A customer of ours was manufacturing hydraulic cylinders made of 4340 steel, using a Mazak Qualiturn CNC Lathe. The cylinders for this customer required a surface finish of 16 Ra microinch (0.4 Ra) or better. Originally, the customer was sub-contracting other firms to grind the parts to achieve the required surface finish before their chrome plating operation. This was both costly for our customer and extremely time consuming since they could not control when their parts were finished, resulting in long and uncertain lead times. Here is the data for their original turning operation: