45203729 Lathe Machine

STUDY OF CRYOGENIC MACHINING FOR SINGLE TIP CUTTING TOOL

USING NEW COOLING SYSTEM DESIGN

HAZWAN AIZAT BIN MOHAMED HUSSIN

A report submitted in partial fulfillment of the requirements

For the award of the degree of

Bachelor of Mechanical Engineering with Manufacturing

Faculty of Mechanical Engineering

UNIVERSITI MALAYSIA PAHANG

NOVEMBER 2008

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SUPERVISOR’S DECLARATION

We hereby declare that we have checked this project and in our opinion this project is

satisfactory in terms of scope and quality for the award of the degree of Bachelor of

Mechanical Engineering with Manufacturing.

Signature : ………………………….

Name of Supervisor : En. Zamzuri Bin Hamedon

Date : November 2008

Signature : …………………………….

Name of Panel :

Date : November 2008

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STUDENT’S DECLARATION

I declare that this final year project report entitled “Study of Cryogenic Machining for

Single Tip Cutting Tool Using New Cooling System Design” is the result of my own

research except as cited in the references. The report has not been accepted for any

degree and is not concurrently submitted in candidature of any other degree.

Signature : ………………………………

Name of Candidate : Hazwan Aizat Bin Mohamed Hussin

Date : November 2008

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Dedicated to my dearest parent.

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ACKNOWLEDGEMENT

First of all, thanks you the Almighty god, Allah S.W.T for blessing me finish this

project successfully. Special gratitude express to my supervisor En. Zamzuri Bin

Hamedon for his brilliant idea, invaluable guidance, continuously encouragement and

constant support in making this project possible. His knowledge, experiences and

technical skills always impress me and open my minds to always think differently than

what written in text books or lectures to solve any technical problems.

Besides that, my sincere thanks to my lab mates who teach me a lot to handle

machines that I was going to use. Not forget also to Mechanical Lab staffs that done

really good jobs monitoring and assisting in technical support during the fabrications.

I would like to thanks also to my beloved parent for their dreams and faith in me.

Their pray will always follow and help me whenever I goes. Lastly, to all university staff

from Mechanical Engineering Faculty, my fellow friends and who was helping

indirectly, thanks for giving me such a sincere support and assistance.

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ABSTRACT

This project deals with a cryogenic cooling approach for a lathe machine. In steel

machining, high cutting temperature will result reduce in cutting tool life and also

reduce the product machined quality. Nowadays, conventional cutting fluid used to

control the high cutting temperature but it still ineffective. Soluble oil is the favorable

conventional cutting fluid used. Unfortunately, it leads to environment pollution

problem especially when its dispose to the earth. Cryogenic cooling which is an

environmental friendly cutting fluid or called as coolant can help rids of conventional

cutting fluid pollution problem and ineffective controlling cutting temperature. Present

works are design and fabricate cryogenic coolant system that suit with a conventional

lathe machine. Three cylindrical AISI 1045 steel tested with TNMG TT5100 which is a

Chemical Vapor Deposition (CVD) coated cutting tool insert. The result compared with

dry machining, machining with soluble oil as coolant and cryogenic machining which

use nitrogen gas as the coolant. Results indicate the benefit of cryogenic cooling in

cutting tool life and workpiece surface finish. This may attributed by the reduction of

cutting zone temperature. Further more, from the result proves that soluble oil failed to

improve cutting tool life and product surface finish.

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ABSTRAK

Projek ini melibatkan cara penyejukan secara kriogen untuk sebuah mesin larik. Dalam

memesin besi, suhu pemotongan yang tinggi akan menyebabkan pengurangan jangka

hayat bagi alat pemotong dan mengurangkan kualiti produk yang dimesin. Kini, cecair

pemotong biasa digunakan untuk mengawal suhu pemotongan yang tinggi tetapi ia

masih tidak efektif. Minyak terlarut ialah cecair pemotong biasa yang paling digemari

digunakan. Akan tetapi, ia menyebabkan masalah pencemaran alam terutama sekali

apabila dibuang ke bumi. Penyejukan secara kriogen iaitu sejenis cecair pemotong yang

mesra alam atau dipanggil sebagai cecair penyejuk boleh membantu menyelesaikan

masalah pencemaran cecair pemotong biasa dan kawalan suhu memotong yang tidak

efektif. Tugasan ini ialah mereka bentuk dan membina sistem cecair penyejuk kriogen

yang sesuai dengan mesin larik biasa. Tiga silinder AISI 1045 besi dicuba dengan

TNMG TT5100 iaitu mata pemotong jenis selaputan Pemendapan Wap Kimia (CVD).

