Application of Minimum Quantity Lubrication (MQL) in plane surface grinding

The aim of this research was to acquire and formalise understanding of the Minimum Quantity Lubrication (MQL) technique in the surface grinding operation. The investigation aimed to show through experiment and theoretical study the effects of MQL on grinding process performance, measured in terms of tangential and normal forces, temperature and surface finish. A comparison of conventional, dry and MQL fluid delivery methods was performed. The experimental study was undertaken on a CNC grinding machine with integrated monitoring. A Taguchi methodology was employed to provide qualitative evidence of the strength of process parameters on performance indicators. The usefulness and promise of MQL was established. The study identified regimes of grinding where MQL can be employed successfully. This outcome is supported by results showing, in some applications, that MQL is comparable in performance to grinding under conventional fluid delivery. It was found that for some conditions MQL outperformed conventional fluid delivery. This was particularly so in the case of the tests with material EN8, (approximately 32 HRQ), where MQL was found to outperform conventional fluid delivery in almost all measures. As expected, not all conditions were in favour of MQL delivery and the reasons for this are discussed in detail in the thesis. A theoretical explanation for the efficient process performance is developed in relation to the experimental results obtained. The effects of variables such as DOC, dressing conditions, wheel speeds, workpiece speed and workpiece material are considered. It is reasoned that the MQL technique achieves efficient performance due to effective lubrication and effective contact region penetration by the fluid. Effective lubrication conditions were confirmed by highly competitive specific energy and grinding force measurements.