1.0 ABSTRACT

Machining is an important manufacturing process that is used in a wide range of

applications. From aerospace applications to the manufacturing of energy systems and

medical robots, we see a major reliance on machining. In this project we focus on gaining an

improved understanding of the mechanics of machining and the different factors that

contribute to part quality. We acquired primary machine shop skills that provided us an

opportunity to mill and drill a class of components to specified dimensions and tolerances.

For each component, we created a detailed engineering working drawing that helped to

shape and construct all the operations and procedures that must be undertaken and

controlled to attain component machining without any breakdown or failure. Through

hands-on machining, we discovered many different factors involved in milling, drilling, and

the effects they exhibited on the tolerance and surface finish of a part. The main relevant

factors that we examined were tool selection, speeds, feeds, and material selection. The

extent to which these factors can influence machining is presented.

2.0 TABLE OF CONTENT

1.0 ABSTRACT..................................................................................................................................1

2.0 TABLE OF CONTENT...................................................................................................................2

3.0 LIST OF FIGURES.........................................................................................................................3

4.0 TITLE..........................................................................................................................................4

5.0 INTRODUCTION.........................................................................................................................4

6.0 OBJECTIVES................................................................................................................................6

7.0 THEORY......................................................................................................................................6

8.0 APPARATUS...............................................................................................................................8

9.0 PROCEDURE.............................................................................................................................11

10.0 DISCUSSION.............................................................................................................................13

11.0 CONCLUSION...........................................................................................................................14

12.0 RECOMMENDATIONS..............................................................................................................15

13.0 REFERENCES.............................................................................................................................16

3.0 LIST OF FIGURESFigure 1..................................................................................................................................................6Figure 2..................................................................................................................................................8Figure 3..................................................................................................................................................8Figure 4..................................................................................................................................................9Figure 5................................................................................................................................................10Figure 6: the finished product.............................................................................................................12

4.0 TITLE

CNC Milling (Non Traditional Machining)

5.0 INTRODUCTION

A non-traditional manufacturing process is defined as a group of processes that remove

accessed material by various technique based on different sources of energy. The cutting

source may in the form of mechanical, thermal, electrical or chemical energy or

combinations of these energies without any direct contact of sharp cutting as in traditional

machining. Extremely hard and brittle materials are difficult to machine by traditional

machining process such as turning, drilling, shaping and milling. Non-traditional machining

processes are graphed in advanced manufacturing processes. It is employed when

traditional machining processes are not feasible and due to the certain satisfactory

justification to special reasons.

CNC Milling

CNC Milling is a specific form of computer numerical controlled (CNC) machining. During

CNC milling the computer translates the design into instruction on how the drill needs to

move to create shape. Milling itself is a machining process similar to both drilling and

cutting, and able to achieve many of the operations performed by cutting and drilling

machines. Like drilling, milling uses a rotating cylindrical cutting tools. However, the cutter in

the milling machine is able to move along multiple axes, and can create a variety of shapes,

slots and holes. In addition, the work-piece is often moved across the milling tools in

different directions, unlike the single axis motion of the drill.

CNC milling devices are the most widely used type of CNC machine. Typically, they are

grouped by the number of the axes on which they operate, which are labelled with various

letters. X and Y designate horizontal movement of the work-piece (forward-and-back and

side-to-side on a flat plane). Z represents vertical or up-and-down movement while W

represents diagonal movement across a vertical plane. Most machines offer from 3 to 5

axes, providing performance along at least X,Y and Z axes.

Advanced machines, such as 5-axis milling centres required CAM programming for optimal

performance due to the incredibly complex geometries involved in the machining process.

These devices are extremely useful because they are able to produce shapes that would be

nearly impossible using manual tooling methods. Most CNC milling machines also integrate

a device for pumping cutting fluid to the cutting tool during machining. Cutting fluids are

used in metal machining for variety of reasons such as improving tools life, reducing work

piece thermal deformation, improving surface finish and flushing away chips from the

cutting zone

G-CODE

CODE FUNCTION

G00 Rapid transverse

G01 Linear interpolation

G02 Circular interpolation (clockwise)

G03 Circular interpolation (counterclockwise)

G81 Drilling cycle

G90 Absolute positioning

M-CODE

CODE FUNCTION

M00 Program stop

M01 Optional program stop

M02 Program end

M03 Spindle on clockwise

M04 Spindle on counterclockwise

M06 Tool change

M08 Coolant on

6.0 OBJECTIVES

To design a basic NC program for CNC Milling

To machine a product using the CNC Milling

7.0 THEORY

Characteristic of CNC Milling Machine Tool Work part machining on CNC machine tools

require controllable and adjustable in feed axes which are runs by servo motors

independent of each other. CNC milling machine on the other hand have at least 3

controllable or adjustable feed axes marked as X,Y and Z.

Figure 1

Controllable NC axes on a Milling Machine

Machine Coordinate System

The machine coordinate system of CNC machine tools is defined by the

manufacturer and cannot be changed.