Keputusan dibandingkan antara memesin secara kering, memesin dengan minyak

terlarut sebagai cecair penyejuk dan memesin secara kriogen yang menggunakan gas

nitrogen sebagai cecair penyejuknya. Keputusan menunjukkan kelebihan penyejukan

kriogen dalam jangka hayat alat pemotong dan permukaan benda kerja. Ini mungkin

disebabkan oleh pengurangan suhu zon pemotongan. Tambahan pula, daripada

keputusan membuktikan bahawa minyak terlarut gagal untuk memperbaiki jangka hayat

alat pemotong dan permukaan produk.

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TABLE OF CONTENTS

PageSUPERVISOR’S DECLARATION iiSTUDENT’S DECLARATION iiiDEDICATION ivACKNOWLEDGEMENTS vABSTRACT viABSTRAK viiTABLE OF CONTENTS viiiLIST OF TABLES xLIST OF FIGURES xiLIST OF SYMBOLS xiiiLIST OF ABBREVIATIONS xiv

CHAPTER 1 INTRODUCTION

1.1 Introduction 11.2 Project Background 11.3 Problem Statement 21.4 Project Objectives 21.5 Project Scopes 3

CHAPTER 2 LITERATURE REVIEW

2.1 Introduction 42.2 Lathe Machine

2.2.1 Introduction 42.2.2 Machine Components and Features 52.2.3 Cutting Tool Types and Operations 82.2.4 Cutting Parameters 92.2.5 Safety Consideration for Lathe Machine 13

2.3 Coolant/Cutting Fluid2.3.1 Introduction 142.3.2 Coolant Purposes 142.3.3 Coolant Applied Method 152.3.4 Cryogenic Coolant 162.3.5 Safety Considerations for Cryogenic Coolant 18

2.4 Nozzle2.4.1 Introduction 19

2.4.2Comparison of Using Nozzle and Tool Holder to Transmit Coolant

20

2.5 Conclusion 21

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CHAPTER 3 METHODOLOGY

3.1 Introduction 223.2 Overview of the Methodology 223.3 Designing

3.3.1 Nozzle 243.3.2 Nozzle Holder 263.3.3 Hose Arrangement 27

3.4 Fabrication3.4.1 Fabrication of Nozzle 283.4.2 Fabrication of Nozzle Holder Long Rod Part 303.4.3 Fabrication of Nozzle Holder Clamping Part 323.4.4 Fabrication of Nozzle Holder Hose Holder Part 34

3.5 Testing3.5.1 Testing Parameters 373.5.2 Workpiece Preparation 38

3.6 Analysis3.6.1 Analysis of Surface Roughness 423.6.2 Analysis of Cutting Tool Wear 43

3.7 Conclusion 43

CHAPTER 4 RESULTS AND DISCUSSIONS

4.1 Results4.1.1 Tool Wear 444.1.2 Surface Roughness 46

4.2 Discussions4.2.1 Tool Wear 494.2.2 Surface Roughness 50

CHAPTER 5 CONCLUSION AND RECOMMENDATION

5.1 Conclusion 515.2 Recommendation 53

REFERENCES 54APPENDICESA Project flow chart 55B Project Gantt chart 58C Lathe machining environments/cooling apply method 61D Detail drawing 63E Exploded View 68

