The impact of Initiative Locating and State Memory fixturing (IL&SM ) on workpiece location position with CNC machining

The Initiative Locating and State Memory fixturing (IL&SM) is a new fixturing concept that adopts the technique of freezing and encapsulating the workpiece in space to realize locating and clamping. IL&SM solves the locating problem of the irregular parts which are often difficult or impossible to hold with conventional vices or toe-clamps. As well as having a locating function, fixtures must also ensure that the manufactured workpiece quality can be achieved. In this paper, the influence of the intrinsic inaccuracy of IL&SM box involved in the manufacture and fixing is presented on position accuracy of machined feature in workpiece during multi-operation changing. Based on rigid body kinematics with small error assumption and homogeneous coordinate transformation method, the general workpiece position error model is created as a function of the dimensional variables of IL&SM box. The analysis instance is served as the essential theoretical technical support to prove the presented algorithm effectiveness. Thus the theoretic model reported here has made a new contribution in the application and generalization of error compensation technology to increase capability of the IL&SM technique.