Soutenance mémoire
Effect of cutting parameters on surface roughness when using continuous pump
Machining lubrication modes
The important roles of cutting fluids during machining are decreasing the friction and the temperature by heat dissipation which increases tool life. However the use of cutting fluids is hazardous to operator health and the environment. Furthermore machining cost is anticipated when using cutting fluid. To reduce the influence of cutting fluids on environment, the lubricants are improved by biodegradable fluids. However there is still bacterial contamination problem that is greatest problems encountered during lubricated machining. To eliminate all of these problems, other machining techniques such as dry and semi-dry machining or minimum quantity cooling lubricant (MQCL) are proposed. In cases with high heat generation, traditional oil can be 7 replaced with an emulsion which has a higher heat capacity due to its water content. The process in this case is referred to as minimum quantity cooling (MQC), making MQC distinct from MQL (minimum quantity lubrication). MQC is still largely unexplored, although it could provide a solution to processes with high heat generation (Diakodimitris, Hendrick and Iskandar) These new methods help us to have clean machining and to increase and sometimes completely eliminate the serious problems associated with traditional machining. Most of these problems are caused by metallic particles and dust emissions generated during lubricated cutting
Semi-Dry
In the metalworking industries, the health of operators and environmental pollution are affected by cutting fluids. In order to reduce these problems, the new method of machining, called Minimum Quantity Lubrication (MQL) is used. With respect to practical point of view, MQL cutting consumes an average of 50 ml of lubricant per processing hour. However, for certain operations (e.g. when using the workpiece with diameter of 40mm or larger), the lubrication consumption rate may exceed 150 ml/h (Unfallversicherung, 2010). Most important advantage of MQL system is that the lubricant supplies directly to the contact area. Due to this small droplet, the thermal shocking of the cutting tool is reduced, which increases the tool life and performance of its operation (Jun et al., 2008). On the other hand, the MQL has also the disadvantages like the inability of complete heat transfer and moving out the chips from the cutting zone which is the cause of part corrosion. In this method, the nozzle must be located not more than 1 or 2 inches from the tool which enables the operator to precisely adjust the nozzle. The performance of MQL machining depends on many factors including lubricant; tools and suitable devices must be compatible. It is also very important that the conditions be properly inspected by the qualified machine operator. Dry machining and MQCL are possible for almost every cutting and non-cutting processes as well as turning, drilling, reaming, thread cutting, thread rolling, milling, hobbling, sawing and broaching
Conclusion of literature review and refining of problematic
According to the literature review about MQCL and comparing it with dry and wet applications, it is concluded that MQCL method can improve the cutting performance more than the other machining modes because supplying the lubricant directly to the cutting zone reduces the cutting temperature which improves the chip-tool interaction. Because of tool wear reduction, MQCL improves tool lifetime. It leads also to better surface finish as compared with dry and wet machining. The previous studies have shown that dry and semi-dry machining processes are environmental friendly and less dangerous. However, in some conditions, the large amounts of the fine and ultra-fine particles are produced. This problem in addition of particle emission hazardous, the investigation of particle sizes has become crucial. To accomplish this measurement, laser based techniques are very useful. The unique nature of the laser allows the accurate in-situ measurements in different environments where using the other kinds of particle sizing systems are impossible because of the various difficulties such as high temperature and risk of pollution which is dangerous for environment. Considering the importance of the investigation of droplet size distribution and particle size measurement in different research and industrial applications, the principles and the applications of different atomization processes have been reviewed. According to the investigations and the empirical equations obtained from the Sauter mean diameter « d32 », the most important parameters to control the mean droplet size are as follow:
• Liquid and gas mass flow rates and air to liquid mass flow rate ratio (ALR);
• The characteristics of the liquid such as viscosity, density and surface tension;
• The atomizer type such as plain-jet, prefilming and etc.
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Table des matières
INTRODUCTION
CHAPTER 1 LITERATURE REVIEW
1.1 Introduction
1.2 Turning
1.3 Machining lubrication modes
1.3.1 Wet
1.3.2 Dry
1.3.3 Semi-Dry
1.3.4 Properties of lubricant
1.4 Atomization
1.4.1 Definition
1.4.2 Mechanism of atomization
1.4.3 Theoretical and experimental studies (Theories)
1.4.4 Atomization Summary
1.5 Atomizers and pulverization
1.5.1 Introduction
1.5.2 Different lubrication systems
1.5.3 Nozzle performance properties
1.5.4 Different types of atomizers
1.5.5 Common features of different twin-fluid atomizers
1.6 Prediction of mean drop size and drop size distribution
1.6.1 Introduction
1.6.2 Definition
1.6.3 The empirical correlations related on the mean drop diameter
1.6.4 The effects of variables on mean drop size
1.7 Cutting parameter effects on machining quality characteristics
1.7.1 Cutting parameter effects on Surface Roughness
1.7.2 Cutting parameter effects on cutting tool temperature
1.7.3 Cutting parameter effects on aerosol emission
1.8 Conclusion of literature review and refining of problematic
CHAPTER 2 INSTRUMENTS AND EXPERIMENTAL PROCEDURES
2.1 Introduction
2.2 Instruments
2.2.1 Injectors
2.2.2 Laser diffraction system
2.2.3 Pumps (GLS, SLS1.2-2 and DDA pumps) and flow sensor
2.2.4 TSI 8532 DustTrak – II aerosol monitor
2.2.5 Profilometer
2.3 Installation and experimental procedures
2.3.1 Particle sizing and injection angle measurement
2.3.2 Machining quality characteristics measurements
2.4 Conclusion
CHAPTER 3 EFFECTS OF ATOMIZER GEOMETRIES ON PARTICLE SIZING AND INJECTION ANGLE
3.1 Introduction
3.2 Effects of liquid orifice diameter
3.2.1 Sauter mean diameter (SMD)
3.2.2 Injection angle
3.3 Effects of atomizer length
3.3.1 Sauter mean diameter (SMD)
3.3.2 Injection angle
3.4 Effects of liquid orifice shape
3.4.1 Sauter mean diameter (SMD)
3.4.2 Injection angle
3.5 Atomizer geometry effects on SMD and injection angles when using continuous pump and high liquid flow rates
3.5.1 Liquid orifice diameter effects
3.5.2 Atomizer length effects
3.5.3 Liquid orifice shape effects
3.6 Validation of the Sauter mean diameter (SMD) experimental results
3.7 Conclusion
CHAPTER 4 MACHINING PERFORMANCE WHEN TURNING AA6061-T6 WITH PULSED AND CONTINUOUS COOLING/LUBRICATION
4.1 Introduction
4.2 Surface roughness investigation using the pulsed and continuous pumps when turning aluminum alloy 6061-T6
4.2.1 Introduction
4.2.2 Effect of cutting parameters on surface roughness when using pulsed pump
4.2.3 Effect of cutting parameters on surface roughness when using continuous pump
4.3 Cutting tool temperature and dust concentration investigation using the continuous pumps when turning of aa6061-t6
4.3.1 Introduction
4.3.2 Effect of cutting parameters on tool temperature
4.3.3 Effect of cutting parameters on dust concentration (Dc)
4.4 Multiple response optimization of machining
4.4.1 Introduction
4.4.2 Desirability Function
CONCLUSION
RECOMMENDATIONS
APPENDIX 1
APPENDIX 2
BIBLIOGRAPHY
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