ABSTRACT
In this work, cutting fluid emulsion was developed from soya beans and the performance of the developed cutting fluid was evaluated by comparison with the conventional cutting fluid (control sample), using its ability to effectively perform as coolant during machining operation. The machining operation employed was the turning operation in which chips produced were collected and their surface finishes measured. The chips collected were evaluated for chip thickness ratio. Also, the temperature variations during cutting operation were measured using an infra- red gun thermometer. Temperature, surface finishing as well as chip formation rates using the developed cutting fluid under different cutting speed (rev/min), feed rate (mm/rev) and depth of cut (mm) was compared with that of the conventional cutting fluid. The average temperature of the work piece when developed cutting fluid was used as cutting fluid was 53.13 oC and that of the conventional cutting fluid was 54.7 oC. The result are very close, hence it shows better result in conducting heat away from cutting region. The developed cutting fluid gave an average high chip thickness of 0.446 mm while that of the conventional cutting fluid was found to be 0.316 mm. The high chip thickness of the developed cutting fluid is probably due to its better lubricating ability which allows easier and deep penetration of cutting tools. The average viscosity of the developed cutting fluid was found to be 31.1 poise at 29 oC, while the convectional cutting fluid was 47 poise at 29 oC. Low viscosity means high viscosity index, the developed cutting fluid has tendency to be fluid at higher temperature than the convectional fluid. In corrosion measurement, the developed cutting fluid shows no sign of corrosion; hence, the fluid has good ability to inhibit corrosion than the convectional cutting fluid.
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TABLE OF CONTENTS
Title page i Declaration ii Certification iii Dedication iv Acknowledgement v Abstract vi Table of Content vii Nomenclature viii List of Figures ix List of Tables x List of Plates xi CHAPTER ONE 1.0 Introduction 1 1.1 Background of the Study 1 1.2 Statement of the Problem 2 1.3 The Present Work 2 1.4 Aim and Objectives of the Work 3 1.5 Scope of the Study 3 1.6 Justification 4 CHAPTER TWO 2.0 Literature Review 5 2.1 Introduction 5 2.2 Cutting fluid 6
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2.2.1 Characteristic of a good cutting fluid 7 2.3 Function of cutting fluid 7 2.4 Types of cutting fluid 8 2.5 Classification of cutting fluid 9 2.6 Importance of cutting fluids 10 2.7 Additives for lubricants 10 2.7.1 Friction modifiers 11 2.7.2 Anti – wear additives 11 2.7.3 Extreme pressure (EP) additives 12 2.7.4 Rust and corrosion Inhibitors 12 2.7.5 Anti – oxidants 12 2.7.6 Detergents 13 2.7.7 Dispersants 13 2.7.8 Pour point depressants 13 2.7.9 Anti-foaming agents 13 2.7.10 Viscosity Index Improver 14 2.8 Selection of cutting fluids 14 2.9 Soya beans as vegetable base oil 17 2.10 Cutting fluid Formulation and Characterization 17 2.11 Surface roughness and classification 18 2.12 Methods of evaluating surface roughness 19 2.12.1 Centre line average method (CLA) 19
2.12.2 Peak to valley height 20
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2.13 Measurement of surface finishes 20 2.14 Effect of cutting speed on surface finish 21 2.15 Effect of depth of cut and feed rate on surface finish 22 2.16 Machining processes 23 2.17 Force effects 25 2.17.1 Forces involved in machining processes 25 2.17.2 Determination of Shear plane angle 26 2.17.3 Determination of shear strain 26 2.17.4 Forces acting on chip 27 2.17.5 Coefficient of friction 27 2.17.6 Shear stress 27 2.17.7 Forces in metal cutting 28 2.17.8 Merchant‟s shear angle relationship 29 2.18 Cutting temperature 29 2.18.1 Chip thickness ratio 30 2.19 The effects of properties of cutting fluids during machining operation 30 2.20 Review of past works 32 CHAPTER THREE 3.0 Materials and Methods 34 3.1 Materials 34 3.2 Equipment 34 3.3 Method of Developing Cutting fluid 34 3.4 Method of Extracting Soya bean Oil 35
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3.5 Measurements of Surface finish 35 3.6 Quality of cutting fluid 36 3.6.1 pH 36 3.6.2 Determination of acidic value 36 3.6.3 Viscosity 36 3.6.4 Corrosion 37 3.7 Performance and Evaluation of Cutting Fluids 37 3.7.1 Experimental procedure 38 CHAPTER FOUR 4.0 Results and Discussions 40 4.1 Acidic value 40 4.2 pH measurement 40 4.3 Corrosion measurement 41 4.4 Measurement of viscosity 41 4.5 Discussion of results 47 4.5.1 Acidic value 47 4.5.2 Corrosion 48 4.5.3 Viscosity 48 4.5.4 Effects of the lubricants on chip formation 48 4.5.5 Effects of the lubricants on surface finish 49 4.5.6 Effects of lubricants on temperature 49
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4.5.7 Effect of cutting speed on surface finish and chip formation 49 CHAPTER FIVE 5.0 Conclusions and Recommendation 5.1 Conclusions 51 5.2 Recommendation 52 References 53 Appendix 57
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CHAPTER ONE
