In creep feed grinding, surface roughnesses are much smaller due to the engagement of a higher number of cutting edges and due to smaller feedrates than in the case of reciprocating grinding. Since the functional surface properties of a workpiece are often important, creep feed grinding has a clear advantage here. This can be traced back to the kinematics of creep grinding. Those grain cutting edges, which do not completely chip off due to their position in the bond or to advanced wear, through plastic deformation, contribute to the smoothing of the workpiece. On the other hand, there are higher forces and thermal stresses that require much higher static and dynamic rigidity and effective driving and ancillary units of the grinding machine. In the case of reciprocating grinding, the number of cutting edges participating in the cutting process is higher in relation to the material volume. Based on the short contact time of grain and workpiece, a different surface is generated. The plastic curl-ups on the workpiece are, unlike in creep feed grinding, not smooth — ened by the simultaneously engaged neighboring cutting edges but pushed away into neighboring grooves by subsequent chipping processes. This results in temporary coverage of cut grooves by plastically deformed material. These curl-ups additionally increase surface roughness. Due to the stress during the process, these curl-ups do not correspond to the basic material, and there is no material cohesion as in the original state any more. Thus, there is an increased risk of particles detaching from the surface during subsequent use, for example, in the case of sliding bearing surfaces often machined by grinding, and result in component breakdown due to friction and squeezing [Schleich 1980].
The selection of the abrasive is mainly based on the properties of the workpiece material and on the secondary conditions during the grinding process, for example, the use of cooling lubricant. The larger creep feed grinding forces and thermal stresses in the working zone, however, require an adjusted bond of the grinding wheel.
In the case of reciprocating grinding, the wheel must absorb the impact stress due to the changing engagement of synchronous and counter rotation and to the high grinding forces at the single grain. In the case of creep feed grinding, impact and single grain forces are lower. In this case, high thermal stresses must be absorbed in the working zone.
A further aspect influencing wheel selection is the chip shape, which is crucially affected by the workpiece material. In the case of reciprocating grinding, there are usually short, thick chips. In contrast, chips are relatively thin and long in the case of creep feed grinding [Uhlmann 1994a]. The combination of abrasive grain/bond must be selected in a way that chips can be easily evacuated from the working zone without additional friction and squeezing on the workpiece and/or clogging of the grinding wheel. Therefore, there must be sufficient chip space available. An open structure of the grinding wheel allows for a significant increase of flowrate in the working zone through the cooling lubricant transport in the pores. This results in an enhanced heat transport, which is of special significance in the case of creep feed grinding.