Part 2: Study of the Finish Produced in Surface Grinding

The principal attempts to analytically predict the roughness of a ground surface in terms of wheel geometry and operating parameters are reviewed, and the number of cutting points per square inch of wheel face is identified as a quantity requiring further attention. A new dynamic method of determining the variation of cutting points per square inch with distance from the outermost grain is described and illustrated. Two methods of predicting the peak-to-valley roughness (h) of a ground surface are presented. The first, which assumes all grains to lie in the same plane and ensures volume continuity, leads to values which are somewhat lower than measured values. The second method, which assumes grains at different levels to be evenly spaced, involves a calculation for the transverse scratch pattern assuming grain geometry to be exactly reproduced in the finished surface. It leads to values of (h) that are somewhat too high. The roles of vibration, spark-out, and the indirect influence of the wheel depth of cut are discussed relative to surface roughness. The analytical results are found to be in relatively good agreement with the comprehensive experimental study presented in Part 1.