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LIST OF TABLES

Table No. Page

1 Characteristic temperatures of cryogenic fluid. 17

2 Properties of helium and nitrogen. 18

3 Testing parameters. 38

4 Workpiece surface roughness for three different machined environments. 48

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LIST OF FIGURES

Figure No. Page

1 Lathe machine. 5

2 Headstock. 5

3 Carriage. 6

4 Tailstock. 7

5 Standard cutting tool. 8

6 Insert cutting tool. 8

7 Typical straight turning. 10

8 Workpiece depth of cut (DOC) determines. 12

9 Workpiece surface roughness determines. 13

10 Temperature distribution at the cutting zone. 15

11 Coolant transmitted by nozzle. 21

12 Coolant transmitted by modified tool holder. 21

13 Cryogenic cooling system setup. 23

14 Nozzle direction. 25

15 Nozzle side view. 25

16 Nozzle holder design. 26

17 Lathe machine carriage track. 26

18 Nozzle old design. 36

19 Nozzle new design 37

20 Workpiece dimension. 38

21 Cutting tool movement. 39

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22 Testing with dry machining environment. 40

23 Testing with wet machining environment. 41

24 Testing with cryogenic machining environment. 41

25 Perthometer. 42

26 IM7000 Series Image Analyzer. 43

27 Tool insert crater wear for dry machining. 45

28 Tool insert crater wear for wet machining. 45

29 Tool insert crater wear for cryogenic machining. 46

30 Printed surface roughness graph from perthometer for dry machining. 47

31 Printed surface roughness graph from perthometer for wet machining. 47

32 Printed surface roughness graph from perthometer for cryogenic machining. 48

33 Comparison of average surface roughness. 49

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LIST OF SYMBOLS

N Spindle speed

Cs Cutting speed

D Workpiece diameter

π Pi (3.142)

µ Micro (×10-6)

Ra Average surface roughness

× Multiply

in Inch

LN2 Liquid nitrogen

N2 Nitrogen gas

mm Millimeter

rev Revolution

Ø Diameter

Lt Travel length

m Meter

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LIST OF ABBREVIATIONS

IPM Inch per minute

IPR Inches per revolution

DOC Depth of cut

RMS Root mean square

EDM Electro discharge machine

AISI American Iron and Steel Institute

rpm Revolution per minute

CVD Chemical vapor deposition

DRO Digital read out

CHAPTER 1

INTRODUCTION

1.1 INTRODUCTION

Cryogenic becomes one of the most suitable coolants (cutting fluid) to replace

the flood type coolants that already available at almost conventional lathe machine

nowadays. Most of CNC lathe machine equipped with soluble oil which is a type of

flood coolant. From the research that already done by researcher such as Mirghani I.

Ahmed, Yakup Yildiz, etc., cryogenic will enhance lathe machine cutting tool life better

than what a flood coolant can do. Cost and set up time can be reduce because cutting

tool is the critical part of lathe machine that always breaks. The objectives of this project

is to equip a conventional lathe machine with a cryogenic coolant system by fabricate it

from the cryogenic dewar/cylinder to the nozzle. Three different machining

environments will be done to compare the chips produced as the evidence of goodness

of cryogenic coolant.

1.2 PROJECT BACKGROUND

Lathe machine is the most common machine in a manufacturing plant. Usually, a

small plant used conventional lathe machines in their metal cutting process. The

conventional machine needs good skills operator to handle it so that the metal that been

cut will result fine finish surface. Even a good skills operator handle it, machine

breakdown still might be happen. The critical part that usually breaks at the machine is

the cutting tool. Higher feed rate and excessive forces applied are some of the causes

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that contribute cutting tool to break. A flood type coolant system already installed with a

conventional machine when brought from its factory. The coolant gives a little help to

decrease the percentage for the cutting tool to break. So, a type of mist coolant system

would necessary considered as the replacement for the flood type coolant system

because of its ability to enhance cutting tool life better.

1.3 PROBLEM STATEMENTS

The general purpose for any project is to find solutions on a certain problems.

It’s also gives main idea how the project to be completed. For this project, the problems

that need to be solved are:-

1) Any manufacturer wants to reduce cost and time taken to complete a product but

gives better quality products and increases the outputs.

2) Manufacturer tends to upgrade their machines to compete with the new machine

with new technology.

3) Lathe machine cutting tool can easily break and needs to enhance its tool life.

