An investigation into parallel and cross grinding of aspheric surface on monocrystal silicon

Cross and parallel grinding modes are two typical general grinding modes for aspheric surface in vertical wheel spindle grinding system. In this paper, roughness, surface profile, form accuracy, and wheel wear of the ground aspheric surface utilizing the cross and parallel grinding methods are compared and investigated. Firstly, the maximum undeformed chip thickness of aspheric surface was analyzed in the two grinding modes. And then, the precision grinding of mono-crystal silicon for aspheric surface and wheel wear experiments was carried out with the same grinding parameters. Experimental results revealed that the cross grinding mode was advantageous over parallel grinding in terms of achieving precision aspheric surface with a roughness (Ra) of 20.1 nm, form accuracy (PV) of 235 nm, and a steady surface. The change of the maximum undeformed chip thickness in grinding process caused the increased surface roughness from the edge to the center. And without considering the influence of the wheel arc profile form error, better form accuracy was obtained by cross grinding. Besides, the wheel wear modes were significantly different in the two grinding modes. This study gives an indication of the strategy to follow to achieve high-quality ground aspheric surfaces on brittle materials.