A

Project Report

On

ASSOCIATION OF DAQ SYSTEM IN CNC MACHINE

FOR MICRO MILLING PROCESS

Submitted in Partial Fulfilment of the Required for the Award of Degree in

Bachelor of Technology

In

Mechanical Engineering

By

Shubham Agrawal (12119077)

Rohit Nath (12119046)

Sumit Kumar (11119081)

Ankit Ojha (11119009)

Niteesh Ram (09119045)

Approved By: Guided By:

Dr. R Salhotra Dr. M. S. Rajput

[Head of Department] [Assistant Professor]

Department of Mechanical Engineering

National Institute of Technology Raipur

2012-2016

2

ACKNOWLEDGEMENT

With great pleasure, we hereby extend our heartiest thanks and deep sense of

indebtedness to Dr.Mridul Singh Rajput , Mechanical Engineering

Department, NIT Raipur; for his guidance and everlasting help which has been

instrumental in completion of this work. It would never be possible for us to

take this project to this level without his innovative ideas and his relentless

support and encouragement.

Our heartiest thanks to Dr. Rahul Salhotra, Head of Mechanical Engineering

Department, NIT Raipur, for his constant encouragement without which we

couldn’t have carried out this project in time.

Further we are also grateful to all our professors of Mechanical Engineering

Department for their teaching, which has helped us at every stage of the

project work.

Shubham Agrawal (12119077)

Rohit Nath (12119046)

Sumit Kumar (11119081)

Ankit Ojha (11119009)

Niteesh Ram (09119045)

3

CERTIFICATE This is to certify that minor project report entitled “ASSOCIATION OF DAQ

SYSTEM IN CNC MACHINE FOR MICRO MILLING PROCESS” submitted, by Rohit

Nath (12119046), Shubham Agrawal (12119077), Sumit kumar (11119081),

Ankit Ojha (11119009), Niteesh Ram (09119045), in partial fulfilment of the

requirement of the degree of the Bachelor of Technology in Mechanical

Engineering at the National Institute of Technology, Raipur, during the

academic year 2015-2016 is a bona-fide record of work carried out under my

guidance and supervision. This certification does not necessarily endorse or

accept any statement made opinion expressed or conclusion drawn as

recorded in this report. However it only signifies the acceptance of report for

the purpose of which it is submitted.

Dr. Mridul Singh Rajput Dr. Rahul Salhotra

Assistant Professor Head of Department

Mechanical Engineering Mechanical Engineering

4

INDEX

TITLE PAGE NO Introduction 5

Literature Review 6

Problem Identification 9

Experimental Setup 10

Experimental Process 19

Outcome 22

Conclusion 25

5

Introduction

Any object you see around yourself goes through rigorous machining process

such as milling, cutting, edging, fabrication etc. Milling process occupies a very

important role in getting the desired final outcome. Milling is the most common

form of machining, a material removal process, which can create a variety of

features on a part by cutting away the unwanted material.

Milling is a cutting process that uses a milling cutter to remove material from

the surface of a workpiece. The milling cutter is a rotary cutting tool, often with

multiple cutting points. As opposed to drilling, where the tool is advanced along

its rotation axis, the cutter in milling is usually moved perpendicular to its axis

so that cutting occurs on the circumference of the cutter. As the milling cutter

enters the workpiece, the cutting edges (flutes or teeth) of the tool repeatedly cut

into and exit from the material, shaving off chips (swarf) from the workpiece

with each pass.

Milling is typically used to produce parts that are not axially symmetric and

have many features, such as holes, slots, pockets, and even three dimensional

surface contours. Parts that are fabricated completely through milling often

include components that are used in limited quantities, perhaps for prototypes,

such as custom designed fasteners or brackets. Another application of milling is

the fabrication of tooling for other processes.

Copper & Its Machining

Copper is a soft, malleable and ductile metal with very high thermal and

electrical conductivity. A freshly exposed surface of pure copper has a reddish-

orange colour. It is used as a conductor of heat and electricity, as a building

material, and as a constituent of various metal alloys. It has Young’s Modulus

of 110-128 Gpa & Brinell Hardness of 235-878 Mpa.

