, Valencia, California,

USA. The machines produce models with high detail and accuracy and have the

ability to produce multiple parts simultaneously.

Using the positive master pattern is termed as “Direct Electrode Manufacture” in that

the SL pattern is plated with a conductive material and used as the electrode.

6

Alternatively, using the SL pattern as a negative and removing the plated shell is

termed as “Indirect Electrode Manufacture”.

Research in the area of Direct Electrode Manufacturing process includes work from

Arthur et al. [10-14] and Leu et al. [15]. Results using the direct manufacturing

method have shown advantages in that the electrodes are comparable to traditional

solid electrodes in finishing, semi-roughing and roughing machine settings and

electrode production time is reduced as large quantities of electrodes can be produced

simultaneously. The results also concluded disadvantages including the possibility of

non-uniform distribution of electrodeposited material resulting in unknown plating

thickness, EDM machining time is quite high, the SL master pattern is sacrificial and

the electrodes are prone to premature failure if the plating thickness is less than 180

μm.

Alternatively the area of Indirect Electrode Manufacture has been researched and

developed by Jensen and Hovtun [16], Rennie et al. [17] and Yarlagadda et al. [3, 18,

19]. Advantages for using indirect electrode manufacture include relatively low

manufacturing cost, multiple electrodes can be produced simultaneously, the master

pattern can be reused multiple times and the electrodes can be manufactured to high

accuracy and quality. Jensen and Hovtun were also able to show that the performance

is comparable to solid electrodes.

Jensen and Hovtun [16] found disadvantages that include unacceptably high wear

rate, poor accuracy, long process time and internal details can be problematic. Rennie

et al. [17] provided similar disadvantages in that narrow internal cavities are not

plated to the same thickness as external features and failure still occurs with excess

wear and uneven material distribution. Yarlagadda et al. indicated that different

sections of the tool performed more work than other sections, triangular protrusions

had split and tool failure occurred and course machining can deform the tool.

7

2.2 ELECTROFORMING

Electroforming uses electro-deposition of a metallic coating to a mould to produce a

negative copy, which is a hollow shell that is removed from the pattern as the finished

product, or the metallic coating is added to the pattern to produce a platted positive

product on the surface of the pattern. The process is shown in Figure 2.1.

First a mould is produced from the master pattern to be copied. The mould may consist

of a non-metallic substance or sometimes a low-melting-point alloy. A suitable

substance (silicon tooling) used for the production of the mould and plastics, in

particular, have the advantage of producing moulds that have a long service life - i.e.,

can be reused a large number of times. Moulds may comprise one, two or three parts,

depending on the complexity and shape of the model.

For a non-conductive mould the surface of the mould is coated with an electrically

conductive material to allow the electrical circuit to flow. The preferred method is a

fine film of silver sprayed to the surface, other methods include brushed fine graphite

powder or a metallic powder suspended in a thin lacquer.

Using direct current and the principle of electrolysis electro-deposition of metallic

coatings are done in an acid or alkaline salt solution containing the metal to be

deposited. The mould becomes the cathode when connected to the negative pole and

the anode or positive pole is usually made from the metal being deposited. The anode

is gradually consumed during the process. Various auxiliary techniques are applied -

such as the use of internal anodes, masking, etc. - to ensure that a uniform and smooth

metallic coating is formed. By the addition of special substances it is possible to

enhance the smoothness, fineness and lustre of the coating. When a coating of the

desired thickness has been attained, the shell is rinsed, removed from the mould and, if

necessary, given a finishing treatment. Next, the shell may be given backing or filling

of low-melting-point alloy, or some other material, to strengthen it. [20]

8

Figure 2.1 – Electroforming Process

Electroforming is used for a variety of purposes: e.g., making copies of archaeological

or art objects, printing plates, metal discs in the manufacture of phonograph records,

embossing dies, templates, molds for casting, and many object used in mechanical and

electrical engineering. [20]

8) Backfilling the copper shell with aluminium filled epoxy for

extra strength and support

9) Trimming excess materials to finish the copper

electroformed electrode

1) Producing a master pattern in a SLA resin

2) Making a Silicon Mould of the master pattern

3) Removing master pattern from the silicon mould

4) Applying a conductive coating to the mould

Conductive coating

7) Separating the copper shell from the mould

6) Copper electroformed shell in the silicon mould

Copper plating

5) Copper electroforming (electroplating) the mould in an electrolytic cell

9

2.3 SPRAY DEPOSITION

Spray deposition is a process also known as spray-metal deposition, plasma spray

deposition, plasma spraying and plasma deposition. Research in recent years has

shown advances in the use of spray metal and the resulting properties [4-9].

Spray metal deposition involves spraying atomised molten metal on to a pattern to

produce a copy of the surface required as shown in Figure 2.2. The process produces

a shell on the surface of the pattern that is usually removed and back filled to provide

a low cost alternative to producing a solid metal model. The moulds can be made cost

effectively from wood, metal, plastic, ceramic or even leather. These moulds can

become very inexpensive due to the fact that they can be used more than once.

Figure 2.2 – Spray Metal Deposition Process

Pattern

Arc Gun Air Flow

Wire material supply

Arc Region

Deposit

Spray

10

The benefits of Spray Metal Tooling are that it cost 75% less and moulds can be made

in 1/5 of the time. There are various applications in which spray metal tooling is

used:

• Prototype Injection Moulds

• Polyurethane Tooling

• Structural Foam

• Thermoform Tooling

• Blow Moulds

• I.S.P. (instant set polymers)

• Spray Metal Tooling can be used to reduce cost of prototype moulds for;

o Evaluating Injection Moulding Compounds

o Make Custom Trade Show Samples

o Test Physical Characteristics of Moulded Products

o Develop Spray Masks From Moulded parts

o Determine if Shrink Fixtures are Necessary

2.4 EDM

The Electro-Discharge Machine, shown in Figure 2.3, used in the project is the Sodick

Mould-Maker 3 NF40 situated at QMI Solutions in Brisbane.

11

Figure 2.3 – Sodick Mould-Maker 3 NF40

The EDM system consists of a shaped tool (electrode) and the work piece, connected

to a DC power supply and placed in a dielectric fluid. When the potential difference

between the tool and the work piece is sufficiently high, a transient spark discharges

through the fluid and removes a small amount of metal from the surface of the work

piece.

The amount of metal removal rate, surface finish and tool wear are dependent on the

voltage, current and frequency of sparks. Increase in voltage and current results in an

increase in material removal rate and surface roughness.

Due to the machining process occurring without any machining forces, EDM is the

ideal machining process for very fine detailed machining to be done. EDM allows the

steel to be hardened prior to machining to remove the possibility of distortion after

machining.

12

2.5 LITERATURE REVIEW

Research groups have been researching into many areas of Rapid Prototyping and

Tooling. Areas of Rapid Tooling that research has been conducted and is continuing

in include forming tools[21], stereolithography injection mould tools[22, 23], Roto-

tools for casting[24] and polymer infiltration for rapid tools[25]. These areas in rapid

tooling show that there is still a large scope for potential research to improve

traditional and non-traditional tooling. Harris et al. [22, 23] indicates that production

of low volume of parts can be done in much less time and lower costs using the rapid

tooling technologies. Noguchi and Nakagawa [21] have shown that combining RP

processes (SLA and Sintering) provides a useable method of producing metallic rapid

forming tools. Chan et al. [24] provide a proven case for the introduction of rapid

tooling into a traditionally labour intensive and expensive process.

Areas of Rapid Prototyping have been more extensively investigated and researched.

RP covers areas like Laminated Object Manufacture (LOM), Stereolithography

(SLA), and Selective Laser Sintering (SLS). These RP processes are often used as the

initial steps to lead in to Rapid Tooling. Mueller and Kochan [26] have researched

and shown that LOM provides a cheap and effective option as the initial steps for

foundry casting patterns. Extensive use of SLA has been used in the initial steps of

prototyping and manufacture in the areas of injection mould tooling [22, 23, 27], sheet

metal drawing [28], precision forming tools [21], and EDM tooling [3, 10, 11, 14, 15,

18, 19, 29, 30].

“EDM has the advantage of allowing tool steel to be treated to full hardness before

machining, avoiding problems of dimensional variability which are characteristic of

post treatment”[14]. EDM (Electric Discharge Machining) or spark erosion is a non-

traditional machining process used on hardened tool steels when complex and detailed

surfaces are required. In die and mould production, the EDM cycle can account for

25 to 40% of the tool room lead-time [1, 2]. The electrode production represents over

50% of the cost and time of an EDM operation [2]. In today’s manufacturing

environment cost reduction is a main goal, and a great emphasis is placed on the

reduction of time to complete tasks.

13

Decreasing time and improving efficiency of processes is the main focus of many

researchers. Advancements in Rapid Prototyping have allowed for great time saving

in current processes. Rapid Prototyping (RP) and associated techniques like Rapid

Tooling have played a major role in research of cost and time reduction. Rapid

Tooling technologies offer an alternative method of production the promises to

drastically reduce the time involved in design and manufacture of tools [1-3, 10-12,

14-19, 21-25, 29-34]. Within RP, Stereolithography is one of the main methods used

in producing tools. RP is now considered to have a vital role in product development,

cost reduction and time saving [31].

The conventional methods of producing electrodes include stamping, coining,

grinding, extrusion/drawing, turning and milling from materials including copper,

brass, steel and graphite. RP Technology can be used directly or indirectly in the

production of EDM electrodes. Main methods of RP electrode manufacture include

sintering [25, 35-37], electroforming [14, 17-20, 27-29, 38-49], and spray metal

deposition [5, 7, 45]. A facility to sinter metal powder wasn’t available for the

research so electroforming and spray metal deposition was used.

The direct method uses a manufactured model as the electrode or a model that has

been coated by deposition or sheet formed. The direct method has been previously

carried out using the following three approaches: Electrically Conductive Plastic

[32](doesn’t have sufficient electrical conductivity at present); Metal Powder

Impregnated SL Resin Substrate [16, 32] (dismissed due to the inability to cure the

composite resin); Application Of Coatings To Substrates (Various routes from SL

model through metallising and coating to EDM electrode have been identified and

show potential to be viable)[10-12, 15].

The indirect method of electrode manufacture involves the manufacture of a negative

mould in which a shell is produced using material deposition or sheet deformation.

The shell is then backed with a suitable resin or low melt alloy [14]. The following

techniques have been used: Coated Electrodes from Negative Pattern (the negative

pattern is used with electroforming, galvanic plating and spray metal. All have shown

promise except spray metal has poor efficiency due to porosity) [1, 14, 16, 32]; Tartan

14

Tooling and Rotational Copper Casting (Has promising results with electrodes in

copper/tungsten claiming better wear rates than graphite) [33]

Experiments using the direct manufacturing [11, 12, 14, 15, 17] and indirect

manufacturing [16] methods have been attempted to differing degrees of detail.

Arthur et al. [11, 12, 14] mainly researches the electroformed electrodes by optimising

the parameters to get the best MRR, TWR and Ra as possible. Rennie et al. [17]

researched into how the wall thickness of the electroformed shell affects the

machining time.

Leu et al. [15] and Jensen et al. [16] have shown comparisons between non-traditional

electroformed electrodes and traditional machined electrodes. Jensen et al. [16] have

shown a general comparison between electroformed electrodes and machined

electrodes but don’t give much detail into performance of the electrodes. Research by

Leu et al. [15] shows a more details comparison of the different electrodes in terms of

MRR, TWR and Ra but their work is on directly manufactured electrodes. There

appears to be insufficient information in the investigation of the efficiency of indirect

manufactured electrodes (using electroforming and spray metal) compared to

traditional solid electrodes through the manipulation of EDM process parameters.

The lack of information on indirectly manufactured electrodes provided the need to

research further into the non-traditional methods of manufacturing electrodes. There

was also a lack of research into using complex shaped electrodes manufactured in

methods other than the traditional machining.

The previous work carried out that lead into this proposed project includes work done

by Ang in 1998 [30], Hung in 1999 [29] and Yarlagadda, et al. in 1999 [19]. Ang

applied Rapid Tooling techniques to produce electroformed electrodes that were used

in experiments to replace traditional machining with non-traditional machining EDM.

Experimental results showed the potential of the electroformed electrodes in

comparison to solid copper electrodes, but inadequate flushing lead to the failure of

the electrodes.

15

Hung [29] performed experiments based on the work of Ang [30] and concluded that

the electroformed electrodes performance was based on the shell thickness. A shell

thickness less than 2mm couldn’t withstand long process times of EDM. Yarlagadda

et al. [18, 19] continued research into the electroformed copper electrodes. The focus

was on using stereolithography rapid prototyping to produce the master patterns and

vacuum casting to produce a negative pattern. The negative pattern was used in the

electroforming process to produce the copper shells. The electroformed copper shells

were backed with aluminium epoxy. Their experiments proved the potential for

applications of electroformed electrodes to EDM. Those experiments led to this

proposed research.

