An Evaluation of the Characteristics of Metal Cutting Fluid Due to

the Metal Chips Contamination

by

Idreyanna Binti Idrus

This report is submitted in partial fulfillment of the requirement for

the degree of Bachelor of Engineering (Hons. ) Civil Engineering

from the Faculty of Engineering llniversiti Malaysia Sarawak

2002

Thank you Allah ... for giving me strength to finish this project

ACKNOWLEDGEMENT

I would like to express my gratitude and appreciation to my Project Supervisor, Dr.

Law Puong Ling for his helpful guidance and encouragement throughout the duration

of the project.

I would also like to thank to my colleagues especially, Jessica ,

Azreenawatty,

Hallimaton ,

Sophia , Azlina

, Salmiah and Rudy for their help and giving the

valuable ideas and encouragement. In addition, I would like to express my special and

warmest to my parent, Encik Idrus B. Jasni and Puan Latifah Bt. Sulaiman for their

support that gave me the strength and courage during my difficult times. Thank you .

May Allah bless all of you.

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TABLES OF CONTENTS

CONTENT

ACKNOWLEDGMENT

TABLES OF CONTENTS

LIST OF TABLES

LIST OF FIGURES

ABSTRACT

ABSTRAK

CHAPTER 1: INTRODUCTION

1.1 General Introduction

1.2 Background

1.3 Objectives

CHATER 2: LITERATURE REVIEW

2.1 Introduction

2.2 Definition of Metal Cutting Fluid

2.3 Characteristics of Metal Cutting Fluid

2.3.1 Coolants for Metal Cutting

2.3.2 Lubrication

2.3.2.1 Reduce Friction

PAGE

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ý ý

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IV

2.3.2.2 Reduce Wear 11

2.3.2.3 Wash the Chips Away From the Cutting Region 11

2.3.2.4 Prevent Corrosion 12

2.4 Category of Metal Cutting Fluid 12

2.4.1 Straight Oils 12

2.4.2 Chemically Treated Oils 13

2.4.2.1 Sulfurized mineral oils 13

2.4.2.2 Sulfurized and chlorinated 13

mineral oils

2.4.2.3 Fatty oil blends 14

2.4.3 Soluble Oils 15

2.4.4 Chemical cutting fluids 15

2.4 Cutting Fluid for Various Type and Condition 16

2.6 Effects of Metal Cutting Fluid 17

2.6.1 Tool life 17

2.6.2 Cutting tool material 18

2.6.3 Workpiece material 18

2.6.4 Biological and environmental effects. 18

N,

CHAPTER 3: METAL CHIPS CONTAMINATION

3.1 Contamination

3.2 Mechanism of chip formation

3.3 The chip/tool interface

3.4 Tribology

3.4.1 Friction

3.4.2 Wear Debris Analysis

3.4.3 Wear

3.4.3.1 Adhesive wear

3.4.3.2 Abrasive wear

3.4.3.3 Corrosive wear

3.4.3.4 Fatigue Wear

3.5 Relationship between friction and Adhesive Wear

3.6 PH

CHAPTER 4: METHODOLOGY

4.1 Introduction

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4.2 To evaluate the performance of the metal cutting fluid due to metal