6

What Is Data Acquisition?

Data acquisition (DAQ) is the process of measuring an electrical or physical

phenomenon such as voltage, current, temperature, pressure, or sound with a

computer. A DAQ system consists of sensors, DAQ measurement hardware,

and a computer with programmable software. Compared to traditional

measurement systems, PC-based DAQ systems exploit the processing power,

productivity, display, and connectivity capabilities of industry-standard

computers providing a more powerful, flexible, and cost-effective measurement

solution.

NI ELVIS 2 DAQ SYSTEM

7

Literature Review

After making careful analysis of few journals and previous research papers on

Micro Milling & its characteristics, we have got an insight about the topic and

the following conclusion have been made.

Bang et al. ,has been given that micro stage, PC based control board and air

spindle can be used to produce a low cost milling machine. Various experiments

involving machining of micro blades, micro columns & micro walls shows the

capability of micro milling machine to produce micro parts.

Rahman et al. , Concluded that to identify the major causes affecting the tool

life various experiments have been done on pure Copper. On machining the

pure Cu both spiral and broken chips were formed. The size of the chip varies

but the shape remains same. There was a unique thing observed that the tool life

increases with the increase in depth of cut. There was an increase in tool when

the helix angle was kept 25 degrees. So the tool life depends on helix angle and

depth of cut.

Tansel et al. , stated that it was the experiment based on tool breakage

mechanisms in micro end milling operations. A relationship was found after the

experiment between tool condition and the static part of the feed direction

cutting force. Segmental averages and wavelet transformations were used for

tool breakage prediction. Fatigue and excessive load related micro tool breakage

was effected by usage related stress.

Chae et al. ,investigated on micro cutting operations ,benefits of use of

miniature parts for micro milling process. Smaller footprints, lower power

consumption & higher heat transfer are the benefits which are obtained by using

miniature components. Micro-mechanical machining is well suited to support

the development of micro-injection moulds because of its promise for accurate,

low cost, small batch size processes of 3D moulds using ferrous alloys.

Tansel et al. ,stated that it was an experiment which was performed to increase

the tool life by using a smart workpiece holder. In this, the cutting force was

monitored which reduce the metal removal rate. This was conducted on mild

steel & Aluminium work pieces. After using this smart work piece holder there

was 30% increase in tool life & 50% prediction of tool breakage possibilities.

8

Tansel et al. , concluded that tool breakage & wear were determined by the use

of new methods namely Acoustic Emission signals, ART2 & AIM polynomial

network. In Acoustic emission signal method we interpret the digitalised

envelope of AE signals which were produced by analog circuit, we obtain a

final output signal after filtering the signal with a very narrow band pass filter.

The analog processing circuit also filtered the external noise & other

interferences.

To determine the wear the processed AE signals were encoded by using three

main parameters such as ART2 unsupervised neutral network & AIM

polynomial network.

Thepsonthi et al. ,stated in this experiment a simulation of real experiment was

conducted using a software to compare the values obtained with the ideal

values. The main parameters of consideration were cutting temperature, 3D

cutting forces & chip formation. 3D FE Models were used to find out the effect

of tool wear. The conclusion drawn were with the increase in negative rake

angle the tool wear increased.

Mijušković et al. ,stated in this experiment analytical & regression model was

developed for the analysis of tool deflection in micro milling of graphite

electrodes. From the above process depth of cut, width of cut & feed are the

important factor determining the tool deflection. It was observed that angle of

approach is directly proportional to maximum chip thickness.

9

Problem Identification

• Lack in surface finish of Milled specimen

The conventional Milling process did not give us satisfactory outcome in terms

of surface finish. Surface roughness is broadly understood as a measurement of

by how much amplitude the surface departs from a mean and at what frequency

those departures are prone to occur. As per the previous experiments, the factors

that effect the surface finish was the lack of information about parameters such

as Force.

• Lack of required accuracy

While there are few significant disadvantages to the milling process, those that

are present can often be attributed to inaccuracies in a features dimensions.