16

3.0 EXPERIMENTAL DESIGN

The experiments in this research are based on a similar procedure to Leu et al. - “A

Feasibility Study of EDM Tooling Using Metalized Stereolithography Models” [15].

The procedure allows an indication of the difference in the performance of different

manufacturing methods. Leu et al. [15] provided a comparison between

electroformed copper electrodes and traditional solid electrodes by running

experiments at three different machine settings for a set time of ten minutes. There

were a total of eight experiments per electrode type at each machine setting.

EDM performance is dictated by the machine parameters and the optimisation of

those parameters has been the basis of research by the majority of research groups in

the field of EDM. Many researches have used methods such as neural networks [50-

54] and Taguchi method [55-57] to optimise performance characteristics and machine

parameters.

Due to time and budget restrictions the number of experiments determined the type of

analysis that could be done. The Taguchi method and neural network experiments

require a large number of experiments to prove the methods and the budget didn’t

allow that size research. Leu et al. [15] completed eight experiments per machine

setting for each electrode type and to get results that are comparable, within the

budget, only two experiments for each machine setting and electrode type were

conducted.

A comparison of the three electrodes (solid copper, electroformed copper and spray

metal copper) will be made using the same machining conditions and measuring the

performance attributes. The performance attributes measured include material

removal rate (MRR), tool wear ratio (TWR) and surface roughness (Ra).

The electrodes will be tested under three machining conditions and measured to

compare the performance attributes. The machining conditions include a roughing

cut, semi-roughing cut and a finishing cut. Using the same machine parameters for all

three electrodes will allow a good comparison to be made.

17

Using additional test experiments it was determined that using standard preset

machine settings for the three different cuts would be the best way to get comparable

results from the different electrodes at the three different cut settings. The codes

chosen for the machine settings are - C110 – Finishing,

C140 – Semi-roughing,

C170 – Roughing

The machine settings for cutting steel using copper electrodes range from C100 to

C190 when aiming for minimal wear to the electrodes. C110 setting was chosen for a

finishing cut because C100 was extremely fine and the machining time was too high

for the timeframe of these experiments. C170 setting was used because the C180 and

C190 settings were too aggressive for the electroformed electrodes and the C170

setting allowed the test electroformed electrodes to actually machine the test pieces.

The C140 setting was chosen on the fact that it evenly divided the other two settings.

The settings for the three different experiments involve the following parameter

settings –

Table 3.1 – Machine Settings or Finishing, Semi-Roughing and Roughing Cuts

Machine Setting

Discharge Pulse Duration

ON

Quiescent Pulse Duration

OFF

Quiescent Time MA

Peak Current

IP Servo Voltage

SV Polarity

PL C110 012 012 01 002.0 03 +

C140 016 016 01 005.0 05 +

C170 019 019 01 010.0 05 +

The values given are not actual values. They are machine setting numbers for the

scale on the machine. The actual values for the machine settings are as follows:

Table 3.2 – Actual Settings or Finishing, Semi-Roughing and Roughing Cuts

Machine Setting

Discharge

Pulse Duration

ON

Quiescent

Pulse Duration

OFF

Quiescent

Time

MA Peak Current

IP Servo Voltage

SV Polarity

PL C110 80μsec 20μsec X2 2A 35V +

C140 180μsec 20μsec X2 5A 60V +

C170 350μsec 30μsec X2 10A 60V +

18

To restrict the experimental machining time the cut depth will be reduced according to

the cut type. The roughing cut will make a cut of approximately 1mm, the semi-

roughing cut will be 1mm and the finishing cut will be 0.5mm. The machining time is

measured on the EDM computer control unit and it measures to an accuracy of

seconds.

The electrodes and work-pieces will be measured before and after to determine the

MRR, TWR and Ra. The MRR can be measured using one of the following

mathematical equations –

( ) ( ) ( )( )min

min/2

3

CutofTimemmCutofDepthmmAreaElectrodemmMRR ×

= (1a)

( ) ( )( )min

min/CutofTime

gMassElectrodegMRR = (1b)

MRR can be measured by the change in weight or change in volume of the electrode

and the work-piece. Determining MMR was measured in grams per minute as it was

more accurate to measure change in mass than change in volume with the equipment

that was available at the time of the experiments.

The mass of the electrodes and work pieces was measured on standard electronic

scales which measures masses from 0 to 100g to an accuracy of 0.001g increments,

masses from 100 to 500g to 0.01g increments and above 500g to 0.1g increments.

The TWR is measured by –

( ) ( )( ) 100% 3

3

×ΔΔ

=mmVolumemmVolumeTWR workpiece

Electrode

(2)

The measurements can be made by weight and also the use of a coordinate measuring

machine (CMM). CMM was chosen because of the accuracy attainable and also the

availability of the machine itself. The CMM has the accuracy to measure down to

19

0.001mm in horizontal axis and vertical axis. The CMM is used to measure the

vertical height and change of height at preset coordinates in the horizontal plane (x

axis and y axis).

Using the CMM, a grid is used to measure preset points before and after experiments.

The difference is used to determine the amount of wear or material removed from

different sections and features of the electrodes and test pieces.

The Ra is measured using a machine such as a Taylor Hobson Surtronic instrument.

Several measurements are made on each electrode and test piece to give and average

roughness of the whole machined surfaces. The surface roughness is measured to the

very fine increments of 0.01μm. The measuring probe scans a 4mm section of the

surface and then determines the average surface roughness (Ra).

Measurements for the experiments were made on equipment available but the

measurements such as the masses, volumes and heights could have been measured to

greater accuracy with more advanced machines. The volume is one method that was

unable to be used but if a three dimensional scanner was available it would have been

possible to measure the change of volume.

20

4.0 EXPERIMENTAL PROCEDURE

The experimental results compare the performance of the different electrode

manufacturing methods at the three different machine settings. The aim is to compare

the electrode performance at different workloads on the electrode from roughing cuts,

semi-roughing and finishing cuts. The three settings cut at different speeds so the

depth of cut for the finishing cut was reduced. This was to prevent the machining time

from climbing too high.

The selection of electrode shapes (Figure 4.1) was to help compare different areas of

tool manufacture and performance. Tool shapes were developed from previous

research carried out by Subramanian [3], who showed that trying to test the different

geometries in one tool was not as helpful so the shapes were developed separately.

The three shapes developed highlighted the tools machining performance and the

ability to cope with a broad range of tool features and shapes. The new tool shapes

include smooth curved surfaces, sharp corners, low draft angles and complex deep

holes and this differs from previous work carried out by Leu et al. [15] because their

research was done using very simple shaped machining into a flat work piece. The

complex shapes were also used to get an indication of the limitations of the

Electroforming and Spray Metal processes to produce the various shapes and then

their suitability to be used in the EDM process.

The electrodes were all set up in the same conditions and the similar shapes made the

same cuts at the same settings. The depth of cut is measured from the top surface of

the work piece and the experiments begin with the depth of the hole in the near net

casting. The first four experiments are 1mm cut added to the previous measurement

and the final two experiments are 0.5mm extra.

21

Figure 4.1 – SLA Electrode Master Patterns

The electrodes and work pieces were measured before and after each experiment to

determine the MMR, TWR and Ra.

Using the CMM and a 2mm grid as shown in Figure 4.2, heights were measured to

determine the material removed in the machining process.

Figure 4.2 – Electrode grid measurements

2mm

22

The coordinates measured were tabulated as in Table 4.1 and graphed as shown in

Figures 4.3 (before experiment) and Figure 4.4 (after experiment) to give a visual

representation of the measurements.

Table 4.1 – CMM Coordinate measurements of the electrode height

Y x

16.000 14.000 12.000 10.000 8.000 6.000 4.000 2.000 0.000 -2.000 -4.000 -6.000 -8.000 -10.000 -12.000

16.000 0.025 0.017 0.015 0.010 0.007 0.004 0.000 -0.004 -0.002 -0.003 -0.006 -0.007 -0.005 -0.008

14.000 0.020 0.019 0.011 0.010 0.006 0.045 -0.027 0.018 0.018 0.028 -0.010 0.019 -0.007 -0.011 -0.009

12.000 0.024 0.018 0.015 0.018 0.025 0.057 0.016 -0.003 0.002 0.008 -0.025 0.000 -0.010 -0.008 -0.010

10.000 0.025 0.019 0.019 0.074 0.021 0.030 -0.056 -0.046 -0.109 -0.035 -0.089 -0.001 -0.010 0.024 -0.011

8.000 0.021 0.017 0.034 0.065 0.001 -0.020 -0.102 -0.096 -0.134 -0.090 -0.127 -0.017 -0.012 0.013 0.099

6.000 0.023 0.052 0.043 0.009 -0.039 -0.080 -0.086 -0.062 0.000 0.018 -0.075 -0.061 -0.015 0.007 -0.003

4.000 0.022 0.049 0.057 -0.007 -0.007 -0.029 0.060 0.143 0.152 0.166 0.154 0.024 0.016 0.031 0.017

2.000 0.022 0.045 0.000 0.007 0.001 0.070 0.143 0.159 0.129 0.155 0.140 0.122 0.011 0.052 0.003

0.000 0.021 0.037 0.009 0.002 0.015 0.070 0.156 0.137 0.136 0.153 0.153 0.155 0.025 0.024 0.003

-2.000 0.021 0.026 0.016 -0.030 -0.044 0.027 0.186 0.146 0.138 0.138 0.151 0.141 0.032 0.001 -0.008

-4.000 0.018 0.036 0.003 -0.026 -0.066 -0.044 0.084 0.133 0.160 0.148 0.209 0.102 0.023 -0.018 -0.038

-6.000 0.015 0.023 0.025 -0.030 -0.021 -0.124 -0.055 -0.050 0.073 0.035 0.058 -0.011 -0.036 -0.070 -0.036

-8.000 0.012 0.004 0.043 0.000 -0.025 -0.083 -0.089 -0.130 -0.122 -0.115 -0.076 -0.077 -0.045 -0.064 -0.051

-10.000 0.008 0.004 0.013 0.032 -0.033 -0.047 -0.071 -0.060 -0.069 -0.014 -0.047 -0.048 -0.065 -0.023

-12.000 0.007 0.000 -0.002 -0.006 0.051 0.014 0.057 -0.041 -0.001 -0.035 0.023 -0.061 -0.047 -0.029 -0.024

-14.000 0.006 0.000 -0.005 -0.011 -0.016 -0.097 0.032 -0.069 0.015 -0.045 0.034 -0.116 -0.019 -0.023 -0.020

16.0

00

12.0

00

8.00

0

4.00

0

0.00

0

-4.0

00

-8.0

00

-12.

000

-16.

000

16.000

10.000

4.000

-2.000

-8.000-14.000

-5.000

0.000

5.000

10.000

15.000

20.000

25.000

30.000

Height (mm)

Length (mm)

Width (mm)

Electroformed Electrode EC1a

Figure 4.3 - Electrode Measurements before Experiment

23

16.0

00

12.0

00

8.00

0

4.00

0

0.00

0

-4.0

00

-8.0

00

-12.

000

-16.

000

16.000

10.000

4.000

-2.000

-8.000-14.000

-5.000

0.000

5.000

10.000

15.000

20.000

25.000

30.000

Height (mm)

Length (mm)

Width (mm)

Electroformed Electrode EC1b

Figure 4.4 - Electrode Measurements after Experiment

The used measurements are subtracted from the unused measurements to give the

result shown in Figure 4.5. The graph gives an indication of the amount of material

removed and the areas of most material removed. These graphs are used to give a

visual comparison between the wear experienced by the different manufacturing

methods of the electrodes.

24

16.0

00

12.0

00

8.00

0

4.00

0

0.00

0

-4.0

00

-8.0

00

-12.

000

-16.

000

16.000

10.000

4.000

-2.000

-8.000-14.000

-0.150

-0.100

-0.050

0.000

0.050

0.100

0.150

0.200

0.250

Height (mm)

Length (mm)

Width (mm)

Electrode Wear EC1a-b

Figure 4.5 - Material removed from the electrode during the experiment.

The results in Table 4.2 show the masses before and after the experiments and the

calculations performed to determine the MRR using equation 1b (p18) and TWR

using equation 2 (p18). When calculating the MRR and TWR the results needed to

indicate if there was or wasn’t any significant difference throughout the corresponding

experiments.

Table 4.2 – Mass measurements and calculations taken from experiments

machine

time (min) MRR

(g/min) TWR (%)

Electroformed Base A B A-B A-B 1 63.616 63.423 0.193 46.80 0.004 1.804 2 80.044 79.696 0.348 49.53 0.007 2.122 3 71.027 70.851 0.176 89.83 0.002 1.375 4 58.865 58.359 0.506 211.33 0.002 2.410 5 59.02 58.185 0.835 990.03 0.001 23.857 6 75.63 74.55 1.08 1947.75 0.001 12.000

The Taylor Hobson Surtronic instrument was used to measure the Ra of the electrodes

and the work pieces. The measurements were taken on all sides and accessible

surfaces of the used electrodes and test pieces. Results were tabulated as shown in

25

Table 4.3. Because the results were only compared using the Ra value the Rq, Rt and

Rsk values were not used.