1.4 PROJECT OBJECTIVES

Every works must come out with its own objectives so that its will achieves the

goal successfully. For this project, the objectives are:-

1) To design a cooling system for a lathe machine.

2) To fabricate the cooling system that use cryogenic as the coolant.

3) To test the lathe machine operates with its newly installed coolant system.

4) To analyze the cutting tool wear and workpiece surface roughness.

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1.5 PROJECT SCOPES

The general scopes for this project are:-

1) Do the literature reviews on lathe machine, coolant or cutting fluid and nozzle.

2) Choose the cryogenic coolant type for the project study. Interest in nitrogen gas

(N2) for the cryogenic coolant.

3) Develop Gantt chart and flow chart for this project.

4) Design the coolant nozzle by using SolidWork software.

5) Nozzle holder designed by using SolidWork software.

6) Coolant hose arrangement designed to the coolant system.

7) Fabricate designed coolant nozzle by using lathe machine and drilling machine.

8) Fabricate nozzle holder by using milling machine.

9) Test the coolant system with three different machining environments.

CHAPTER 2

LITERATURE REVIEW

2.1 INTRODUCTION

Coolant or cutting fluid widely used in metal machining operations such as for

drilling machine, lathe machine and milling machine. The purposes of coolant are to

wash away chips from the tool, reduce heat generated, reduces frictions between tool

and workpiece and also to enhance tools life. Most of the CNC machines are already

installed with a coolant system by the manufactured factory itself. For this project, a

lathe will be installed with a coolant system that use cryogenic as the coolant which is a

mist coolant type. The common lathe machine used fluid as its coolant. A nozzle used to

transmit cryogenic from its tank to the tool or workpiece at the lathe machine.

2.2 LATHE MACHINE

2.2.1 Introduction

Lathe machine (Figure 1) is a metal removal machine that used for shaping

metals and sometimes wood or other materials by held the workpiece and rotated its

while the cutting tool advanced to the workpiece and causing the cutting action. The

basic lathe machine was designed to cut cylindrical workpiece shape, but now its has

been developed further and can produce screw, threads, tapered work, drilled holes,

knurled surfaces and crankshafts. The typical lathe machine provides with variety of

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rotating speeds and can manually or automatically move the cutting tool towards the

workpiece.

Figure 1: Lathe machine (Wikipedia.com)

2.2.2 Machine Components and Features

Lathe machine consists of four basic or main parts which are headstock

(Figure 2), carriage (Figure 3) and tailstock (Figure 4). Every main part also consists of

other parts which is very important to every machinist to know before using the

machine. Other components that are not stated before are bed, cooling pump and brake.

Bed connects the headstock with carriage and tailstock. Bed also acts as a rail for

carriage and tailstock to travel. Cooling pump supplies cooling fluids via a hose towards

a desires direction. Brake which is located below the bed used when there is an

emergency happen and needs to stop the spindle immediately.

Headstock

Figure 2: Headstock (Wikipedia.com)

(H1) Gear headstock housing – House the spindle, speed change mechanism and change

gears.

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(H2) Intermediate gear lever – Controls the rotational speed.

(H3) High low gear level – Controls the rotational speed.

(H4) Spindle – Holds and drives workpiece.

(H5) Tumbler gears – Enables a gear train of the correct ratio and direction.

(H6) Quick change gear box with 4 selectors (3 levers) – Change gears.

(H7) Lead screw – Transmits power from the headstock to the carriage for screw thread

cutting operations.

(H8) Feed screw – Transmits power from the headstock to the carriage for feeding

operations.

(H9) Forward-reverse switch – Control the forward and reverse carriage mechanism.

(H10) Change gear cover – House the change gears.

Carriage

Figure 3: Carriage (Wikipedia.com)

(1) Toolpost – Mounted the tool bit.

(2) Top-slide – Mounted toolpost and provide small movement along Z-axis.

(2a) Top-slide feedscrew and dial – Move the top-slide to assist in making reproducible

cuts.

(2b) Protractor – Guide top-slide if an angle needed for cutting.