chips contamination

4.3 Experimental Design

4.4 Method of Experiment

4.5 Spring Stiffness

4.6 Friction Measurement

4.7 Wear measurement

4.8 pH, odor and temperature

CHAPTER 5: FINDINGS AND DISCUSSION

5.1 General

5.2 Stiffness of the Spring

5.3 Coefficient of friction ,µ

5.4 Amount of Wear

5.5 The amount of wear and coefficient of friction

5.6 pH, odor, and temperature

CHAPTER 6: CONCLUSION AND RECOMMENDATION

6.1 Conclusion

6.2 Recommendation

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BIBLIOGRAPHY 54

APPENDIXES

1. FRICTION

2. LUBRICATING OIL CHARACTERISTICS

3. LUBRICITY TEST

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LIST OF TABLES

TABLES PAGE

2.1 General recommendation for cutting fluids for machining 6

5.1 Spring stiffness ,k 42

5.2 Coefficient of friction 45

5.3 The amount of wear with time 47

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LIST OF FIGURES

FIGURE PAGE

2.1 Metal surfaces greatly magnified under a microscope 10

2.2 Lubrication separates moving parts 11

3.1 Schematic diagram of two -dimensional orthogonal cutting 22

3.2 Chip shapes 23

3.3 Schematic showing two possibilities of break (1 and 2) during

shearing of an interface. 28

3.4 Schematics of (a) a rough , hard surface or a surface mounted 30

with abrasive grits sliding on a softer surface, and (b) free

abrasive grits caught between the surfaces with at least one of

the surfaces softer than the abrasive grits

4.1 Block on ring lubricity test 34

4.2 The experimental design of lubricity ring test 35

4.3 The experiment to determine the spring stiffness 38

5.1 Relation between coefficient of friction and time 49

5.2 Relation between the amount of wear particles and time 50

5.3 Relation between the amount of wear particles and coefficient

of friction 51

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ABSTRAK

Kajian ini membincangkan tentang ciri-ciri "cutting fluid" kesan daripada

"contamination" atau pun sebarang substrat yang tidak diperlukan dalam sesuatu

cecair. Untuk mencapai objektif tersebut, satu eksperimen hendaklah dijalankan. la

melibatkan proses mereka dan mendirikan " simple lubricity test rig". Jumlah partikel

di dalam "cutting fluid" diperolehi dan keputusannya dianalisis. Nilai pemalar geseran

diambil setiap kali sample diambil. Hubungan antara pemalar geseran -masa dan

kandungan partikel asing di dalam " cutting fluid"-masa diperolehi . Dengan itu,

hubungan antara pemalar geseran dan kandunga partikel di dalam " cutting fluid"

dapat diketahui.

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CHAPTER 1

INTRODUCTION

1.1 GENERAL INTRODUCTION

Today, metal cutting is a very large segment indeed in our industry . The motorcar industry,

electrical engineering, railways, shipbuilding, aircraft manufacture, production of domestic

equipment and the machine tool industry itself. Fluids have been important in the industry

as an aid to the process. Water may have been the first fluid, followed by animal fats,

vegetable oils, mineral oil, oil-in water emulsions, and in recent years, by clear synthetic

chemical solutions.

Metal cutting fluids are dynamic systems due to their usage and environment. Because its

characteristics are widely changing during time, the same product may have a different

composition after using in different systems for enough long time periods. Therefore,

cutting fluid maintenance is very important for its proper application in processes. In

addition, keeping the fluid properties between the proposed limits will increase its lifetime.

I

In metal cutting, fluids are used to reduce heat buildup and therefore extend tool life.

Usually, the proper cutting fluids also allow higher cutting speeds and feeds and helps

produce a better finish on the machine part. These cutting fluids perform a very important

role and many operations cannot simply carried out with any type of fluid.

1.2 BACKGROUND

Firms have tended to dispose of their coolants or metal cutting fluids as soon as they

showed signs of fouling decreased efficiency. Much of the time such disposal is not

necessary. A thorough management program can definitely extend the life of metal cutting

fluids and is profitable for the firm. Many of the modern metal cutting fluids and coolants

are designed and formulated to be environmentally safe and biodegradable.

Some of the modern metal cutting fluids are supplied in aerosol cans and are sprayed on the

work piece while the machining operation is being performed. These spray-application

fluids adhere strongly to the work piece and allow easier machinability while preventing

corrosion on the work piece, such as rusting on ferrous materials. Considerations for

choosing a quality coolant and maximizing the life of coolants are important when using

the machine. Thus the aim, to recycle the metal cutting fluids is a subject matter of this

project.

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Metal -cutting fluids (coolants) are contaminated with tramp oils and metal chips with use,

and tramp oil contamination leads to the growth of anaerobic bacteria that shorten coolant

life. The existing metal working fluids recycling or treatment methods are not cost-

effective because they generate huge volumes of waste coolant. The ever increasing

disposal cost has been of great concern among metalworking facilities, and the industry has

been looking for ways to reduce coolant-related costs in their machining operations.

1.3 OBJECTIVES

The objectives of this final year project is to evaluate the performance of metal cutting fluid

due to metal chips contamination in terms of lubricity, pH, odor and temperature.

To obtain these objectives, lab experiment will be carried out properly. It involved the

design and construction of a simple lubricity test rig. The experiment will he explained in

chapter 4. While the pH, odor and temperature were taken in every alternate day over a

period of two weeks.