INTRODUCTION 1.1 Background of the Study The use of cutting fluids in metal cutting was first reported in 1894 by F. Taylor who noticed that cutting speed could be increased by 33% without reducing tool life by applying large amounts of water in the cutting zone (Ávila and Abrao, 2001). Cutting fluids increase tool life and improve the efficiency of the production systems providing both cooling and lubrication of the work surface. Cutting fluids are used to reduce the negative effects of heat and friction on both tool and work piece. Cutting fluids produce three positive effects on the process: heat removal, lubrication on the chip–tool interface and chip removal (Lopez de Lacalle et al., 2006). However, the advantages caused by the cutting fluids have been questioned lately, due to the several negative effects they have caused to in the environment and worker‟s health. When inappropriately discharged, cutting fluids may damage soil and water resources, causing serious environmental impact. On the shop floor, machine operators may be affected by negative effects of cutting fluids, such as skin and respiratory problems (Lopez de Lacalle et al., 2006). In order to make the machining process more ecologically friendly, a near-dry application of lubricant have been accepted because of its environmentally friendly characteristics (Sokovic et al., 2001, Dhar et al.,2006 and Suda et al.,2004). But, depending on the machining process, to reduce or eliminate cutting fluids use is not possible. For these cases it is necessary to develop an alternative solution in order to avoid environment and heath damage.
The use of vegetable oils may make possible the development of a new generation of cutting fluids of high performance in machining combined with good environmental friendliness.
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Interest in vegetable oil-based cutting fluids is growing. Compared with mineral oil, vegetable oil may enhance the cutting performance, extend tool life and improve the surface finishing according to industrial study (Woods, 2005). Although, they have many environmental benefits, vegetable oils are more susceptible to degradation by oxidation or hydrolytic reactions. Therefore, the correct selection of the vegetable substance, the pH of the resulting solution and its control are important issues (Woods, 2005). 1.2 Statement of the Problem Cutting fluids based on minerals oils are normally used for their low costs and chemically stability. However, the present trend towards new types of cutting fluids based on vegetable oils is clearly justified by their higher biodegradability and lower environmental impact. Chemically based cutting fluids presently used have adverse effects on the operator and the environment compared to the environmentally friendly vegetable- based cutting fluids. The performances in areas of surface finish, chip thickness and temperature of these two types of oils (chemically based cutting fluid and vegetable- based cutting fluid) are similar. Issues of environmental pollution and hazard to workers have arisen and there is need to develop safe and efficient metalworking fluids which are environmentally friendly. (Lopez de Lacalle et al., 2006). 1.3 The Present Work This present work is concerned with the development of a vegetable based cutting fluid using soya bean oil because of its availability and high fatty acid content which is responsible for the oiliness and lubricity, lubricant additive to enhance its performance for the machining process. This product is tested in turning operations using mild steel to verify its performance.
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1.4 Aim and Objectives of the Research The aim of this work is the development of environmentally friendly biodegradable cutting lubricant from soya beans (glycine max). The specific objectives of the research are:
i. Developing biodegradable cutting fluid from vegetable based oil (soya beans) that is environmentally friendly.
ii. Carrying out performance evaluation of the developed cutting fluid in turning operations based on the surface finish, chip thickness ratio, amount of heat generated during the machining operation and chemical properties (corrosion, pH values, acid value and viscosity) of the developed cutting fluid.
iii. Comparing the physiochemical properties of the developed cutting fluid to that of the conventional cutting fluid.
1.5 Scope of the Work The work done cover the following areas;
i. Vegetable based cutting fluid was developed
ii. Determination of physicochemical properties of the developed cutting fluid was carried out.
iii. Performance evaluation of the surface finish, chip thickness ratio and the amount of heat generated during machining process with the cutting fluid was carried out.
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1.6 Justification
(i) The search for biodegradable cutting fluid to replace the mineral oil based cutting fluid was undertaken.
(ii) This study aims to ascertain the economic and technological viability of local oils as a useful substitute for present cutting fluids.
(iii) The need to produce environmentally biodegradable cutting fluid is high due to the fact that convectional cutting fluids have adverse effects on operators and environment. (Lopez de Lacalle et al., 2006).
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