Cylindrical Grinding is a process used to further finish parts that have been approximated during final production (i.e., crankshafts, axles, bushings and bearings). Like with centerless grinding, there are two types of cylindrical grinding - internal and external. The internal grinding is much like the boring operation where the part is held in a chuck and rotated. External grinding resembles the turning operation where the machines used looks like lathes but the tool post gets swapped for a grinding wheel.