(3) Cross-slide – Used for manual positioning along X-axis.

(3a) Cross-slide Digital Read Out (DRO) scale – Gives operator the exact coordinates of

the tool with respect to workpiece.

(3b) Cross-slide feedscrew and dial – Move the cross-slide to assist in making

reproducible cuts.

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(4) Saddle – Mounted cross-slide.

(5) Apron – Lube oil reservoir that lubricates the apron gears.

(5a) Carriage handwheel – Move the carriage along the bed.

(5b) Half-nut lever – Engages the carriage directly to the lead screw and used only for

threading. Only engage when the feed is set in the neutral position.

(5c) Feed lever – Controls the automatic movement of the Z and X axes.

Tailstock

Figure 4: Tailstock (Wikipedia.com)

(T1) Feed screw – Move the spindle longitudinally.

(T2) Reduction gear box (optional) – Only found in larger center lathes where large

drills may necessitate the extra leverage.

(T3) Body – Contain the extent of spindle and as the housing for other tailstock

components.

(T4) Adjustable base – Provision to offset the tailstock.

(T5) Spindle – Does not rotate. Include a taper to hold drill bits, centers and other

tooling.

(T6) Locking lever – Clamps the tailstock at a fix position.

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2.2.3 Cutting Tool Types and Operations

There are two types of cutting tool which are the standard cutting tool (Figure 5)

type and insert cutting tool (Figure 6) type which is the insert comes out with different

shapes depends on the operation. The cutting tool will be hold by tool holder located at

toolpost at carriage. For lathe machine, the tool is moving with the direction set up by

the carriage towards the rotating workpiece. Cutting fluid or coolant needed in cutting

operation, so that it will enhance tool life and gives better workpiece surface finish. Tool

can easily break if there is no coolant exists especially when high feed rate applied.

Figure 5: Standard cutting tool [1]

Figure 6: Insert cutting tool [2]

There are also lot of operations can be held at the lathe machine. Each operation

used different type of tools. Turning, facing, parting, drilling, boring and thread turning

are the operations that can be held by lathe machine.

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Turning

Turning operations is for reducing the workpiece diameter to a desired dimension.

Roughing tool used for roughly cut the workpiece into a diameter and then, finishing

tool will improve the workpiece surface.

Facing

Lathe machine used a facing tool when want to create a smooth flat face very accurately

perpendicular to cylindrical workpiece axis. If a finer finish is required, repeat the facing

operation final cut used the power feed.

Drilling

Lathe machine can drill a hole accurately concentric with centerline of cylindrical

workpiece. A drill chuck is installed at the tailstock by withdraw the jaws of chuck and

tap drill chuck in place with soft hammer.

Boring

Boring is an operation to enlarge a hole with a single point cutting. A boring bar is used

to support the cutting tool as it extends into the hole. Lower spindle speed required

during this operation because the tool is supported less rigidly.

Thread Turning

A special cutting tool used typically with a 60 degree nose angle. To form threads with a

specified number of threads per inch, the spindle is mechanically coupled to the carriage

lead screw.

2.2.4 Cutting Parameters

When metal is cut, the workpiece surface is driven with respect to the tool, or the

tool with respect to surface, at a relatively high rate of speed. This is called cutting speed

(Cs). Mostly the tool or workpiece revolves. Almost all such machine tools are calibrated

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in revolutions per minute (rpm). The cutting speed is related to the rpm and thus is

conveniently expressed in meter per minute (m/min).

Spindle speed (rpm) is the rotational frequency of lathe machine spindle and its

determined based on the type of material to be cut. Soft steel such as aluminium alloy is

suitable with high spindle speed during machining. If hard steel such as bronze applied

excessive spindle speed, it will cause premature tool wear, breakage, and can cause tool

chatter. Using the correct spindle speed for the material and tools will affect tool life and

the quality of the surface finish. For a straight turning operation, the spindle speed is

determined from the relationship of

where

N = Spindle speed (rpm)

Cs = Cutting speed (m/min)

D = Workpiece diameter (mm)

Figure 7: Typical straight turning (CustomPartNet.com).

(Eq. 1)