Lack of accuracy leads to the wastage of raw material & time. This increases

the overall cost of the final output.

• Wearing of tool

The tool gets blunt and its life gets reduced after certain period of usage. This

was a major problem which effected the efficiency of tool. The increase in

temperature is the main cause of tool wearing which is directly proportional to

the force & friction between the tool & the job surface. The lack of feedback

parameter such as force was a major drawback in getting rid of this major

problem which at the end effects the final output.

• Lack of complete information from current feedback system

The current feedback system gives information only about position & velocity

lacking other parameters such as force etc. The lack of these information leads

to lack in surface finish & accuracy.

10

Experimental Setup

1. SinuTrain Software

The methodology which we have chosen is briefed as following. We will be

gaining knowledge about the working of Computer Numerically Controlled

(CNC) Machine by the use of simulation software called as SinuTrain.

SinuTrain/JobShop is the automation system simulation CNC training software

on CD-ROM. It runs on a PC and is as suitable for training purposes and self-

study as it is for writing programs and simulation.

SinuTrain incorporates the functionality of the HMI Advanced operator

interface of the SINUMERIK 810D/840D and 840Di controls and is capable of

running on a standard PC under Windows OS. The software is supplemented by

services that are required to set up and operate a training centre. This modular

system as a whole represents a holistic approach to meeting the needs of those

involved in teaching and studying Computer Numerically Controlled

technology.

Figure 1 - SinuTrain Software

11

By using the SinuTrain software we have got a keen insight about the working

Computer Numerically Controlled (CNC) Machine in a virtual platform. We

will do some experiments regarding process like milling and then moving to

micro milling process which will be useful in attaining micro features.

The experiments will be conducted to improve the surface finish & reduce tool

wear by changing

1. Tool speed

2. Feed Rate

3. Clear the chips

Snapshot of GUI in CNC Machine

12

2. Cutting Tool

An end mill is a type of milling cutter, a cutting tool used in industrial milling

applications. It is distinguished from the drill bit in its application, geometry,

and manufacture. While a drill bit can only cut in the axial direction, a milling

bit can generally cut in all directions, though some cannot cut axially. End mills

(middle row in image) are those tools which have cutting teeth at one end, as

well as on the sides. The word end mill is generally used to refer to flat

bottomed cutters, but also include rounded cutters (referred to as ball nosed) and

radiused cutters (referred to as bull nose, or torus). They are usually made from

high speed steel or cemented carbide, and have one or more flutes. They are the

most common tool used in a vertical mill.

Snapshot of End Mill Cutting Tool

13

The specification & image of the cutting tool used in the experiment is shown

below -

Diameter & Weight of the Cutting Tools

14

3. Sensors

A sensor is an object whose purpose is to detect events or changes in its

environment, and then provide a corresponding output. A sensor is a type of

transducer; sensors may provide various types of output, but typically use

electrical or optical signals. For example, a thermocouple generates a known

voltage (the output) in response to its temperature (the environment). A

mercury-in-glass thermometer, similarly, converts measured temperature into

expansion and contraction of a liquid, which can be read on a calibrated glass

tube.

Sensors (NICTECH – CF – 120 – 2AA – (II) – C20 , 2mm , 120 ohm)

15

4. Data Acquisition System

Data acquisition (DAQ) is the process of measuring an electrical or physical

phenomenon such as voltage, current, temperature, pressure, or sound with a

computer. A DAQ system consists of sensors, DAQ measurement hardware,

and a computer with programmable software. Compared to traditional

measurement systems, PC-based DAQ systems exploit the processing power,

productivity, display, and connectivity capabilities of industry-standard

computers providing a more powerful, flexible, and cost-effective measurement

solution.

DAQ System (NI ELVIS II)

16

5. Tool Vice

It is a mechanical apparatus used to secure an object to allow work to be

performed on it. Vices have two parallel jaws, one fixed and the other movable,

threaded in and out by a screw and lever.