Table 4.3 – Measurements of Ra from the Taylor Hobson Surtronic

Experiment 1 Ra mm Rq mm Rt mm Rsk FC2b 1 6.82 8.62 47 0.06 2 6.27 8.19 45.6 0.22 3 6.68 8.12 41.4 0.37 4 7.89 10.41 58.4 0.57 Average 27.66

26

5.0 EXPERIMENTAL RESULTS

A total of six experiments were carried out. Due to manufacturing costs two sets of

three solid copper electrodes, six sets of three electroformed electrodes and two sets

of three spray metal electrodes were produced. As explained later in this chapter the

spray metal electrodes didn’t work as expected. Due to the porosity and uneven

thickness in the spray metal electrode shells the backing material penetrated and made

the electrodes unusable. Therefore the performance of the spray metal electrodes

failed before making it to the EDM stage.

5.1 EXPERIMENT 1

A roughing cut was used in the first set of experiments with the machine set on a

standard machine setting of C170. This produced high MRR and Ra with low

machining time and TWR.

The machine and actual settings were as follows:

Nominal Actual

Machine Setting: C170 C170

Discharge Pulse Duration (ON): 019 350μsec

Quiescent Pulse Duration (OFF): 019 30μsec

Quiescent Time (MA): 01 X2

Peak Current (IP): 010.0 10A

Servo Voltage (SV): 05 60V

Polarity (PL): + +

The following is the depth of cut for the first set of experiments:

Cone Electrode – 28mm

Triangle Electrode – 26mm

Base Electrode – 19mm

27

5.1.1 Solid Electrodes compared to Electroformed Electrodes

The performance of the electrodes can be compared in several ways. Tool wear shows

the durability of the electrode itself. Results of experiment 1 show that the tool wear

is greater in the electroformed electrodes. The following Figures 5.1(a) and 5.1(b)

have been given the same measurement scales to give a true indication of the

comparison in wear. Figure 5.1(a) shows that solid electrode has very little wear and

any wear that has occurred is less than 0.05mm. The electroformed electrode hasn’t

performed as well as the solid electrode and this is emphasised in Figure 5.1(b) by the

wear being greater than 1mm on the sharp corners and over 0.1mm around the edges.

Figures 5.1(a) and 5.1(b) are shown as an example of the difference in wear and in the

following experiments the figures will be supplied in Appendix A.

One of the problems encountered when using the electroformed electrodes was the

ability to damage the electrode when beginning the experiment. The expanded view in

Figure 5.2 shows the damage that can happen. The damage was cause by a lack of

conduction through the electrode holder and the electrode. During the setup the

electrode came in contact with the work piece and did not produce a circuit to register

in the z axis.

Figure 5.2 also shows the wear that occurs on the sharp corners of the electrode. The

green line gives an estimate on the shape of the original electrode. There is very little

taper on the walls of the base electrode and that resulted in very little work being

performed by the vertical walls of the electrode.

28

-24.

000

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

24.0

00

-20.000

-12.000

-4.000

4.00012.000

20.000

-0.200

0.000

0.200

0.400

0.600

0.800

1.000

1.200

1.400

Height (mm)

Length (mm)

Width (mm)

Electrode Wear SB2 a-b

Figure 5.1(a) – Base Electrode Wear Experiment 1 - Solid Electrode

-24.

000

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

24.0

00

-20.000

-12.000

-4.000

4.00012.000

20.000

-0.200

0.000

0.200

0.400

0.600

0.800

1.000

1.200

1.400

Height (mm)

Length (mm)

Width (mm)

Electrode Wear EB1

Figure 5.1(b) – Base Electrode Wear Experiment 1 - Electroformed Electrode

29

Figure 5.2 – Damage and excessive wear of Electroformed Base Electrode (EB1)

The cone electrodes show similar characteristics as the base electrodes in that the solid

electrode (Figure A.1) has less than 0.1mm wear and the electroformed electrode

(Figure A.2) shows greater wear of over 0.1mm on the higher sections. The negative

wear on the electroformed electrodes was caused by the deformation of the electrode.

Heat from the EDM process builds up in the copper and is partially insulated by the

back filled material therefore expanding the copper. Increased localised wear on the

point of the electrode is also caused by the extra work performed by the tip. The work

piece is a near net casting and the cavity has more material to remove at the base of the

cavity until the hole is identical to the electrode shape. The following experiments

experienced a more even work rate.

The CMM results for the solid cone electrode shows a negative wear in a small area

near the front left of Figure A.1. The negative wear is the result of a carbon build up

from an inclusion in the work piece casting. Figure 5.3 shows the inclusion that

appeared after the first experiment and the black carbon build up on the electrode.

The inclusion didn’t appear to affect the MRR.

30

(a) Work piece (b) Electrode

Figure 5.3 – Casting Inclusion and Electrode Wear

Triangle electrodes gave a very good indication of excessive wear when the electrode

is needed to machine larger amounts of material. As shown in Figure A.3 the solid

electrode has lower wear than the electroformed electrode. Figure A.3 has two points

of very high negative wear. The negative wear is from the CMM trying to measure an

edge of the electrode and not hitting exactly the same points when remeasuring.

Figure A.4 shows negative wear on the large angled surfaces which is caused by

expansion of the copper around the back filled core.

The higher wear along two sides of the electrodes was produced by increased work

rate. The cavity of the near net castings is slightly smaller than the electrodes and any

vertical surfaces will be machined more than the surfaces that are more horizontal.

Figure 5.4 shows the difference in size of the near net casting and the electrodes.

31

Figure 5.4 – Machining of triangle work piece in experiment 1

The solid triangle electrode performed better than the electroformed electrode in terms

of the shape of the machined cut, because the electroformed electrode failed during the

experiment. The sharp corners of the electrode wore through to expose the back filled

core and therefore stopped machining in that small are. Figure 5.5 shows the results of

the failure.

(a) Failed Electroformed Electrode (b) Experiment 1 Work Piece

Figure 5.5 – Failed Electroformed Electrode and Experiment 1 Work Piece

5.1.2 Work pieces machined by different electrodes.

Machining the work pieces in Experiment 1 involved a roughing cut to remove

material fast to be left with the rough shape required. Additional cuts are made to get

to the final shape, depth and finish required. Experiment 1 was set up to make a 1mm

Material Removed

Work Piece

Electrode

32

cut at measured from the base of the existing near net cast hole. Figure A.5 shows that

the original base hole wasn’t uniform in depth and the electrodes were used to

machine holes as even as possible to continue with the experiments. Both electrodes

reached the flange before finishing the cut.

Machining with the solid base electrode (Figure A.5) gave a reasonably even cut to a

depth of 0.5mm around the flange and a little more inside the hole. A few spikes of

over 2mm indicated that some machining was done on the vertical surfaces. An

uneven result was given by the electroformed electrode. Figure A.6 shows that the

flange removed a very uneven amount of material. The electroformed electrodes

could not be guaranteed to be perfectly flat on the flanges and the larger flat surfaces.

Machining with the cone electrodes provided very similar results for both Solid

(Figure A.7) and Electroformed (Figure A.8) Cone Electrodes. As shown in Figure

A.7 the material removed was up to approximately 4.5mm but the point of origin for

the measurements in the centre of the work piece shows a depth of cut close to 1mm.

The extra depth of machining around the centre is due to the near net casting hole

having a reduced taper angle to the electrodes.

Work pieces used for the triangle electrodes gave very similar results when put under

the CMM. Figure A.9 and Figure A.10 show very similar results for the solid and

electroformed electrodes, apart from the failed corners of the electroformed electrode

(Figure 5.5). Both work pieces show that there has been more material removed along

the vertical walls of the holes. The rest of the machined area shows a reasonably even

1mm depth of cut.

Apart from the CMM measurements, change in mass, machining time, material

removal rate (MRR) and tool wear rate (TWR) were also measured and calculated.

The change in mass (Table 5.1) and the machining time (Table 5.2) were used in

equation 1 to determine the MRR (Table 5.3) and also equation 2 to result in TWR

(Table 5.4). The resulting MRR figures indicate that all electrodes performed evenly

at a roughing cut setting.

33

Table 5.1 – Change in Mass for Experiment 1

Change in Mass Grams

Solid Base Electrode 0.1

Electroformed Base Electrode 0.193

Solid Cone Electrode 0.38

Electroformed Cone Electrode 0.123

Solid Triangle Electrode 0.62

Electroformed Triangle Electrode 0.359

Base Work piece (solid) 7.7

Base Work piece (electroformed) 10.7

Cone Work piece (solid) 19.8

Cone Work piece (electroformed) 18.3

Triangle Work piece (solid) 21.9

Triangle Work piece (electroformed) 18.0

Table 5.2 – Machining Time for Experiment 1

Machining Time Minutes







34

Table 5.3 – Material Removal Rate for Experiment 1

Material Removal Rate Grams/Minute







Experiment 1 was used to make a clearing cut on the work pieces to basically set up

the work pieces for the following experiments. To get a more precise indication of the

performance of the electrodes it is recommended that all of the experiments should be

looked at before making conclusions. Table 5.4 shows TWR for Experiment 1 are

very similar showing very small wear on all electrodes.

Table 5.4 – Tool Wear Rate for Experiment 1

Tool Wear Rate Percentage (%)







The final measurement for each experiment is the surface roughness Ra (Table 5.5).

All work pieces measured high in roughness except the base work piece for the

electroformed experiment. The low Ra is a result from a lack of work done by the

vertical walls of the electrode. When measuring the surface roughness, the probe is

only able to measure surfaces accessible from the top of the work piece and therefore

the surfaces measured are the vertical walls. Figure 5.6 shows how the electrode has

not performed much work with the vertical walls. The silver regions are the parts of

35

the electrode that didn’t do any work whereas the black sections are where a spark was

produced leaving a small burn mark.

Table 5.5 – Average Surface Roughness Ra μm, Experiment 1

Ra Average μm

Cone Work piece (electroformed) FC2b 6.92

Cone Work piece (solid) FC3b 7.04

Triangle Work piece (electroformed) FT1b 6.28

Triangle Work piece (solid) FT2b 6.75

Base Work piece (electroformed) FB2b 3.61

Base Work piece (solid) FB1b 5.63

Figure 5.6 – Electroformed Base Electrode for Experiment 1

5.2 EXPERIMENT 2

Experiment 2 was conducted using the same settings as used in experiment 1 which

meant it was another roughing cut. The machine setting remained at C170 but the

depth of cut was set 1mm deeper.

The following is the depth of cut for the second set of experiments:




36

As in experiment 1 the results gave high MRR and Ra with low machining time and

TWR.


The base electrodes performed very similar to experiment 1 when measured by the

CMM. The solid electrode (Figure A.11) completed the experiment with wear of less

than 0.01mm over the majority of the electrode. Wear of greater than 0.01mm was

measured only in several points on the sharp edges of the electrode. There is

considerably more wear on the electroformed electrode (Figure A.12) compared to the

solid electrode. The wear on the complex shape of the electroformed electrode was

concentrated on the sharp edges and corners and measured over 0.05mm up to

0.35mm which is a similar pattern to experiment 1.

Again the majority of the machining was performed by the horizontal surfaces of the

base electrodes. Figure 5.7 shows the black areas from which sparks were generated

and the silver areas that have not done any machining. As the electrode gets within

the critical distance to the work piece a spark will jump from the electrode to the work

piece removing material from both the electrode and work piece.

Figure 5.7 – Electroformed Base Electrode

Again the wear on the cone electrodes followed the previous experiments in that there

is significantly more wear on the electroformed electrode. Figure A.13 shows that the

majority of wear on the solid electrode is less than 0.05mm compared to Figure A.14

37

showing more than 0.2mm wear on the electroformed electrode. The wear on the solid

electrode is more even than the electroformed electrode. Figure A.14 shows that the

wear is concentrated in the centre of the electrode which is also the highest tip of the

cone electrode.

Although Figure A.14 does not show the damage to the electroformed electrode, there

was a small amount of damage done when setting up for the experiment. A small

indent near the top of the electrode (Figure 5.8) was made in the same way as the

damage on the electroformed base electrode in experiment 1. The problem was

rectified for following experiments with an altered electrode attachment to the EDM.

Figure 5.8 – Electroformed cone electrode – Experiment 2

Electrode wear for the triangle electrodes followed the pattern of the previous

experiments. The solid electrode (Figure A.15) showed the same wear pattern to

experiment 1 and also the problem of the CMM not measuring exactly the same points

as the previous measurements. Apart from the erratic points along the edges of the

graph, the main wear is shown along the centre of the electrode which is the centre

ridge of the electrode.

The electroformed electrode (Figure A.16) showed some wear but there was more

change in measurement due to warping. The CMM measurements showed a lot of

uneven change in the positive and negative. Figure 5.9 shows how uneven the

electrode machined and was worn.

The uneven machining done by the electrode will cause changes to the following

experiments in that the next electrode will be machining an uneven surface.

38

Figure 5.9 – Electroformed triangle electrode – Experiment 2

5.2.2 Work pieces machined by different electrodes

Machining of the base work pieces was much more even over the entire surface.

