3.3 Location principle of workpiece In order to fulfill the machining requirement of a certain job, a relatively accurate position of the workpiece in a machine tool in relation to the cutting tool during the metal cutting movement must be ensured. The following three conditions must be satisfied when fulfilling such a practical function, which are （1）The accurate position of a batch of workpieces in relation to the jigs or fixtures ； (2) The accurate position of the jigs or fixtures in relation
