Workpiece Material Removal and Lapping Wheel Wear in Plane and Plane-Parallel Lapping

Abstract

In plane and plane-parallel lapping, workpiece material removal and lapping wheel wear depend on each other and have to be evenly distributed. To obtain flat workpieces and small thickness deviations, a flat lapping wheel is required. To get a flat lapping wheel and therefore workpieces of high quality one has to evaluate the errors on the lapping wheel surface as a function of machining parameters. The kinematic of a single wheel lapping machine can he characterized by the ratio λ of the angular velocities of the dressing ring (possibly driven) and of the lapping wheel. It is easy to compare other machine concepts with single wheel or different machine types, Recent investigations have shown that lapping grains sticking to the workpiece (lapping wheel) result in micro-cutting at the lapping wheel (workpiece) and that grain rolling between workpiece and lap leads to surface interactions and material removal. Every workpiece spot generates a trace on the lapping wheel. On the other hand, every lapping wheel spot generates a trace on the workpiece. The paper shows a calculation procedure to evaluate workpiece and lap wear. Some examples of calculations show how to control the shape of the lap by controlling the workpiece distribution and the ratio λ. λ is the most important parameter for automatic process control. For this, inprocess or intermittent lap shape control as a prerequisite. First considerations on inprocess control are presented in the paper.