The point of origin for this machine coordinate system also called machine zero

point, M cannot be shifted in its location.

Work Part Coordinate System

The work part coordinate system is defined by the programmer and can be changed. The

location of the point of origin for the work part coordinate system, also called work part

zero point W, can be specified as desired. The design of CNC machine specifies the definition

of the respective coordinate system. Correspondingly, the Z axis is specified as the working

spindle (tool carrier) in CNC milling machines whereby the positive Z directions run from

the work part upwards to the tools. The X axis and the Y axis are usually parallel to the

clamping plane of the work part. When standing in front of the machine, the positive X

direction runs to the right and the Y axis runs away from the viewer. The zero point of the

coordinate system is recommended to be placed on the outer edge of the work part.

Structure of an NC-Block

Unlike the conventional milling machine , a modern machine tool will be equipped with a

numerical control system. The machining of a work part can be executed automatically,

provided that each machining cycle has been described in a “language” (code) which can be

read by the control system. The total of coded descriptions relating to work part is called

NC-programs.

8.0 APPARATUS

APPARATUS

Figure 2

Figure 3

1. CNC centroid milling machine2. Workpiece3. Machine control unit (MCU)4. Spanner5. Coolant (oil)

1

2

3

4

5

INDUSTRIAL APPARATUS

1) CNC Bed Type Ram Milling Machine

The CNC Bed Type Ram milling machine is built in with the center ram and bed type where it have high rigidity, beautiful configuration and easy to operate.

It is also contain with 5 axis which contains of two swivel axis of universal head automatic swivel, C axis (horizontal axis) automatic indexing and 45 degree of the milling head automatic location for vertical axis and horizontal milling to exchange automatically.

Advantages DisadvantagesCapable of processing complex cutting tool High costUnparallel structural stiffness Less worker use can lead to the

unemploymentVery high precision when machining large component

Can be operate by inexperience worker and it will lead to loses in old skill of operating the machine

Very high material removal capacity for wide range of metal material from cast iron to steel alloys

The professional skilled worker will continue less in a year which lead to the loss of engineering skill

Figure 4

Table Size 690 x 1590 mm

X axis travel1600/2500/3000 mm

Y axis Travel 900/1250 mm

Z axis Travel 400/600 mm

Max. capacity of load on table

2000 kgs.

Spindle speed 4-2000 rpm

Spindle type BT-50

Feed 0-5000 mm/min.

Rapid 5000 mm/min.

Spindle Power 7.5 KW

2) CNC Lathe Machine-GENOS-I1300 type

Specification

Max Turning Diameter mm (in) Ø 300 (Ø 11.81)

Spindle Nose Type JIS A2-8 [A2-6]

Speed Range min⁻¹ 25~3,000 [4,500]

Power 30 min kW (hp) 15 (20)

Power cont. kW (hp) 11 (15)

Rapid Traverse m (in)/min 20/25 (787/984)

Figure 5

Advantages Disadvantages

Multifunction lathe machine

High cost due to high machining tool and equipment

Provide the stability, rigidity and accuracy for variety application

Not suitable for cutting large scale product

Affordable and versatility Take a longer time due to the quality of the product produced

9.0 PROCEDURE

EXPERIMENTAL PROCEDURE

1) The design of the product was created using a 3D software , CATIA and we are assigned to create a steering model.

NC PROGRAMMING

1) The NC programming to be used in the CNC milling machine was generated using

Computer Aided Manufacturing (CAM) feature in CATIA software.

2) The rough stock of the design was configured. The length of x, y and z was set

according to the longest length in 3D design which was 60mm, 60mm and 18mm

respectively.

3) The datum of the rough stock was configured to beat one of the top corner of the

rough stock.

4) The part operation was configured. The axis, part and its rough stock was selected.

5) The safety plane of the process was configured to be 6mm above the highest point

of z-axis of the design block.

6) The machining process simulation was configured. The process was divided into two

processes, roughing and finishing. The approach speed,machining speed, retract

speed and spindle spin was configured to be 3000, 1000 and 3000 respectively

7) The quality of the process was set to be ‘rough’.

8) Other setting such as offset, tolerance, axial and tool pathing style were configured

accordingly.

9) The simulation of the process was generated.

10) Steps 6 to 9 were repeated for finishing process where step 7 was replaced with

‘finish’ quality.

11) The estimated process time was generated by the software. The time was about 30

minutes.

12) The NC code was generated using the CATIA software. The format of the code

‘fannc0’ which are required by the faculty laboratory’s CNC milling machine.

13) The produced code, with 1424 lines of command was saved.

CNC MILLING PROCESS

1) The NC code was transferred and loaded into CNC milling machine.

2) The material’s datum was configured manually.

3) The clamping that hold material was checked not to be in the tool’s retract path.

4) The necessary setting such as the tool type was configured.

5) The machine runs a simulation of the process.

6) The milling process was started after all the precautions have been taken.

7) The chip from material was removed constantly.

8) The finished material was cleaned from any chips.

9) The finished product was examined, the quality and dimension of the product was

studied.

