Grinding Burn
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Grinding Burn Konrad Wegener and Christoph Baumgart Institute of Machine Tools and Manufacturing, ETH Zürich, Zürich, Switzerland
Synonyms Thermal damage in grinding
Definition Grinding burn subsumes all unwanted changes in the surface and subsurface region of the workpiece due to heat release out of the grinding process. This comprises microstructural changes, high residual tensile stresses, and cracks (Karpuschewski et al. 2011). It has to be avoided by an appropriate choice of the process parameters, grinding tool, and coolant strategies. Process monitoring is necessary in order to avoid malfunctions of components due to the thermal damage. Grinding burn is in literature (e.g., Littmann 1953; Malkin 1974) used to characterize the visible surface damage. Most damage due to the grinding process is by the nature of the manufacturing process of thermal origin and can consist, besides oxidation of the surface, also of
metallurgical phase transformations, softening of the surface layer with possible rehardening, changes in residual tensile stresses, cracks, and resulting in a reduced fatigue strength (Malkin and Guo 2007). Because the same mechanisms are responsible for the annealing colors as for the subsurface damage, more modern literature (e.g., Höhn et al. 2011; Karpuschewski et al. 2011; Thiemann et al. 2013; Rowe 2014; Denkena et al. 2014) subsumes under “grinding burn” all effects visible or invisible on the surface and independent of the depth of influence. This definition is used throughout this entry. It is independent of materials and includes unwanted heat induced structural changes from grinding also for non-iron alloys, ceramics, and even for biomaterials.
Theory and Application Origin and Mechanism In cutting processes, nearly all mechanical power, which is introduced into the process zone, is converted into heat. This is split up in heat spreading into the tool, into the workpiece, heat which is extracted by chips and debris, and heat which is extracted by cooling for instance by metalworking fluids and surrounding media as shown in Fig. 1. In cutting processes with geometrically defined cutting edges as milling and turning, the heat input is less than in grinding, and the chips can remove a
# CIRP 2018 The International Academy for Production Engineering et al. (eds.), CIRP Encyclopedia of Production Engineering, https://doi.org/10.1007/978-3-642-35950-7_16786-1
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Grinding Burn
Grinding Burn, Fig. 1 Power balance of the grinding process. (Modified from Klocke (2009). Reproduced with kind permission of IWF, ETH Zürich). q_ tot = total heat generation, q_ c = heat flux into the coolant (or metalworking
fluid), q_ t = heat flux into the grinding wheel, q_ s = heat flux into removed material, q_ w = heat flux into the workpiece, Fc = cutting force, vc = cutting speed
high share of the thermal energy from the process zone. Therefore, in many cases dry cutting is possible. However, in conventional grinding the introduction of heat into the workpiece with typically about 55% of the chip formation energy an
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