The friction surface is rough with thick and deep grinding cracks
. Because the secondary transition temperature of PMMA is low, the friction surface of PMMA is easy to stick some debris.
Grinding process is accompanied by high temperature in cutting area that can cause the forming of heat defects (grinding cracks
) and tension tempers in surface layer that bring to substantial reduction of endurance of details (Yakimov, 1986).
Specifically, he wanted to avoid the potential for grinding cracks
and over-tempering or under-tempering caused by grinding heat.