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CHAPTER 2

LITERATURE REVIEW

2.1 INTRODUCTION

This chapter looks into previous research and analysis that has been done by other

researchers. The main topic that will be stated are the characteristics of metal cutting fluid,

the functions and impacts of cutting fluid.

2.2 DEFINITION OF METAL CUTTING FLUIDS

Metal -Cutting Fluids are engineering materials that optimize the metal cutting process.

The fluids must provide a layer of lubricants to act as a cushion between the work piece

and the tool in order to reduce friction. Cutting fluids are also called coolants and lubricants

. The role of a cutting fluid as a coolant or lubricant is very sensitive to the cutting speed.

Generally, Metal-Cutting Fluids that work hard on the machine and soft on the skin. Metal-

cutting fluids of various compositions have always been used extensively in machining

operations. Most machine shops show that some cutting operations are carried out dry, but

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in many cases, a flood of liquid is directed over the tool, to act as a coolant and/or a

lubricants.

Cutting fluids play a significantly role in machining operations and impact shop

productivity, tool life and quality of work. The primary function of cutting fluid is

temperature control through cooling and lubrication (Aronson, et al., 1994). A fluid's

cooling and lubrication properties are critical in decreasing tool wear and extending tool

life. Cooling and lubrication are also important in achieving the desired size, finish and

shape of the work piece. A secondary function of cutting fluid is to flush away chips and

metal fines from the tool/ work piece interface to prevent a finished surface from becoming

marred and also to reduce the occurrence of built-up edge (BUE).

The chips of some metals have a tendency to temporarily weld onto the top surface of the

toolbit. This built-up edge is an unstable condition since it is continually formed and

released. This is generally undesirable because it result in greater power consumption,

poorer finish, and possible cratering of the toolbit. Although cutting fluids are only remedy

for this problem, they are widely used to reduce friction and heat, which in turn reduces the

formation of a built -up edge on the toolbit

The term coolant was coined by researchers soon after F. W. Taylor reported that tool lite

could be improved by applying water. The term lubricant originated with the introduction

using oils. Combination cutting fluids and coolants are being produced which may be used

for most of the high-speed machining operations afforded by the advanced cutting tool

materials. With the advent of universal-type cutting/coolant combination fluids, the

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inventory of cutting fluids and coolants can be kept to a minimum within a manufacturing

facility or machine shop. The general recommendations for cutting fluids for machining are

stated in the table 2.1

Material Type of fluid

Aluminum D, MO, E, MO +FO, CSN

Beryllium MO, E, CSN

Copper D, E, CSN, MO+FO

Magnesium D, E, CSN, MO+FO

Nickel MO, E, CSN

Refractory MO, E, EP

Steels (Carbon and low alloy) D, MO, E, CSN

Titanium CSN, EP, MO

Zinc D, MO, E, CSN

Zirconium D, E, CSN

Table 2.1 : General Recommendation for Cutting fluids for Machining

CSN, Chemicals and Synthetics FO, fatty oil

D, Dry

E, Emulsion

EP, Extreme Pressure

MO, Mineral Oil

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2.3 CHARACTERISTICS OF METAL CUTTING FLUID

Cutting fluids has the following six characteristics. It can be divided into two categories

lubricants and coolants. The machinist must understand cutting fluids characteristics and be

able to choose the one best suited to a particular job.

1. Lubrication. The cutting fluid must prevent or reduce formation of built-up edge on

tools or cratering and lubricate some of the working parts on automatic screw

machines and similar tools.

2. Cooling capability. The cutting fluids must be able to reduce the temperature of the

tool and the work piece to extend tool life and allow higher cutting speeds and feeds

rates.

3. Rust and residue prevention. The work piece and the machine must be protected

from rust and the formation of scum

4. Safety. The cutting fluids must be nontoxic and nonflammable under normal

working conditions. It should not cause skin irritation.

S. Stability. The cutting fluid should not support bacterial growth ( become rancid) in

use or in storage , and its characteristics should not change with age.

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6. Compatibility. The cutting fluid must be compatible with other lubricants used on

the machine.

2.3.1 Coolants for Metal Cutting

The metal cutting process creates much heat and friction. If the heat and friction are

not reduced, the tools used in the process are quickly damaged and destroyed. Also,

the quality of the product made is diminished because of inefficient tools and

damage to the product while it is being manufactured.