Figure A.17 and Figure A.18 show that almost the entire surface was machined to a

depth of 1mm. Both electrodes show almost identical machining performance.

Several high points on the graphs are the result of the CMM measuring a point that has

been machined on a vertical surface. The cavity erodes slightly larger and the CMM

probe measures down the inside of the wall of the cavity to give the higher

measurement.

Even machining of approximately 1mm (Figure A.19) was measured across the

machined surface of the work piece machined by the solid electrode. Due to the

damage occurring to the electroformed electrode during setup, the work piece

displayed uneven machining when measured on the CMM (Figure A.20).

Again the solid electrode has machined evenly at 1mm with a small amount of extra

wear down the side of the cavity (Figure A.21). As the electrode machines deeper, the

electrode walls also machine a small amount sideways. The electroformed electrode

machined another 1mm deeper into the work piece however the warping of the

electrode shown previously in Figure A.16 gave uneven machining shown in Figure

A.22.

39

Table 5.6 showed the change in mass of the electrodes and work pieces during

experiment 2. The wear on the electrodes show that the electroformed electrodes

didn’t perform as well as the solid electrodes in that the wear is higher for the

electroformed electrodes in all three electrode shapes. The machining of the work

pieces shows very similar material removal for both solid and electroformed

electrodes. The similarity is true except for the damaged electroformed cone electrode

which had problems during set up.

Machining time shown in Table 5.7 indicates that the time taken to machine the work

pieces is similar for the different electrode types but is very different for the different

shapes of electrodes. The surface area of each electrode has an influence on the

machining time as there is more material removed when there is greater surface area.















40









MRR gives a much more even method of comparing electrode performance. The

MRR for experiment 2 is very similar to experiment 1 machining within 0.2 g/min of

each other. The performance is also very comparable for all of the electrode shapes

and types shown in Table 5.8. As the previous images and measurements have shown,

the electroformed cone electrode gives a false indication of performance because of

the damage done on the electrode.









TWR again was comparable to experiment 1 except for the damaged electroformed

cone electrode. All acceptable TWR was under 3% for the first 2 experiments (Table

5.4 and Table 5.9).

41









As expected the surface roughness was comparable across all of the work pieces

(Table 5.10). The second experiment was similar to experiment 1 and Ra was at the

high level for a roughing cut. The following experiments are expected to show a

lower Ra for the semi-roughing and the finishing cuts.


Ra Average μm Cone Work piece (electroformed) FC2c 7.09

Cone Work piece (solid) FC3c 8.46

Triangle Work piece (electroformed) FT1c 5.94

Triangle Work piece (solid) FT2c 7.22

Base Work piece (electroformed) FB2c 6.78

Base Work piece (solid) FB1c 6.68

5.3 EXPERIMENT 3

Experiment 3 was the first of two sets of semi-roughing cut experiments. A standard

machine setting of C140 was set for all experiments. This setting produced lower

MRR and Ra with higher machining time but a similar TWR compared to

Experiments 1 and 2. Experiment 3 was another cut of 1mm added to the depth of

experiment 2 which was measured from the top surface of the work piece.

42


Nominal Actual







Polarity (PL): + +

The following is the depth of cut for the third set of experiments:





Performance of both solid and electroformed base electrodes is very similar. The

majority of wear on both electrodes is less than 0.05mm. There are also only a couple

of points on each electrode that have excessive wear and the high measurements as

seen in the first two experiments. The solid electrode (Figure A.23) gave a similar

performance to experiments 1 and 2 but as expected there is an average of slightly

more wear over the machining surface. On closer inspection of the CMM results of

the electroformed base electrode (Figure A.24), there is a significant amount of

negative wear which gives a false impression that the wear is less than experiments 1

and 2. The negative wear is produced from warping of the electrode during EDM

machining. Both electrodes have shown increased wear compared to the previous

experiments.

Again all of the machining was performed by the horizontal surfaces and the vertical

surfaces are almost untouched. Figure 5.10 again shows the black regions the

performed work and the unused silver areas. The sharp edges were the areas of

concentrated wear.

43

Figure 5.10 – Electroformed Base Electrode – Experiment 3

The cone electrodes (Figure A.25 and Figure A.26) have shown a similar trend to the

base electrodes showing increased wear all over the machining surface. Warping has

also effected the electroformed electrodes measurements giving a significant amount

of negative wear shown in Figure A.26. The wear on the solid electrode has increased

to between 0.05mm and 0.1mm compared to the experiments 1 and 2 where the wear

is less than 0.05mm. Increased wear on the electroformed cone electrode is also a

result of the damage and reduced machining that occurred in experiment 2. Due to the

warping of the electroformed electrodes it is hard to determine the magnitude of extra

wear occurring on the electrode compared to previous experiments. The wear pattern

has changed and it is not concentrated in the centre as in experiments 1 and 2. The

wear shows a more even coverage of the electrode machining surface.

Apart form the erratic measurements made along the edges of the electrode the solid

triangle electrode (Figure A.27) showed a very small amount of wear over the

machining surface of the electrode. The majority of the wear is less than 0.05mm and

this is similar to previous experiments except the wear is more evenly spread over the

electrode. Experiments 1 and 2 have shown increased wear along the ridge if the

triangle electrode compared to Experiment 3. Along with the change in pattern the

overall wear on the electrode is slightly higher in Experiment 3, which follows the

trend of the other experiments in Experiment 3.

44

Even though the electroformed cone electrode has again shown the problem of

warping (Figure A.28), it is following the trend of increased overall wear and the

uneven wear is a result of the previous uneven machining in experiment 2.


Machining in experiment 3 showed a similar performance to experiment 2 and the

electrodes performed relatively equal when comparing solid and electroformed.

Figure A.29 shows that the solid electrode machined a very even 1mm of material

from the work piece. The performance of the solid electrode is almost identical as in

experiment 2.

The electroformed electrode didn’t perform as expected and the cut didn’t machine the

full 1mm from the work piece. Figure A.30 shows that the machining depth reached

approximately 0.75mm. The result was affected during the setup of the experiment.

The cutting depth is set by referencing the top of the electrode with the top of the work

piece and setting that plane as zero in the z axis. From the CMM measurements the

electroformed electrode measured a high point. So when the electrode was referenced

against the work piece it was incorrectly zeroed off the highpoint.

The cone work pieces performed similar to previous experiments. The work piece

machined by the solid electrode shows a roughly even machined area (Figure A.31).

The machined area isn’t exactly even because once the EDM reaches the set depth of

cut it will stop machining. And because the setup of the experiment cannot be

guaranteed exactly the same every time the centre of the electrode might not line up

exactly with the centre of the work piece. More accurate experiments could be

performed with greater time allowances and budgets.

Figure A.32 shows the material removed from the work piece by the electroformed

cone electrode. Because of the damaged done to the electrode in the previous

experiment the electrode didn’t remove all of the material it was expected to. The

following experiment removed the additional material and it is shown in the CMM

45

measurements. The uneven machining shows that up to 2.3mm was removed when a

cut of 1mm was set.

The triangle electrodes again show in Figure A.33 that the solid electrode machines a

much more even depth and Figure A.34 shows that the electroformed electrode

machines unevenly because of the warping of the electrodes.

Change in mass (Table 5.11) again basically follows the trend of previous experiments

in that the solid electrodes wear less than the electroformed electrodes. There are a

few slight differences in the trend but the many factors affecting the performance of

the electrode make it very difficult to define the cause. Some of the factors that may

influence the irregularity of the results include electrode warping, flushing, setup and

previous experiments.















Machining time (Table 5.12) shows equal times for machining of the different electrode

types for the different electrode shapes. The only major difference is the electroformed

cone electrode. The electroformed electrode removed 9g of material in 77.40 minutes

46

where the solid electrode only removed 4.2g in 46.58 minutes. A better comparison is

given when comparing the MRR in Table 5.13.









As expected the MRR is reduced compared to the first two experiments. The C140

setting has lowered the MRR to below 0.160 grams per minute (Table 5.13) compared

to the C170 setting where the MRR was above 0.330 grams per minute on average.









The Tool Wear Rate (Table 5.14) has shown comparable figures to Experiment 1 and

2. There is no significant change between the roughing and semi-roughing cuts.

47









Surface Roughness (Ra) is a measurement that was expected to reduce when changing

the machine setting from C170 to C140. Table 5.15 shows that the Ra for the work

pieces has reduced by approximately 2 μm which is roughly 25% on average.


Ra Average μm Cone Work piece (electroformed) FC2d 5.63

Cone Work piece (solid) FC3d 5.27

Triangle Work piece (electroformed) FT1d 6.11

Triangle Work piece (solid) FT2d 6.03

Base Work piece (electroformed) FB2d 4.34

Base Work piece (solid) FB1d 4.41

5.4 EXPERIMENT 4

Experiment 4 was conducted under the same semi-roughing machine setting as

Experiment 3 of C140 and the depth of cut was again 1mm deeper. Again the results

in all areas were very similar to the results of Experiment 3.

The following is the depth of cut for the forth set of experiments:




48


Again the solid and electroformed electrodes provided comparable performance over

the range of shapes. The solid base electrode (Figure A.35) shows very similar results

to the electroformed base electrode (Figure A.36) and to previous experiments except

the wear on the electrodes has increased on average over the whole electrode. Both

electrodes have shown very consistent results in terms of wear which is less than

0.1mm over the machining surfaces which are similar to Experiment 3. The solid

electrodes still perform marginally better than the electroformed electrodes but both

still show more wear on the sharp edges and corners.

The cone electrodes (Figure A.37 and Figure A.38) are also showing very similar

CMM results to Experiment 3 except the wear is becoming more even across the

machining surfaces and not localised in the centre on the tip of the electrode. The

wear is still approximately in the vicinity of 0.05mm compared to less than 0.05mm on

average for Experiments 1 and 2.

The solid triangle electrode (Figure A.39) has shown very small wear on the

machining surfaces which is less than 0.03mm but it is very similar in magnitude to

Experiment 3. The electroformed triangle electrode continues to shown signs of

warping on the large flat surfaces (Figure A.40).


Apart from the few major spikes the work pieces have been machined very evenly.

The solid electrode (Figure A.42) has machined almost exactly 1mm over the surface

of the work piece. Experiment 3 results influenced the performance of the

electroformed electrode in Experiment 4. The lack of machining was made up in this

experiment as shown in Figure A.42 by the CMM measuring over 1mm for most of

the work piece surface.

49

Again the Cone work pieces have shown relatively even machining over the work

pieces but Experiment 4 was influenced by the results of previous experiments. The

solid electrode removed an average of 1.2mm (Figure A.43) because Experiment 3

only removed 0.8mm on average. Extra machining was also needed by the

electroformed cone electrode (Figure A.44) due to the warping occurring in previous

experiments and not machining the complete 1mm.

The work pieces for the triangle electrodes show the relatively even machining for the

solid electrodes (Figure A.45) the erratic performance of the electroformed electrode

(Figure A.46) from the electrode warping.

The change in mass shown in Table 5.16 shows that Experiment 4 has followed the

trends of the previous experiments in that there is more wear occurring on the

electroformed electrodes. The wear occurring on the solid base electrode was

measured at 0.0 and that result is due to the accuracy of the scales that were available.

The zero measurement also affects the TWR results in subsequent calculations.

Machining time for Experiment 4 (Table 5.17) has increased with comparison to

Experiment 3. The reason for the increase in machining time is because more material has

been removed. The machining area has increased to include the flange area as the

electrode is cutting deeper than the height of the shape of the electrode. The increased

machining time is better compared in the MRR.

The MRR is very similar to Experiment 3 and the electrodes have all performed to a

similar rate between 0.1 to 0.15 grams per minute (Table 5.18).

The wear is slightly more on the electroformed electrodes and also overall measurably

more than the first two experiments. Because the TWR is measured on electrode wear

divided by work piece wear, the resulting TWR (Table 5.19) is similar to the previous

experiments.

50
























Material Removal Rate Grams/MinuteBase Work piece (solid) 0.143






51









The surface roughness (Table 5.20) measured, as expected, almost equal to

Experiment 3 and also shows that the finish is smoother than the first two experiments.


Ra Average μm Cone Work piece (electroformed) FC2e 5.12

Cone Work piece (solid) FC3e 5.54

Triangle Work piece (electroformed) FT1e 6.04

Triangle Work piece (solid) FT2e 5.61

Base Work piece (electroformed) FB2e 5.59

Base Work piece (solid) FB1e 5.53

5.5 EXPERIMENT 5

Experiment 5 is the first of two finishing cuts at a machine setting of C110. The

finishing cut produced a very low MRR and lower Ra. The machining time increased

dramatically and the TWR followed the trend and increased.

52


Nominal Actual







Polarity (PL): + +

The following is the depth of cut for the fifth set of experiments:

Cone Electrode – 31.5mm

Triangle Electrode – 29.5mm

Base Electrode – 22.5mm

Experiment 5 saw the introduction of the second new set of solid electrodes. Due to

budget constraints the number of electrodes produced was reduced and therefore the

same electrodes were used several times.


