Experimental and Numerical Study of a Fixturing System for Complex Geometry and Low Stiffness Components

The production of freeform components is challenging, not only from the point of view of process optimization but also when it comes to the selection and design of the fixturing systems. Currently, most commercially available fixturing systems are difficult to conform to geometrically complex components; while the systems that manage to provide industrially feasible solutions (such as encapsulation techniques) present several limitations (e.g., high complexity, limited reliability, and risk of elastic deformation of the part). In this context, the present work proposes a simple, yet efficient, concept of a fixture capable of holding complex components through the use of compliant/deformable diaphragm elements. The fundaments of this innovative system (i.e., freeform diaphragm-based fixturing system) have been simulated through an experimentally validated finite-element (FE) model, with results showing a good agreement between numerical and measured data (displacement average error ϵ_av = 4.04%). The main interactions of the system with a workpiece (e.g., contact area and clamping force) have been numerically and experimentally studied, confirming the system's capacity to generate distributed clamping forces in excess of 1000 N. Based on the modeling activities, an advanced prototype for holding a “generic” freeform component was developed. Using this prototype, a repeatability study then showed the capacity of the system to deterministically position and hold complex geometries. Finally, the proposed fixturing system was thoroughly evaluated under demanding machining conditions (i.e., grinding), and the results showed the ability of the fixture to maintain small part displacement (d_x < 10 μm) when high cutting forces are applied (Max. F_R = 1021.24 N). Design limitations were observed during the grinding experiments, and the lineaments are presented in order to develop improved further prototypes. Overall, the proposed fixturing approach proved to be a novel and attractive industrial solution for the challenges of locating/holding complex components during manufacture.