Fixture analysis under dynamic machining

This paper presents a future generation methodology that takes into account dynamic machining conditions which occur when the machining forces and moments travel or change with respect to time. This is more realistic than previous systems which have treated the machining conditions as static. It also increases the difficulty of fixture generation since the machining conditions are always changing. In this paper, a comprehensive methodology based on linear programming has been developed to circumvent this problem. It takes into account the maximum forces and moments during all time and the desirable characteristics of a fixture such as: positive reaction forces at the locators for all time, deterministic positioning, strong accessibility, stability of the workpart in the fixture while under no external forces, and a positive clamping sequence. In order to reduce the total computation time, the linear programming technique is used to formulate the deterministic positioning and accessibility characteristics of a fixture. Finally, force planes, similar to distributed load diagrams, are created to act as guides in the slight repositioning of locators for modular fixturing. Two case studies are presented to demonstrate the capabilities of the methodology.