Vice device consisting of two parallel jaws for holding a workpiece; one of the

jaws is fixed and the other movable by a screw, a lever, or a cam. When used

for holding a workpiece during hand operations, such as filing, hammering, or

sawing, the vise may be permanently bolted to a bench. In vises designed to

hold metallic workpieces, the active faces of the jaws are hardened steel plates,

often removable, with serrations that grip the workpiece; to prevent damage to

soft parts, the permanent jaws can be covered with temporary jaws made from

sheet copper or leather. Pipe vises have double V-shaped jaws that grip in four

places instead of only two. Woodworking vises have smooth jaws, often of

wood, and rely on friction alone rather than on serrations.

For holding workpieces on the tables of machine tools, vises with smooth

hardened-steel jaws and flat bases are used. These machine vises are portable

but may be clamped to the machine table when in use; means may also be

provided for swivelling the active part of the vise so that the workpiece can be

held in a variety of positions relative to the base. For holding parts that cannot

be clamped with flat jaws, special jaws can be provided.

Vice

17

6. Computer Numerically Controlled (CNC)

Numerical control (NC) is the automation of machine tools that are operated by

precisely programmed commands encoded on a storage medium, as opposed to

controlled manually by hand wheels or levers, or mechanically automated by

cams alone. Most NC today is computer (or computerized) numerical control

(CNC), in which computers play an integral part of the control.

In modern CNC systems, end-to-end component design is highly automated

using computer-aided design (CAD) and computer-aided manufacturing (CAM)

programs. The programs produce a computer file that is interpreted to extract

the commands needed to operate a particular machine by use of a post

processor, and then loaded into the CNC machines for production. Since any

particular component might require the use of a number of different tools –

drills, saws, etc., modern machines often combine multiple tools into a single

"cell". In other installations, a number of different machines are used with an

external controller and human or robotic operators that move the component

from machine to machine. In either case, the series of steps needed to produce

any part is highly automated and produces a part that closely matches the

original CAD design.

MTAB Milling CNC Machine

18

6. Wheatstone Bridge

A Wheatstone bridge is an electrical circuit used to measure an unknown

electrical resistance by balancing two legs of a bridge circuit, one leg of which

includes the unknown component. The primary benefit of a wheatstone bridge is

its ability to provide extremely accurate measurements (in contrast with

something like a simple voltage divider). Its operation is similar to the original

potentiometer.

The Wheatstone bridge was invented by Samuel Hunter Christie in 1833 and

improved and popularized by Sir Charles Wheatstone in 1843. One of the

Wheatstone bridge's initial uses was for the purpose of soils analysis and

comparison.

Wheatstone Bridge

19

Experimental Process

The main aim of our project is to improve the feedback system of CNC machine

by associating DAQ system. The steps taken during the experiment are:

1. Software Simulation.

2. Selection of Specimen & its material.

3. Pre Experimental Setup of Sensors, Wheatstone Bridge & Tool.

4. CNC Coding.

5. Associating DAQ System.

1. Software Simulation

Before trying our hands on real CNC Machine, we made our hands free by

doing simulation in software called ‘SinuTrain’. This helped us in getting a

brief idea about the working of CNC Machine in the virtual world. It was

helpful in getting a grip over the CNC’s GUI (Graphical User Interface)

software.

2. Selection of Specimen & its material

Since copper has a good machinable properties, we have selected it as our job

for performing micro milling. Copper is a soft, malleable and ductile metal with

very high thermal and electrical conductivity. It has Young’s Modulus of 110-

128 Gpa & Brinell Hardness of 235-878 Mpa.

Copper & Aluminium Specimens

20

3. Pre Experimental Setup of Sensors, Wheatstone Bridge & Tool

In this project, the sensor used is NICTECH – CF – 120 – 2AA – (II) – C20

which has 2 mm of length & is of 120 Ohm. This sensor was attached to the

specimen in a specified manner as shown in the figure. There sensors are used

to calculate the force acting on the specimen in that direction.

Sensors attached in Copper Specimen

Tool holder is used to hold the tool in such a way that it doesn’t vibrate during

the milling operation. It gives support to the primary tool & helps in getting a

high quality finished job.