Figure 6: the finished product

10.0 DISCUSSION

Based on the result obtain, the work piece is produce from the milling process. What is

milling? Milling is the machining process using rotary cutter to removed material. It is one of

the most operation process used in industry to make a product. There a few type of milling,

and one of the type used in the experiment is Computer Numerical Control (CNC) Milling.

Numerical Control (NC) is the automation of machine tool. So, CNC machine is used to

program coded under computer to the machine tool to operate the system and the

machine. CNC milling can also perform the function of drilling and turning. It is used to move

according to the axes that it’s possess which x, y and z axis.

Today, CNC system is highly automated using Computer Aided Design (CAD) and Computer

Aided Manufacturing (CAM) program. For this experiment CAM program method is used. To

operate the machine, the computer file is produced and interpreted to extract the

command needed. After that, the program is installed into CNC machine for production. The

coding was done because the NC machine cannot read the design directly. The machine will

run according to the coding that has been inserting. The duration of the product based on

the number of the coding inserting. For about 1424 lines coding was inserted in the

programming to make the product in this experiment. About approximately 30 minutes for

the CNC milling machine to complete finish the product that has been design by CATIA

software.

CATIA is a software that used to design products in computer files before installed into CNC

machine .CATIA also can eliminate the human error when design product.

There are lots of advantages of using CNC machine. One of the advantage is higher precision

because machine tool capable to machine at very close tolerance, as small as 0.005 mm. It is

also can machining the complex three dimensional shapes. For example, variety of design

such as the steering car and rim of the car and motorcycle can be made using CNC machine.

The experiment results show that the three complex dimensional shapes are proven can be

produced. Besides, it has better quality because it can maintain constant working condition

for all parts. From the experiment product obtain, we can say that the surface product is

smooth. This is because there are two kind of process occur, roughing and finishing.

Roughing is the process where the work piece is shaping for the first layer. In this case, the

surface of work piece is still rough. It is like sketching in the drawing. After that, finishing

process takes place. This is when the final product has been touch up in order to make

smoother surface.

This experiment occurred when the cutter in dry condition. There are no cooling agents to

cool the work piece and tool. However, the oil is added to the work piece as cooling fluid to

make the milling process run smoother without distraction of the work piece flash. The flash

is stick to the oil that’s why the machine is easy to drill the work piece. The work piece also

has to be holding tightly enough from moving during process occur to prevent any

defection.

There are lots of products has been produce from CNC milling machine in industry. The

product requirement produces in varies industries such as electronic, instrumentation,

medical, microwave, optical and many more.

11.0 CONCLUSION

Regarding to the experiment on using CNC machine to produce a steering wheel using the

prospect material, the product that was produced look a little rough on its surface. Thus,

due to the several factor on the beginning of the designing of the product. The process of

designing the steering start by using CATIA software design to design the initial picture of

the steering that need to be fabricate.

Next, the analysis and the visualization of the product that will be cut were done by the

software. The cutting layer of the product was set up to two types; rouging and finishing. To

get the better surface roughness there are two or three more setting that can be applied

from the software but it will consume a lot of time to produce a fine product with smooth

surface finish. The required time need to finish the product was 30 minutes. Before the

design was transferred to the machine it will be converted to a general coding of the CNC

machine. This process of converted the coding was run automatically by the CAM software.

So, that is one of the different between EDM wire cut and this CNC machine where EDM

wire cut machine, the coding was done manually by the user.

12.0 RECOMMENDATIONS

1. When configuring the size of the livestock, make sure include extra length for

clamping purpose.

2. When selecting tool, make sure to check the smallest gap or edge in the design.

3. The speed, tool tip type, offset distance and tool pathing style can affect the quality

of the product. Trying other configuration could help students to determine the best

configuration.

4. Student must carefully observe the tool’s retract path in the simulation and make

sure the clamp are not the path.

5. The chips produced during milling process should be constantly removed to avoid

surface damage.

13.0 REFERENCES

1. Woodbury, Robert S. (1972)[1960], History of the Milling Machine. In Studies in the

History of Machine Tools, Cambridge, Massachussetts, USA, and London, Egland: MIT

Press, ISBN 978-0-262-73033-4, LCCN 72006354. First published alone as monograph

in 1960.

2. Smid, Peter (2008), CNC Programming Handbook (3rd ed.), New York : Industrial

Press, ISBN 9780831133474, LCCN 2007045901.

3. Mikell P. Groover, Automation, Production Systems and Computer Integrated

Manufacturing, 2nd edition, Prentice Hall, 2001.

4. Mikell P. Groover, Principles of Modern Manufacturing, 5th edition, p.p 480-490,

Wiley, 2011.

5. Mikell P. Groover, Principles of Modern Manufacturing, 5th edition, p.p 876-889,

Wiley, 2011.

6. P. N. Rao, CAD/CAM Principles and Applications, 2nd edition, Mc Graw Hill, 2004.

7. Serope Kalpakjian, W. R. Schmid, Manufacturing Technology and Fundamental,8th

edition , Prentice Hall, 2011.