In order to increase metal removal rates, feeds and speeds must be increased. These

increases cause elevated temperature which is the most critical limitation to tool life.

The cutting fluid will carry the heat away and as the result the temperature will be

decreased. Coolants reduce friction at the tool / substrate interface and transfer heat

away from the tools and the material being processed, reducing the time to process

the metal, increasing the quality of the workmanship, and increasing tool life. The

ability to transfer the heat away from the metal cutting process is why metal cutting

fluids are often called coolants.

Almost all the work that goes into machining is dissipated as heat of deformation in

75% while 25% is due to the friction. About 80% of the total heat produced goes

into chip, 10% into tool and another 10% into work piece.

2.3.2 Lubrication

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The term lubrication in relation to cutting fluids is used to describe action by the

fluid at the interface which reduces the tool forces and amount of heat generated.

Cutting fluids that acts as a lubricant will reduce the coefficient of friction between

the cutting tool and the chip, and between the cutting tool and the work piece.

A major objective of the use of lubricants is to improve the life of cutting tools but

under some circumstances they cause an increase in the rate of wear. By reducing

friction and wear , tool life and surface finish are improved. Improved surface

finish is accomplished by restraining the formation of a built-up edge (BUE) on the

cutting tool. A lubricant reduces the BUE by producing a thinner, less deformed,

and cooler chip.

Improved surface finish is a major objective of cutting lubricants. In this respect

they are particularly effective at rather low cutting speeds and feed rates in the

presence of a built-up edge.

A lubricant perform 6 basic functions as stated below :

(i) Reduce friction

(ii) Reduce Wear

(iii) Absorb shock

(iv) Reduce temperature

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(v) Minimize corrosion

Seal out contaminants

2.3.2.1 Reduce Friction

Primary function of a lubricant. It does this by separating the two contact

surfaces and allowing them to move over one another . Figure 2.1 shows an

elevation cross section of how the two surfaces would appear if greatly

magnified.

Figure 2.1 Metal surfaces greatly magnified under a

microscope with no lubrication.

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Figure2.2 Lubrication separates moving parts.

2.3.2.2 Reduce Wear

With lubricant, the wear element particulates are significantly reduced and

component life is extended.

2.4 WASH THE CHIP AWAY FROM THE CUTTING REGION

The cutting fluids helps remov ing chips from the hole as the coolants flows out

through the flutes of the drill. Thus it will prevent metal pick-up on the both the tool

and the work piece by flushing away the chips as they are produced. The surface

finish of the work piece will be improved.

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2.4.1 Prevent Corrosion

Corrosion of a metal is the deterioration of a material because of a reaction with its

environment. Some coolant has additives to prevent and cure problems regarding

corrosion. It will provide a protective coating. Antioxidants additive prevent oxygen

from attacking the fluid.

2.5 CATEGORY OF METAL CUTTING FLUID

There are four major categories of cutting fluids : straight oils, chemically treated

oils, soluble oils, and chemically -water compounds.

2.5.1 Straight Oils

Straight mineral oils are used extensively in machining nonferrous metals and

free -machining steels. They are not chemically active and do not stain the

machined parts. Straight mineral oils have relatively good lubricating

qualities, but they are not very effective coolants. They are very stable

cutting fluids and can be reused many times if properly cleaned and filtered.

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2.5.2 Chemically Treated Oils

These cutting oils are chemically active at relatively low temperatures(200

to 3000F) and have very good lubricating properties, particularly when

chlorine and sulfur are added.

There are three general categories of chemically treated oils:

2.5.2.1 Sulfurized mineral oils

Sulfurized mineral oils are used almost exclusively with tough low-

carbon and low-alloy steels. The oil becomes chemically active at

relatively low temperatures and stains any copper base alloys. The

sulfur content usually below 1.0 percent in the oil reacts with ferrous

metals when the cutting oil is exposed to the temperatures and

pressures produced by the metal cutting process. An iron sulfide film

that resists high pressures and prevents galling is formed between the

tool and the chip.

2.5.2.2 Sulfurized and chlorinated mineral oils

Sulfurized and chlorinated mineral oils are recommended for cutting

tough metals and for severe machining operations , such as

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