21

In practice, strain measurements rarely involve quantities larger than a few

millistrain (e x 10^-3). Therefore, to measure the strain requires accurate

measurement of very small changes in resistance wheatstone bridge is used. For

example, suppose a test specimen undergoes a strain of 500 me. To measure

such small changes in resistance, strain gages are almost always used in a bridge

configuration with a voltage excitation source. Since the wheatstone bridge is

applicable only for a particular ratios of resistance we have set the resistors to

120 Ohm.

Setting resistance to 120 Ohm in Wheatstone Bridge

4. CNC Programming

CNC part program is a detailed list of instructions that need to be executed by

the Machine Control Unit to achieve the final component shape. The Machining

sequence needed to manufacture a given part is broken down into small

elements and written in a specific format understood by the MCU. Most NC

today is computer (or computerized) numerical control (CNC), in which

computers play an integral part of the control. In modern CNC systems, end-to-

end component design is highly automated using computer-aided design (CAD)

and computer-aided manufacturing (CAM) programs. G-code is a language in

which people tell computerized machine tools how to make something. The

"how" is defined by instructions on where to move, how fast to move, and what

path to move.

22

CNC Program

CNC Program:

G71G94F10

G75Z0

G75X0Y0

M06T01D1

M03S3000

G0G90G54X0Y0

G0Z10

G01Z-0.05

G01X0Y2

G01X2Y2

G01X2Y0

G01X0Y0

G01Z0

G0G90Z50

G75Z0M05

G75X0Y0

M30

23

5. Association of DAQ System to CNC

Data acquisition is the process of sampling signals that measure real world

physical conditions and converting the resulting samples into digital numeric

values that can be manipulated by a computer. In our project, DAQ system has

helped us in converting the voltage fluctuations to force parameters. LabView is

a software which shows the final output in the form of graphs.

DAQ System associated with CNC

24

Experimental Setup

1• Software Simulation

2• Selection of Specimen & its

material

3• Pre Experimental Setup of Sensors,

Wheatstone Bridge & Tool.

4• CNC Coding

5• Association of DAQ System

6• Working on Specimen

7• Procurement of Graphs

25

Experimental Outcome

The main aim of our project was to obtain an extra parameter such as Force by

the use of DAQ system associated with CNC Machine. By obtaining the Force

parameter we could optimise the cost, resources & time. The following are the

graphs between Force & Time in the direction X & Z.

26

27

Conclusion

1. From this activity, we have learned how to organize the CNC Machine

(Micro Milling) and understand the operation involved.

2. Besides that, we also know the purpose of the main parts of this machine.

3. We have used the Data Acquisition System in CNC Machine for obtaining

the required parameters at a great degree of accuracy & precision.

4. An extra feedback parameter (Force) is obtained which can be used to

optimise the micro milling process. This has helped us in saving the time &

material by making changes in parameters which is affecting it.

28

References

1. M Rahman, A Senthil Kumar, J.R.S Prakash : Micro milling of pure copper.

2. Young-bong Bang , Kyung-min Lee, Seungryul Oh : 5-axis micro milling

machine for machining micro parts.

3. I. Tansel , O. Rodriguez, M. Trujillo, E. Paz, W. Li : Micro-end-milling—I.

Wear and breakage.

4. J. Chae, S.S. Park, T. Freiheit : Investigation of micro-cutting operations.

5. I. Tansel , A. Nedbouyan, M. Trujillo, B. Tansel : Micro-end-milling—II.

Extending tool life with a Smart Workpiece Holder (SWH).

6. I. Tansel , M. Trujillo, A. Nedbouyan, C. Velez, Wei-Yu Bao, T.T. Arkan,

B. Tansel : Micro-end-milling—III. Wear estimation and tool breakage

detection using acoustic emission signals.

7. Goran Mijušković, Peter Krajnik & Janez Kopač : Analysis of tool deflection

in micro milling of graphite electrodes.

8. Elisa Vázquez & Jéssica Gomar & Joaquim Ciurana & Ciro A.

Rodríguez : Evaluation of machine-tool motion accuracy using a CNC

machining center in micro-milling processes.