Optimisation of machining fixture layout under multi-constraints

Fixture layout including locator layout and clamp layout plays a vital role in fixture performance. Current researches have been focused on fixtures for components with regular geometry, the results of which are not always applicable for components with complex geometry. This paper presents a methodology of fixture layout optimisation carried out in consideration of the repeatability, immobility and stability of fixturing. The locator layout is optimised based on the criteria of workpiece repeatability and location accuracy. The clamp layout optimisation offers a method to minimize the magnitude of the clamping force. The procedure of clamp optimisation is (1) to find the feasible clamping position in terms of the immobility requirement; (2) to get the best clamp among the feasible clamping positions under constraint of the stability. The optimal fixture layout is considered in a global range and is especially suitable for the workpiece with complex surfaces. A fixture layout design for the aerofoil of a turbine blade is analysed as an example, and the optimal fixture layout is demonstrated.