The introduction of the new solid electrodes reduced the tool wear. CMM

measurements in Figure A.47 show that the wear on the solid electrode measured less

than 0.005mm apart from several points on the sharp edges that measure

approximately 0.01mm. The new electrode performed much better than expected

because it doesn’t follow the trend of more wear as the cutting becomes finer. The

electroformed base electrode followed all of the trends with increased overall wear and

this was shown in Figure A.48. The CMM has measured the wear over the majority of

the electrode at approximately 0.05mm.

The cone electrodes also showed the result of the introduction of the new solid

electrodes. The solid cone electrode resulted in CMM measurements (Figure A.49) of

less than 0.04mm. Wear on the electrode was very small and didn’t register any

53

change in mass to two decimal places. The electroformed electrode showed

significantly more wear (Figure A.50) and it continued the trend of greater wear for

finer cuts.

The triangle electrodes have followed the same trends as previous electrodes in

experiment 5. The new solid electrode (Figure A.51) has shown very little wear over

the electrodes machining surface and this is also shown by the change in mass (Table

5.21). The electroformed electrode showed much more wear than the solid electrode

as well as previous experiments using electroformed triangle electrodes. The CMM

measurements (Figure A.52) also show that some warping has also occurred during

the experiment.


Machining with the new solid base electrode produces a cavity that didn’t actually

reach the 0.5mm depth of cut that was set. The new electrode used for experiment 5

connects to the EDM tool holder slightly different to the first solid electrode and

therefore not machining on exactly the same plane. The CMM measurements in

Figure A.53 show that the electrode machined at a very slight angle and a depth of

approximately 0.45mm.

Previous experiments have affected the depth of cut by the electroformed base

electrode. Figure A.54 shows that the depth of cut reached the set 0.5mm but the

depth was uneven across the machined surface. The electrode was also slightly bowed

across the flange of the electrode which prevented the electrode from machining

evenly. Figure 5.11 shows the electroformed electrode and that the front of the

electrode is untouched and that is shown in the CMM measurements.

The machining of the solid cone electrode reached the depth of 0.5mm but because it

is a new electrode, the setup is slightly different and therefore the electrode performs

slightly different. The erratic performance of the electroformed electrode is shown in

Figure 5.12 by the silver sections of the electrode that haven’t been involved in any

machining. The CMM (Figure A.55) has measured the machining to be slightly off-

54

centre and therefore machining a small amount more from the cavity. The

electroformed electrode has performed very erratically (Figure A.56) and this is a

result of previous experiments.


The triangle work pieces have followed the expected trends. The solid electrode has

machined fairly evenly over the surface (Figure A.57) which was expected. The

machining wasn’t completely down the set 0.5mm cut but that can be explained by the

spark gap reducing from the previous experiment and the wear on the previous

electrode. The sharp edges and the centre ridge of the electrode performed

approximately 0.5mm because the first electrode was slightly worn from previous

experiments. Figure A.58 continues to show how the triangle electroformed electrode

machines erratically due to the previous experiments and the warping of the electrode

shells.

Figure 5.13 shows how the electrode used in experiment 4 has made a cut to a depth of

29mm but due to the wear on the tip of the electrode the depth of cut is uneven

compared to the cut made in Experiment 5. Experiment 5 machined to a depth of

29.5mm but the tip of the electrode performed more work as a result of the previous

electrode.

55

Figure 5.12 – Electroformed Cone Electrode – Experiment 5

The depth of cut is measured from the tip of the electrode to the top surface of the

electrode. As the first electrode wore more on the tip than the flat surfaces therefore

making the larger flat surfaces do more machining.

Figure 5.13 – Measurements of the different performances of Experiment 4 and

Experiment 5

Experiment 5 followed the trend of previous experiments in that more wear occurred

on the electroformed electrodes. The introduction of new solid electrodes has

produced minimal wear on the solid electrodes and was unmeasurable in terms of

mass on the cone and triangle electrodes (Table 5.21). The work pieces had similar

amounts of material removed for each electrode shape.

0.5mm

0.45mm

Experiment 4 – 29mm – Worn Experiment 5 – 29.5mm – New Work

Piece Not to scale

Cut Direction

56















The machining time for Experiment 5 has increased dramatically. An increase in time

was expected as the finishing cut has less current and voltage running through the

electrode and therefore the spark produced is smaller and removes less material per

spark. Table 5.22 shows the measured machining times and the solid electrodes made

the set cuts in considerably less time than the electroformed electrodes but Experiment

5 has increased from an average of 108.31min (Experiment 4) to 563.63min.









57

The MRR (Table 5.23) shows that the solid electrodes perform much better than the

electroformed electrodes. The MRR has dropped significantly from Experiments 3

and 4.









The use of new electrodes has reduced the TWR in Experiment 5 (Table 5.24) for the

solid electrodes but the TWR for the electroformed electrodes has increased

significantly.









The surface roughness of the work pieces in experiment 5 (Table 5.25) dropped from

an average of approximately 5.4μm in experiments 3 and 4 to 3.8μm. The drop in

surface roughness was expected with the machine setting of C110.

58


Ra Average μm

Cone Work piece (electroformed) FC2f 3.50

Cone Work piece (solid) FC3f 2.61

Triangle Work piece (electroformed) FT1f 5.15

Triangle Work piece (solid) FT2f 3.96

Base Work piece (electroformed) FB2f 3.43

Base Work piece (solid) FB1f 4.34

5.6 EXPERIMENT 6

Experiment 6 was conducted under the same finishing machine setting as Experiment

5 of C110 and the depth of cut was again 0.5mm deeper. Again the results in all areas

were very similar to the results of Experiment 5.

The following is the depth of cut for the sixth set of experiments:





Experiment 6 gave very similar results in the performance of the solid base electrode

(Figure A.59) to Experiment 5. The majority of the wear measured less than 0.005mm

and a few sharp points of the electrode measured higher. The electroformed electrode

showed similar performance to Experiment 5 except for the delamination of the

electrode which is shown by measurements of over -2mm and in Figure A.60.

The delamination (Figure 5.14) occurred during the experiment and was only visible

on completion of the experiment. The delamination was caused by inconsistent build

up during the electroforming process and therefore the process depositing a separate

layer into the mould.

59


The cone electrodes showed slightly more wear than Experiment 5 but the majority of

wear was less than 0.1mm and it was fairly even over the whole electrode for both the

solid electrode and the electroformed electrode (Figure A.61 and Figure A.62).

The triangle electrodes again followed the same trends as the previous experiments.

The solid electrode (Figure A.63) measured minimal wear on the CMM and the

electroformed electrode (Figure A.64) again showed some warping occurring during

the machining process.


The machining done by the solid base electrode shows almost exactly what was

expected. The graph in Figure A.65 shows that the CMM has measured very close to

0.5mm over the entire machined surface. The electroformed electrodes performance

was affected by previous experiments but the CMM measured very close to 0.5mm

over the surface. Figure A.66 shows a large spike in the CMM measurements across

60

the back of the work piece. This spike was caused by the delamination of the

electrode as shown in Figure 5.14 and the machining done by the copper that peeled

away.

Again the solid cone electrode has performed as expected measuring very close to 0.5mm

on the machined surface (Figure A.67). Figure A.68 is the result of the warping in the

previous experiment and the electrode has had to machine the material not machined in

Experiment 5 and also there is little work done in the areas where extra machining was

done in Experiment 5.

The solid triangle electrode performed as expected and shows approximately 0.5mm over

the machined surface (Figure A.69). The electroformed electrode also followed the trends

and machined very erratically over the surface (Figure A.70) as it did in previous

experiments.

Experiment 6 follows the previous experiments by showing more wear on the

electroformed electrodes (Table 5.26) even though the same shapes remove similar

amounts of material.















61

Machining time (Table 5.27) for each electrode shape was more similar when comparing

the times to Experiment 5 which had exactly the same machine settings. Due to the

delamination problems encountered with the electroformed electrode the machining time

was dramatically increased.









The MRR for Experiment 6 is almost identical to that of Experiment 5. The solid

electrodes performed better than the electroformed electrodes with a greater MRR

(Table 5.28).









Again the TWR (Table 5.29) for the solid electrodes is very low but has increased

from Experiment 5 and that was because the electrodes are the same ones used in the

previous experiment. The electroformed electrodes TWR have also increased similar

to Experiment 5.

62









The surface roughness has stayed similar to Experiment 5 and the results in Table 5.30

show the Ra average at approximately 4μm.


Ra Average μm Cone Work piece (electroformed) FC2g 3.58

Cone Work piece (solid) FC3g 3.06

Triangle Work piece (electroformed) FT1g 4.50

Triangle Work piece (solid) FT2g 3.53

Base Work piece (electroformed) FB2g 6.29

Base Work piece (solid) FB1g 3.64

5.7 SUMMARY OF ALTERNATIVE ELECTRODE MANUFACTURE AND PERFORMANCE COMPARISON

This section provides a summary of the different electrode manufacturing methods and

gives comparisons in the areas of cost, quality and performance. Even though the

spray metal shells were not successful, the cost comparison was included and due to

the cost of manufacture it would be worth while continuing to develop the technology.

The spray metal shells weren’t successful because the shells had imperfections and the

backfilling broke through the shells. The spray metal shells were produced using

copper wire passed through a Sulzer Metco electric-arc metal spray system. The shell

63

thickness was specified at a minimum of 2mm but the problem areas of the mouldings

were the deep pockets and sharp corners.

Figure 5.15 shows the spray metal shell with the backfilled material protruding. The

possible causes of the failures include the depth of the negative moulds and also the

porosity of the spray metal. Research has shown that the spray metal method cannot

produce a dense enough shell or moulding to be a viable option for industry needs.

Other researchers have managed to achieve densities of 85% to 95% of the density of

solid copper which shows promise for the use of spray metal in rapid tooling in future

research [58].

Figure 5.15 – Defective spray metal shells

5.7.1 Detailed Failure Investigation of Spray Metal Electrodes

The following problems were encountered with the production of spray metal

electrodes:

• A shell thickness of 2mm was requested to give sufficient material to form the

shell. Analysis shows that some sections are up to 3mm thick but other areas

show a serious lack of build up and this has lead to the backing material

breaking through the shell surface and rendering the electrode unusable. It is

very difficult to control where and how thick the material will build up

especially when spraying into deeper cavities. Figure 5.16 shows the thin wall

sections highlighted in the red circles.

64

Figure 5.16 – Sectional Views of Spray Metal Electrodes showing wall thicknesses

• The thickness of the wall sections was directly linked to the angle they faced

the direction of the spray nozzle. Greater material build up was measured on

the surfaces that were closer to perpendicular to the nozzle flow. The surfaces

that were close to parallel received less material and therefore were prone to

failure. If possible the material build up is optimised by getting the spray

direction as close to perpendicular to the nozzle when spraying metal.

• To get the best EDM results the surface of the electrodes need to be as smooth

as possible and the electrodes produced by spray metal deposition were

extremely rough. Figure 5.17 gives a visual comparison between the different

electrode production techniques where the Electroformed electrode is rough

and the machined electrode has a polished surface. Due to the roughness of

the spray metal electrodes the surface roughness (Ra) was not possible to

measure with the same settings and equipment used to measure the

electroformed and solid electrodes. The Ra of the electrode surface was

65

outside the measurable scale of the probe used to measure the surface

roughness and therefore no accurate measurements were attainable.

Figure 5.17 – Visual Surface Roughness comparison between Spray Metal (left) and

Solid Machined Electrodes (right)

• The spray metal process is extremely rough and the actual mould needs to be

tough enough to resist the corrosiveness and temperatures of the spray metal

process. It was found that the molten copper penetrated the surface of the

ceramic moulds that were used and that meant the smooth ceramic surface

could not be reproduced on the electrode shell surface.

• Shell imperfections were present throughout the spray metal shells and these

were also factors that prevented them from being usable. Imperfections such

as inclusions, porosity, and cracking were visible and these problems could be

reduced if there was more refining of the spray metal process. Figure 5.18

shows cracking, white ceramic inclusions and darker areas where the porosity

has allowed some of the backing material to leak through. Adjusting

parameters such as temperature, material flow and mould material may allow

the process to produce usable shells.

66

Figure 5.18 – Surface imperfection in the spray metal shells.

Proposed ways to improve the Spray Metal Electrodes

To allow spray metal to be used for EDM electrode design, some solutions that could

help refine process include:

• Allowing more material to be deposited to meet a minimum wall thickness

across the entire surface and therefore reducing any chances of the backing

material breaking through the shell,

• Placing restrictions on the depth of cavities to be sprayed would reduce the

angles required to get the spray nozzle close to perpendicular when spraying

each surface,

• The moulds need to be made from tougher materials to allow a better

reproduction of the electrode surface. The materials that could be used need to

have a higher resistance to a combination of heat and wear,

• More time, effort and money is needed to refine the spray metal process for

the production of EDM Electrodes.

