Grinding and superfinishing are performed in parallel with each other on at least a portion of object portions, thereby shortening {HEAD ~ machining time} per {TAIL ~ workpiece} 
per
Grinding and superfinishing are performed in parallel with each other on at least a portion of object portions , thereby shortening { HEAD ~ machining time } per { TAIL ~ workpiece }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL