Chemical reactions arise from the reactivity between the system components. Therefore, low chemical reactivity between all system components including grits, tool bonding, workpiece material, cooling lubricants and their additives is favored (Fig. 7.29). In addition, low mechanical pressure slows down chemical reactions as does low heat, which has been tackled earlier.
Brinksmeier and Wilke [BRIN04] gave case studies about chemical reactions within grinding technology. There is still big demand for research. The effect of
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Fig. 7.29 Chemical reactions (diagram follows Fig. 7.23) |
contact time between grits and workpiece needs to be discussed in further grinding models.
Depending on the process temperature, the mechanisms of cooling lubricant/part surface interaction change. At low temperatures, physisorption and chemisorption occur resulting in weakly linked sorption layers [BRIN00]. At higher processing temperatures, reactions between additives in the cooling lubricant and the part surface can take place and result in reaction layers on the workpiece [BRIN00].
In chip formation, many side effects overlay, such as heat generation, heat reduction, chemical reactions, mechanical load, and disturbances. Often these side
effects are tackled separately, although grinding is a complex superposition of all these physical effects. Mahdi and Zhang [MAHD00] examined, for example, how the temperature gradients, mechanical stresses and phase transformations affect residual stresses in grinding. Duscha et al. [DUSC11] used an FEM-approach to simulate phase transformation during grinding, adding residual stresses resulting from phase transformations. Brinksmeier et al. [BRIN03] investigated the phase transformation of steel during grind-hardening which involves multiple effects on surface integrity. Yet, very few models take the coupled interaction of the effects during chip formation into account [HEIN09b].