5.7.2 Cost Comparison

The viability of the electrodes also depends on the cost to produce the electrodes. The

cost comparison is done on the electrodes that were used in this study.

67

The cost of manufacturing the electroformed electrodes includes:

• Master Patterns SLA,

• Silicon negative patterns,

• Electroformed Copper Shells,

• Backfilled with Aluminium filled Urethane,

• Machining mounting surface.

The cost of the manufacture of the solid copper electrodes includes:

• Solid copper Material,

• Machining different electrode shapes,


The cost of manufacture of the spray metal electrodes includes:

• Master Patterns SLA,

• Ceramic negative patterns,

• Spray metal shells,

• Backfilled with Aluminium filled Urethane,


Even though there are less steps in manufacturing the solid electrodes the cost of

manufacture exceeds that of the electroformed and spray-metal electrodes. The cost of

manufacture is only a rough guide as the prices given were for research purposes and

not commercial prices. Table 5.31 shows the cost of manufacture of the electrodes.

Manufacturing times of the electrodes will vary depending on the number of pieces

required. It takes approximately 16 hours to manufacture one set of three electrodes

from solid copper. Manufacturing time for the solid electrodes increase equally with

the number of electrodes as each electrode is manufactured separately. Therefore the

cost of each solid electrode will only vary a little from the original prices given.

The major time consuming part of manufacturing electroformed electrodes is the

electroforming process and it takes approximately 50 hours to manufacture one set of

three electrodes from one mould. Manufacturing time can be dramatically reduced as

68

the number of moulds that can be electroformed is unlimited. The only limitations are

the size of the solution bath and the number of moulds manufactured.

Table 5.31 – Manufacturing Cost Comparison of different Processes

Process Quantity Cost Electroformed Electrodes Master Patterns SLA – 1 shape @ $100 3 shapes $300.00Silicon negative patterns – 3 shapes @ $230 1 set $690.00Electroformed Copper Shells – 3 shapes @ $200 6 sets $600.00Backfilled Aluminium filled Urethane – 1 set @ $92 6 sets $550.00Manual Machining mounting surface – 6 sets @ $100/hour 3 hours $300.00Total Cost – 18 electrodes 6 sets $2440.00Unit Price $135.56Solid Electrodes Solid Copper Material – 1 blank @ $50 6 blanks $300.00Machining electrode shapes – 6 electrodes @ $140/hour 31.5 hours $4,420.00CNC Machining mounting surface – 2 sets @140/hour 1 hour $140.00Total Cost – 6 electrodes 2 sets $4860.00Unit Price $810.00Spray Metal Electrodes Master Patterns SLA – 1 shape @ $100 3 shapes $300.00Ceramic negative patterns – 3 shapes @ $75 6 sets $450.00Spray metal shells – 3 shapes @ $120 6 sets $720.00Backfilled Aluminium filled Urethane – 1 set @ $92 6 sets $550.00Manual Machining mounting surface – 6 sets @ $100/hour 3 hours $300.00Total Cost – 18 electrodes 6 sets $2320.00Unit Price $128.89

Spray metal electrode manufacturing process can be slightly reduced by increasing the

number of cavities in each mould but it is best to make them separately to make sure

an even shell thickness if maintained. The manufacture of the spray metal electrodes

takes approximately 12 hours per set of three electrodes.

Although it is hard to find definite figures on cost comparisons in previous research

there are several research groups that indicate that their research has shown cost saving

potential in these areas of manufacture [19, 22-24, 26, 28, 34, 44, 45, 48, 59]. As

indicated, electroforming and spray-metal can save significantly in cost of

manufacture of electrodes compared to traditional machining. Solid electrodes cost

69

approximately $810 each which is six times more expensive than the electroformed

and spray-metal electrodes at approximately $130.

5.7.3 Performance Comparison of Manufacturing Methods

Figure 5.19 shows that the solid electrodes performed better as the machining became

finer with the finishing cuts. The time taken for each cut at the finer settings (C110)

was much higher and erratic for the electroformed electrodes. All experimental times

are tabulated in Table 5.32.

The machine settings for the three levels of machining as shown in Table 3.2 show

that as the machining goes from C170 (roughing) down to C110 (finishing) the Pulse

ON and OFF drops as does the Peak Current and Servo Voltage. As the parameters

drop the machining time should increase, the MRR should decrease, the TWR should

increase and the Ra should reduce. As the experiments have shown previously in this

chapter, the results followed the expected trends in that the machining time increased,

the MRR decreased and the Ra decreased. The TWR measured as expected for the

electroformed electrodes but the solid electrodes performed against the expected trend.

Table 5.32 – Machining Time Comparison for different electrodes at various settings

Machining Time Table Machine Setting Tool type C170 C170 C140 C140 C110 C110 Electroformed Base 46.80 49.53 89.83 211.33 990.03 1947.75Electroformed Cone 43.37 8.12 77.40 93.97 758.90 651.87Electroformed Triangle 50.83 13.23 46.80 69.28 486.80 598.15Solid Base 19.47 39.40 95.72 119.63 483.45 598.42Solid Cone 85.52 12.53 46.58 107.85 345.78 447.63Solid Triangle 58.02 17.15 49.17 47.78 316.83 524.72

For both electrode types the machine time for the machine setting of C170 (roughing

cut) was very similar and also very consistent over the six experiments conducted. As

the experiments become more refined with the semi-roughing cut (C140) the solid

electrodes start to perform better as the machining time is less than the electroformed

electrodes and the trendlines begin to separate. The solid electrodes also remain more

70

consistent than the electroformed electrodes. The electroformed electrodes begin to

perform a little more erratic.

Machining Time Comparison

0.00

500.00

1000.00

1500.00

2000.00

2500.00

100 110 120 130 140 150 160 170 180

Machine Setting (C value)

Tim

e (m

in)

Electroformed Electrodes Solid Electrodes Electroformed Electrode Trend Solid Electrode Trend

Figure 5.19 – Machining time Comparison

As seen in Figure 5.19 the trend line shows that a greater gap has formed between the

performances of the different electrode types. Again the solid electrodes have shown

better performance than the electroformed electrodes in terms of the average

machining time and the consistency of the performance.

Table 5.33 shows the MRR results tabulated from all of the experiments. The solid

electrodes showed better performance in MRR, as shown graphically in Figure 5.20,

when performing the roughing cuts but all electrodes performed similarly when a

finishing cut was applied. According to Leu et al. [15] the results of the experiments

are similar (Figure 5.21 and Table 5.34) to the results gained in this research in that the

MRR is much higher for the roughing setting and reduces as the machine settings

change towards the finishing cuts. Figure 5.21 shows that the trendlines for the results

of Leu et al. [15] are almost identical and the graph shows the trendlines overlapping.

71

When comparing the MRR results the required accuracy to determine any significant

difference was measured down to an accuracy of 0.001 grams per minute. This

accuracy was only needed when the machining was at the finishing setting of C110

where the machining time increased dramatically. For all other machine settings an

accuracy of 0.01 g/min would have been sufficient to determine any differences.

Table 5.33 – MRR Comparison for different electrodes at various settings

MRR C170 C170 C140 C140 C110 C110 Female Base (Electroformed) 0.229 0.331 0.142 0.099 0.004 0.005

Female Base (Solid) 0.396 0.416 0.160 0.143 0.012 0.013Female Cone (Electroformed) 0.422 0.099 0.116 0.116 0.006 0.007

Female Cone (Solid) 0.232 0.343 0.090 0.131 0.012 0.013Female Triangle (Electroformed) 0.354 0.302 0.143 0.133 0.007 0.008

Female Triangle (Solid) 0.377 0.367 0.142 0.138 0.010 0.011

MRR Comparison

0.000

0.050

0.100

0.150

0.200

0.250

0.300

0.350

0.400

0.450

100 110 120 130 140 150 160 170 180


Gra

ms

per m

in

Work piece (Electroformed) Work piece (Solid) Work Piece (Solid) Trend Work Piece (Electroformed) Trend

Figure 5.20 – MRR Comparison

The average MRR for the solid electrodes shown by the trend line in Figure 5.20 is

better than that of the electroformed electrodes for a roughing cut with a difference of

over 0.05 grams per minute. The performance of the electroformed electrodes has

again shown that it is more erratic than the performance of the solid electrodes. As the

machine settings become the finer the performance of the electrodes converge. The

72

MRR becomes less erratic for both electrode types at the finishing cut machine

settings.

Table 5.34 – MRR Comparison for different electrodes at various settings for research

by Leu, Yang and Yao [15]

R Figure 5.21 – MRR Comparison for research by Leu, Yang and Yao [15]

halla

This figure is not available online. Please consult the hardcopy thesis available from the QUT Library

halla


73

The TWR (Table 5.35) for the solid electrodes was affected by the use of only two

electrodes for 6 experiments and therefore the results are not completely accurate. The

electroformed electrodes however performed as expected and shows greater TWR as

the machine setting decreases. Compared to the research by Leu et al. [15] (Figure

5.23 and Table 5.36) the TWR is similar for the Electroformed electrodes in that the

TWR increases as the experiments go from roughing to finishing cuts. The solid

electrodes don’t perform as expected as the results were affected by the use of the

same electrodes more than once. Figure 5.22 shows graphically how the different

types of electrodes performed across the different machine settings.

The accuracy of TWR only needed to be down to 0.1 % to get a reasonable

comparison except when there was no measurable TWR for some of the solid

electrodes. Where the TWR did not register a figure the reason was because the scales

didn’t measure any change in mass. If more accurate scales were used to measure the

change in mass the result would still be so small that the resulting TWR would be

insignificant in the comparisons anyway.

Table 5.35 – TWR Comparison for different electrodes at various settings

TWR C170 C170 C140 C140 C110 C110 Electroformed Base 1.804 2.122 1.375 2.410 23.857 12.000 Electroformed Cone 0.672 10.750 1.689 1.183 3.437 10.727 Electroformed Triangle 1.994 1.825 1.746 1.957 7.879 2.633 Solid Base 1.299 1.220 0.654 0.000 1.754 1.282 Solid Cone 1.919 1.163 1.190 1.277 0.000 0.893 Solid Triangle 2.831 0.317 2.286 0.152 0.000 0.893

74

TWR Comparison

0.000

5.000

10.000

15.000

20.000

25.000

30.000

100 110 120 130 140 150 160 170 180


Perc

enta

ge %

Electroformed Electrodes Solid Electrodes Electroformed Electrodes TrendSolid Electrodes Trend

Figure 5.22 – TWR Comparison

Table 5.36 – TWR Comparison for different electrodes at various settings for research

by Leu, Yang and Yao [15]

halla


75

Figure 5.23 – TWR Comparison for research by Leu, Yang and Yao [15]

Therefore as shown in all comparison graphs, the solid electrodes have out performed

the electroformed electrodes in almost every aspect of measurable performance. The

overall results of the electrodes is similar in comparison to the research completed by

Leu et al., Jensen et al. and Yarlagadda et al. [15, 16, 18].

halla


76

6.0 CONCLUSIONS

Manufacture of three different shapes of electrodes in three different manufacturing

methods was achieved. The solid copper and electroformed copper electrodes were

manufactured successfully to the experimental stage however the spray metal

electrodes were unusable.

The experiments with the solid electrodes and electroformed electrodes were

conducted with success at three different machines setting and comparisons were able

to be made. The solid electrodes consistently performed better than the electroformed

electrodes at all machine settings as shown in the summary graphs of the performances

in Machining Time, MRR and TWR.

The major problems encountered with the electroformed electrodes included:

• problems with setup and conductivity,

• shell thickness is hard to control and cavities are difficult to build evenly,

• the electroformed shells are easily damaged,

• the backing material doesn’t have the same conductivity as the copper,

• the copper shells are prone to warping under thermal stress,

• delamination is possible,

Although the solid electrode has out performed the electroformed electrodes in the

majority of the experiments, the solid electrodes are much more expensive to produce.

The standard workshop is more likely to have a machining centre to machine solid

electrodes as opposed to an electroplating system to produce electroformed electrodes.

So the convenience of the solid electrodes will often out way the use of electroformed

electrodes.

The cost of electrodes becomes a major factor as soon as the electrode manufacturing

process becomes more comparable. Even though the solid electrodes out performed

the electroformed and spray metal electrodes, the cost of manufacture plays a vital role

in the tooling process. This research has shown that the cost of solid electrodes is

77

$810 each which is six times that of electroformed and spray metal electrodes at $130

each.

Solid electrodes take approximately six hours to produce where as a single

electroformed electrode will take up to 50 hours to produce. The cost of production is

sometimes not the critical factor when rapid tooling is required. For low numbers of

electrodes it is probably more economical in terms of time to use traditional

machining. However when a large number of electrodes are required, electroforming

will take a similar amount of time to produce one electrode as it will take to produce

an infinite number of electrodes and therefore becoming faster as long as more than 10

electrodes are required..

The research has given similar results to research done by Leu et al. [15], Jensen et al.

