Machining fixture verification for linear fixture systems

This paper presents a fixture configuration verification methodology that takes into account dynamic machining conditions--including the effect of dynamic gravitational forces--in the verification process. The fixture verification system is modelled as a linear optimization problem with respect to minimum clamping forces. The method provides a simple and effective means for (a) verifying whether a particular fixturing configuration is valid with respect to locating stability, deterministic workpiece location, clamping stability and total restraint; (b) identifying which locator loses contact with the part for an invalid fixture configuration; (c) identifying which clamp needs to be replaced; and (d) determining the minimum clamping forces to restrain the piece during the entire machining process. Since a fixture configuration design is validated not only under a given cutting direction, but also under an inverse cutting direction, this allows designers to understand thoroughly whether the fixture configuration is valid and what the sufficient dynamic clamping forces are for the fixture system to withstand unpredicted machining forces over the entire machining time. Hence, it makes the verification system more robust and reliable. Two case studies are included to demonstrate the effectiveness and the capabilities of the methodology.