[16] and Arthur et al. [14] in that the traditionally produced electrodes performed in a

similar manner to the non-traditional (electroformed) electrodes. If the electroformed

electrodes could be produced with a much more even shell thickness it might reduce

the erratic performance of the electroformed electrodes. Although the electroformed

electrodes performed on average comparable to the solid electrodes there seemed to be

a greater difference between the best and worst performances of the electrodes at each

machine setting.

It is recommended that more refinements need to be done on the electroforming

process to get a greater understanding of the performance characteristics of the

electrodes. Also a greater number of experiments need to be conducted to prove the

repeatability of the electroformed electrodes. Leu et al. [15] conducted eight

experiments at each machining level and others like Arthur et al. [14] conducted over

72 experiments in Fractional Factorial Experiments and Taguchi methods to optimise

the parameters for MRR and the same amount of experiments would be needed to

optimise TWR and Ra. Optimising the machine parameters using Fractional Factorial

Experiments and Taguchi methods is a way that research could promote the use of

electroformed electrodes.

The electroforming process could be a viable option for the EDM process if the

electrodes could be produced more robust and consistent shell thickness. Problems

78

with the shell thickness produced warping and delamination on some of the larger flat

surfaces. With greater control over the wall thickness and greater heat conductivity of

the backing material would give better performance of the electroformed electrodes.

With more investigation into spray metal applications and capabilities it would prove

to be a promising method of electrode manufacture. This project was unable to apply

the time and resources needed to research spray metal to the degree that would be

needed to get the process to a usable standard.

Other areas in EDM that could benefit from more research include:

• Flushing systems for deep cavities,

• Conductive backing materials for the electrode shells,

• Setup and tooling for the electrode attachment to the EDM tool

post to increase the conductivity,

• And investigation into the thermal stresses occurring in the

electroformed electrode shells and backing material.

79

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84

Appendix

85

16.0

00

12.0

00

8.00

0

4.00

0

0.00

0

-4.0

00

-8.0

00

-12.

000

-16.

000

16.000

10.000

4.000

-2.000

-8.000-14.000

-0.150

-0.100

-0.050

0.000

0.050

0.100

0.150

0.200

0.250

Height (mm)

Length (mm)

Width (mm)

Electrode Wear SC1a-b

Figure A.1 - Cone Electrode Wear Experiment 1 - Solid Electrode

86

16.0

00

12.0

00

8.00

0

4.00

0

0.00

0

-4.0

00

-8.0

00

-12.

000

-16.

000

16.000

10.000

4.000

-2.000

-8.000-14.000

-0.150

-0.100

-0.050

0.000

0.050

0.100

0.150

0.200

0.250

Height (mm)

Length (mm)

Width (mm)

Electrode Wear EC1a-b

Figure A.2 - Cone Electrode Wear Experiment 1 - Electroformed Electrode

87

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

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-16.000

-10.000

-4.000

2.000

8.00014.000

-1.000

-0.500

0.000

0.500

1.000

1.500

2.000

2.500

3.000

3.500

Height (mm)

Length (mm)

Width (mm)

Electrode Wear ST1a-b

Figure A.3 – Triangle Electrode Wear Experiment 1 - Solid Electrode

88

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

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16.0

00

-16.000

-10.000

-4.000

2.000

8.00014.000

-1.000

-0.500

0.000

0.500

1.000

1.500

2.000

2.500

3.000

3.500

Height (mm)

Length (mm)

Width (mm)

Electrode Wear ET1

Figure A.4 – Triangle Electrode Wear Experiment 1 - Electroformed Electrode

89

-26.

000

-22.

000

-18.

000

-14.

000

-10.

000

-6.0

00

-2.0

00

2.00

0

6.00

0

10.0

00

14.0

00

18.0

00

22.0

00

26.0

00

-22.000

-14.000

-6.0002.000

10.00018.000

-0.500

0.000

0.500

1.000

1.500

2.000

2.500

3.000

3.500

Height (mm)

Length (mm)

Width (mm)

Material Removed FB1 a-b

Figure A.5 – Base Work Pieces Machined by Solid Electrode compared to Electroformed Electrode - Solid Electrode Work Piece

90

-26.

000

-22.

000

-18.

000

-14.

000

-10.

000

-6.0

00

-2.0

00

2.00

0

6.00

0

10.0

00

14.0

00

18.0

00

22.0

00

26.0

00

-22.000

-14.000

-6.0002.000

10.00018.000

-0.500

0.000

0.500

1.000

1.500

2.000

2.500

3.000

3.500

Height (mm)

Length (mm)

Width (mm)

Material Removed FB2 a-b

Figure A.6 – Base Work Pieces Machined by Solid Electrode compared to Electroformed Electrode - Electroformed Electrode Work Piece

91

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

-20.000

-12.000

-4.000

4.000

12.00020.000

-1.000

0.000

1.000

2.000

3.000

4.000

5.000

6.000

Height (mm)

Length (mm)

Width (mm)

Material Removed FC3 a-b

Figure A.7 – Cone Work Pieces Machined by Solid Electrode compared to Electroformed Electrode - Solid Electrode Work Piece

92

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

-20.000

-12.000

-4.000

4.000

12.00020.000

-1.000

0.000

1.000

2.000

3.000

4.000

5.000

6.000

Height (mm)

Length (mm)

Width (mm)

Material Removed FC2 a-b

Figure A.8 – Cone Work Pieces Machined by Solid Electrode compared to Electroformed Electrode - Electroformed Electrode Work Piece

93

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

-20.000

-12.000

-4.000

4.000

12.00020.000

-5.000

0.000

5.000

10.000

15.000

20.000

25.000

Height (mm)

Length (mm)

Width (mm)

Workpiece FT2a-b

Figure A.9 – Triangle Work Pieces Machined by Solid Electrode compared to Electroformed Electrode - Solid Electrode Work Piece

94

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

-20.000

-12.000

-4.000

4.000

12.00020.000

-5.000

0.000

5.000

10.000

15.000

20.000

25.000

Height (mm)

Length (mm)

Width (mm)

Workpiece FT1a-b

Figure A.10 – Triangle Work Pieces Machined by Solid Electrode compared to Electroformed Electrode - Electroformed Electrode Work Piece

95

-24.

000

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

24.0

00

-20.000

-12.000

-4.000

4.00012.000

20.000

-0.500

-0.400

-0.300

-0.200

-0.100

0.000

0.100

0.200

0.300

0.400

0.500

Height (mm)

Length (mm)

Width (mm)

Electrode Wear SB2 b-c

Figure A.11 – Base Electrode Wear Experiment 2 - Solid Electrode

96

-24.

000

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

24.0

00

-20.000

-12.000

-4.000

4.00012.000

20.000

-0.500

-0.400

-0.300

-0.200

-0.100

0.000

0.100

0.200

0.300

0.400

0.500

Height (mm)

Length (mm)

Width (mm)

Electrode Wear EB2

Figure A.12 – Base Electrode Wear Experiment 2 - Electroformed Electrode

97

16.0

00

12.0

00

8.00

0

4.00

0

0.00

0

-4.0

00

-8.0

00

-12.

000

-16.

000

16.000

10.000

4.000

-2.000

-8.000-14.000

-0.600

-0.400

-0.200

0.000

0.200

0.400

0.600

Height (mm)

Length (mm)

Width (mm)

Electrode Wear SC1b-c

Figure A.13 – Cone Electrode Wear Experiment 2 - Solid Electrode

98

16.0

00

12.0

00

8.00

0

4.00

0

0.00

0

-4.0

00

-8.0

00

-12.

000

-16.

000

16.000

10.000

4.000

-2.000

-8.000-14.000

-0.600

-0.400

-0.200

0.000

0.200

0.400

0.600

Height (mm)

Length (mm)

Width (mm)

Electrode Wear EC2

Figure A.14 – Cone Electrode Wear Experiment 2 - Electroformed Electrode

99

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

-16.000

-10.000

-4.000

2.000

8.00014.000

-0.800

-0.600

-0.400

-0.200

0.000

0.200

0.400

0.600

0.800

Height (mm)

Length (mm)

Width (mm)

Electrode Wear ST1b-c


100

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

-16.000

-10.000

-4.000

2.0008.000

14.000

-0.800

-0.600

-0.400

-0.200

0.000

0.200

0.400

0.600

0.800

Height (mm)

Length (mm)

Width (mm)

Electrode Wear ET2


101

-26.

000

-22.

000

-18.

000

-14.

000

-10.

000

-6.0

00

-2.0

00

2.00

0

6.00

0

10.0

00

14.0

00

18.0

00

22.0

00

26.0

00

-22.000

-14.000

-6.0002.000

10.00018.000

-2.000

0.000

2.000

4.000

6.000

8.000

10.000

12.000

14.000

16.000

18.000

Height (mm)

Length (mm)

Width (mm)

Material Removed FB1 b-c

Figure A.17 – Base Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 2 - Solid Electrode Work Piece

102

-26.

000

-22.

000

-18.

000

-14.

000

-10.

000

-6.0

00

-2.0

00

2.00

0

6.00

0

10.0

00

14.0

00

18.0

00

22.0

00

26.0

00

-22.000

-14.000

-6.0002.000

10.00018.000

-2.000

0.000

2.000

4.000

6.000

8.000

10.000

12.000

14.000

16.000

18.000

Height (mm)

Length (mm)

Width (mm)

Material Removed FB2 b-c

Figure A.18 – Base Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 2 - Electroformed Electrode

Work Piece

103

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

-20.000

-12.000

-4.000

4.000

12.00020.000

-0.200

0.000

0.200

0.400

0.600

0.800

1.000

1.200

Height (mm)

Length (mm)

Width (mm)

Material Removed FC3 b-c

Figure A.19 – Cone Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 2 - Solid Electrode Work

Piece

104

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

-20.000

-12.000

-4.000

4.000

12.00020.000

-0.200

0.000

0.200

0.400

0.600

0.800

1.000

1.200

Height (mm)

Length (mm)

Width (mm)

Material Removed FC2 b-c

Figure A.20 – Cone Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 2 - Electroformed Electrode

Work Piece

105

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

-20.000

-12.000

-4.000

4.000

12.00020.000

-0.500

0.000

0.500

1.000

1.500

2.000

2.500

3.000

3.500

4.000

Height (mm)

Length (mm)

Width (mm)

Workpiece FT2 b-c

Figure A.21 – Triangle Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 2 - Solid Electrode Work

Piece

106

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

-20.000

-12.000

-4.000

4.000

12.00020.000

-0.500

0.000

0.500

1.000

1.500

2.000

2.500

3.000

3.500

4.000

Height (mm)

Length (mm)

Width (mm)

Workpiece FT1 b-c

Figure A.22 – Triangle Work Pieces Machined by Solid Electrode compared to Electroformed Electrode Experiment 2 - Electroformed

Electrode Work Piece

107

-24.

000

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

24.0

00

-20.000

-12.000

-4.000

4.00012.000

20.000

-1.200

-1.000

-0.800

-0.600

-0.400

-0.200

0.000

0.200

0.400

0.600

0.800

Height (mm)

Length (mm)

Width (mm)

Electrode Wear SB2 c-d


108

-24.

000

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

24.0

00

-20.000

-12.000

-4.000

4.00012.000

20.000

-1.200

-1.000

-0.800

-0.600

-0.400

-0.200

0.000

0.200

0.400

0.600

0.800

Height (mm)

Length (mm)

Width (mm)

Tool Wear EB3


109

16.0

00

12.0

00

8.00

0

4.00

0

0.00

0

-4.0

00

-8.0

00

-12.

000

-16.

000

16.000

10.000

4.000

-2.000

-8.000-14.000

-0.250

-0.200

-0.150

-0.100

-0.050

0.000

0.050

0.100

0.150

0.200

0.250

Height (mm)

Length (mm)

Width (mm)

Electrode Wear SC1c-d


110

16 14 12 10 8 6 4 2 0 -2 -4 -6 -8 -10 -12 -14 -1616.000

10.000

4.000

-2.000

-8.000-14.000

-0.250

-0.200

-0.150

-0.100

-0.050

0.000

0.050

0.100

0.150

0.200

0.250

Height (mm)

Length (mm)

Width (mm)

Electrode Wear EC3


111

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

-16.000

-10.000

-4.000

2.000

8.00014.000

-1.500

-1.000

-0.500

0.000

0.500

1.000

1.500

2.000

Heigth (mm)

Length (mm)

Width (mm)

Electrode Wear ST1c-d


112

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

-16.000

-10.000

-4.000

2.000

8.00014.000

-1.500

-1.000

-0.500

0.000

0.500

1.000

1.500

2.000

Height (mm)

Length (mm)

Width (mm)

Electrode Wear ET3


113

-26.

000

-22.

000

-18.

000

-14.

000

-10.

000

-6.0

00

-2.0

00

2.00

0

6.00

0

10.0

00

14.0

00

18.0

00

22.0

00

26.0

00

-22.000

-14.000

-6.0002.000

10.00018.000

-1.500

-1.000

-0.500

0.000

0.500

1.000

1.500

2.000

2.500

Height (mm)

Length (mm)

Width (mm)

Material Removed FB1 c-d


114

-26.

000

-22.

000

-18.

000

-14.

000

-10.

000

-6.0

00

-2.0

00

2.00

0

6.00

0

10.0

00

14.0

00

18.0

00

22.0

00

26.0

00

-22.000

-14.000

-6.0002.000

10.00018.000

-1.500

-1.000

-0.500

0.000

0.500

1.000

1.500

2.000

2.500

Height (mm)

Length (mm)

Width (mm)

Material Removed FB2 c-d


Work Piece

115

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

-20.000

-12.000

-4.000

4.000

12.00020.000

-0.500

0.000

0.500

1.000

1.500

2.000

2.500

Height (mm)

Length (mm)

Width (mm)

Material Removed FC3 c-d


Piece

116

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

-20.000

-12.000

-4.000

4.000

12.00020.000

-0.500

0.000

0.500

1.000

1.500

2.000

2.500

Height (mm)

Length (mm)

Width (mm)

Material Removed FC2 c-d


Work Piece

117

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

-20.000

-12.000

-4.000

4.000

12.00020.000

-0.500

0.000

0.500

1.000

1.500

2.000

2.500

3.000

3.500

4.000

4.500

Height (mm)

Length (mm)

Width (mm)

Workpiece FT2 c-d


Piece

118

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

-20.000

-12.000

-4.000

4.000

12.00020.000

-0.500

0.000

0.500

1.000

1.500

2.000

2.500

3.000

3.500

4.000

4.500

Height (mm)

Length (mm)

Width (mm)

Workpiece FT1 c-d



119

-24.

000

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

24.0

00

-20.000

-12.000

-4.000

4.00012.000

20.000

-1.500

-1.000

-0.500

0.000

0.500

1.000

Height (mm)

Length (mm)

Width (mm)

Electrode Wear SB2 d-e


120

-24.

000

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

24.0

00

-20.000

-12.000

-4.000

4.00012.000

20.000

-1.500

-1.000

-0.500

0.000

0.500

1.000

Height (mm)

Length (mm)

Width (mm)

Tool Wear EB4


121

16.0

00

12.0

00

8.00

0

4.00

0

0.00

0

-4.0

00

-8.0

00

-12.

000

-16.

000

16.000

10.000

4.000

-2.000

-8.000-14.000

-0.150

-0.100

-0.050

0.000

0.050

0.100

0.150

Height (mm)

Length (mm)

Width (mm)

Electrode Wear SC1 d-e


122

16.0

00

12.0

00

8.00

0

4.00

0

0.00

0

-4.0

00

-8.0

00

-12.

000

-16.

000

16.000

10.000

4.000

-2.000

-8.000-14.000

-0.150

-0.100

-0.050

0.000

0.050

0.100

0.150

Height (mm)

Length (mm)

Width (mm)

Electrode Wear EC4


123

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

-16.000

-10.000

-4.000

2.000

8.00014.000

-1.000

-0.500

0.000

0.500

1.000

1.500

Height (mm)

Length (mm)

Width (mm)

Electrode Wear ST1d-e


124

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

-16.000

-10.000

-4.000

2.000

8.00014.000

-1.000

-0.500

0.000

0.500

1.000

1.500

Height (mm)

Length (mm)

Width (mm)

Electrode Wear ET4


125

-26.

000

-22.

000

-18.

000

-14.

000

-10.

000

-6.0

00

-2.0

00

2.00

0

6.00

0

10.0

00

14.0

00

18.0

00

22.0

00

26.0

00

-22.000

-14.000

-6.0002.000

10.00018.000

-3.000

-1.000

1.000

3.000

5.000

7.000

9.000

11.000

13.000

15.000

Height (mm)

Length (mm)

Width (mm)

Material Removed FB1 d-e


126

-26.

000

-22.

000

-18.

000

-14.

000

-10.

000

-6.0

00

-2.0

00

2.00

0

6.00

0

10.0

00

14.0

00

18.0

00

22.0

00

26.0

00

-22.000

-14.000

-6.0002.000

10.00018.000

-3.000

-1.000

1.000

3.000

5.000

7.000

9.000

11.000

13.000

15.000

Height (mm)

Length (mm)

Width (mm)

Material Removed FB2 d-e


Work Piece

127

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

-20.000

-12.000

-4.000

4.000

12.00020.000

-0.500

0.000

0.500

1.000

1.500

2.000

2.500

Height (mm)

Length (mm)

Width (mm)

Material Removed FC3 d-e


Piece

128

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

-20.000

-12.000

-4.000

4.000

12.00020.000

-0.500

0.000

0.500

1.000

1.500

2.000

2.500

Height (mm)

Length (mm)

Width (mm)

Material Removed FC2 d-e


Work Piece

129

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

-20.000

-12.000

-4.000

4.000

12.00020.000

-0.500

0.000

0.500

1.000

1.500

2.000

2.500

3.000

3.500

Height (mm)

Length (mm)

Width (mm)

Workpiece FT2 d-e


Piece

130

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

-20.000

-12.000

-4.000

4.000

12.00020.000

-0.500

0.000

0.500

1.000

1.500

2.000

2.500

3.000

3.500

Height (mm)

Length (mm)

Width (mm)

Workpiece FT1 d-e



131

-24.

000

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

24.0

00

-20.000

-12.000

-4.000

4.00012.000

20.000

-0.800

-0.600

-0.400

-0.200

0.000

0.200

0.400

0.600

Height (mm)

Length (mm)

Width (mm)

Electrode Wear SB1 a-b


132

-24.

000

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

24.0

00

-20.000

-12.000

-4.000

4.00012.000

20.000

-0.800

-0.600

-0.400

-0.200

0.000

0.200

0.400

0.600

Height (mm)

Length (mm)

Width (mm)

Tool Wear EB5


133

16.0

00

12.0

00

8.00

0

4.00

0

0.00

0

-4.0

00

-8.0

00

-12.

000

-16.

000

16.000

10.000

4.000

-2.000

-8.000-14.000

-0.200

-0.100

0.000

0.100

0.200

0.300

0.400

Height (mm)

Length (mm)

Width (mm)

Electrode Wear SC2a-b


134

16.0

00

12.0

00

8.00

0

4.00

0

0.00

0

-4.0

00

-8.0

00

-12.

000

-16.

000

16.000

10.000

4.000

-2.000

-8.000-14.000

-0.200

-0.100

0.000

0.100

0.200

0.300

0.400

Height (mm)

Length (mm)

Width (mm)

Electrode Wear EC5


135

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

-16.000

-10.000

-4.000

2.000

8.00014.000

-0.600

-0.400

-0.200

0.000

0.200

0.400

0.600

0.800

Height (mm)

Length (mm)

Width (mm)

Electrode Wear ST2a-b


136

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

-16.000

-10.000

-4.000

2.000

8.00014.000

-0.600

-0.400

-0.200

0.000

0.200

0.400

0.600

0.800

Height (mm)

Length (mm)

Width (mm)

Electrode Wear ET5


137

-26.

000

-22.

000

-18.

000

-14.

000

-10.

000

-6.0

00

-2.0

00

2.00

0

6.00

0

10.0

00

14.0

00

18.0

00

22.0

00

26.0

00

-22.000

-14.000

-6.0002.000

10.00018.000

-1.500

-1.000

-0.500

0.000

0.500

1.000

1.500

Height (mm)

Length (mm)

Width (mm)

Material Removed FB1 e-f


138

-26.

000

-22.

000

-18.

000

-14.

000

-10.

000

-6.0

00

-2.0

00

2.00

0

6.00

0

10.0

00

14.0

00

18.0

00

22.0

00

26.0

00

-22.000

-14.000

-6.0002.000

10.00018.000

-1.500

-1.000

-0.500

0.000

0.500

1.000

1.500

Height (mm)

Length (mm)

Width (mm)

Material Removed FB2 e-f


Work Piece

139

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

-20.000

-12.000

-4.000

4.000

12.00020.000

-0.400

-0.200

0.000

0.200

0.400

0.600

0.800

1.000

1.200

1.400

1.600

Height (mm)

Length (mm)

Width (mm)

Material Removed FC3 e-f


Piece

140

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

-20.000

-12.000

-4.000

4.000

12.00020.000

-0.400

-0.200

0.000

0.200

0.400

0.600

0.800

1.000

1.200

1.400

1.600

Height (mm)

Length (mm)

Width (mm)

Material Removed FC2 e-f


Work Piece

141

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

-20.000

-12.000

-4.000

4.000

12.00020.000

-7.000

-5.000

-3.000

-1.000

1.000

3.000

5.000

7.000

Height (mm)

Length (mm)

Width (mm)

Workpiece FT2 e-f


Piece

142

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

-20.000

-12.000

-4.000

4.000

12.00020.000

-7.000

-5.000

-3.000

-1.000

1.000

3.000

5.000

7.000

Height (mm)

Length (mm)

Width (mm)

Workpiece FT1 e-f



143

-24.

000

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

24.0

00

-20.000

-12.000

-4.000

4.00012.000

20.000

-2.500

-2.000

-1.500

-1.000

-0.500

0.000

0.500

1.000

Height (mm)

Length (mm)

Width (mm)

Electrode Wear SB1 b-c


144

-24.

000

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

24.0

00

-20.000

-12.000

-4.000

4.00012.000

20.000

-2.500

-2.000

-1.500

-1.000

-0.500

0.000

0.500

1.000

Height (mm)

Length (mm)

Width (mm)

Tool Wear EB6


145

16.0

00

12.0

00

8.00

0

4.00

0

0.00

0

-4.0

00

-8.0

00

-12.

000

-16.

000

16.000

10.000

4.000

-2.000

-8.000-14.000

-0.100

-0.080

-0.060

-0.040

-0.020

0.000

0.020

0.040

0.060

0.080

0.100

0.120

Height (mm)

Length (mm)

Width (mm)

Electrode Wear SC2b-c


146

16.0

00

12.0

00

8.00

0

4.00

0

0.00

0

-4.0

00

-8.0

00

-12.

000

-16.

000

16.000

10.000

4.000

-2.000

-8.000-14.000

-0.100

-0.080

-0.060

-0.040

-0.020

0.000

0.020

0.040

0.060

0.080

0.100

0.120

Height (mm)

Length (mm)

Width (mm)

Electrode Wear EC6


147

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

-16.000

-10.000

-4.000

2.000

8.00014.000

-1.000

-0.800

-0.600

-0.400

-0.200

0.000

0.200

0.400

0.600

0.800

Heigth (mm)

Length (mm)

Width (mm)

Electrode Wear ST2b-c


148

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

-16.000

-10.000

-4.000

2.000

8.00014.000

-1.000

-0.800

-0.600

-0.400

-0.200

0.000

0.200

0.400

0.600

0.800

Height (mm)

Length (mm)

Width (mm)

Electrode Wear ET6


149

-26.

000

-22.

000

-18.

000

-14.

000

-10.

000

-6.0

00

-2.0

00

2.00

0

6.00

0

10.0

00

14.0

00

18.0

00

22.0

00

26.0

00

-22.000

-14.000

-6.0002.000

10.00018.000

-1.500

-1.000

-0.500

0.000

0.500

1.000

1.500

2.000

2.500

3.000

Height (mm)

Length (mm)

Width (mm)

Material Removed FB1 f-g


150

-26.

000

-22.

000

-18.

000

-14.

000

-10.

000

-6.0

00

-2.0

00

2.00

0

6.00

0

10.0

00

14.0

00

18.0

00

22.0

00

26.0

00

-22.000

-14.000

-6.0002.000

10.00018.000

-1.500

-1.000

-0.500

0.000

0.500

1.000

1.500

2.000

2.500

3.000

Height (mm)

Length (mm)

Width (mm)

Material Removed FB2 f-g


Work Piece

151

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

-20.000

-12.000

-4.000

4.000

12.00020.000

-0.200

0.000

0.200

0.400

0.600

0.800

1.000

1.200

Height (mm)

Length (mm)

Width (mm)

Material Removed FC3 f-g


Piece

152

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

-20.000

-12.000

-4.000

4.000

12.00020.000

-0.200

0.000

0.200

0.400

0.600

0.800

1.000

1.200

Height (mm)

Length (mm)

Width (mm)

Material Removed FC2 f-g


Work Piece

153

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

-20.000

-12.000

-4.000

4.000

12.00020.000

-6.000

-4.000

-2.000

0.000

2.000

4.000

6.000

8.000

Height (mm)

Length (mm)

Width (mm)

Workpiece FT2 f-g


Piece

154

-20.

000

-16.

000

-12.

000

-8.0

00

-4.0

00

0.00

0

4.00

0

8.00

0

12.0

00

16.0

00

20.0

00

-20.000

-12.000

-4.000

4.000

12.00020.000

-6.000

-4.000

-2.000

0.000

2.000

4.000

6.000

8.000

Height (mm)

Length (mm)

Width (mm)

Workpiece FT1 f-g



P EVALUATION OF APID TOOLING FOR ELECTRIC DISCHARGE...

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Transcript of P EVALUATION OF APID TOOLING FOR ELECTRIC DISCHARGE...