A finite element model to analyze effect of clamping sequence, clamping pre-loads and machining loads (forces) on the surface error for face-milled workpieces was developed. A compliant test part was used to test and demonstrate the predictive capabilities of the model. Experimental measurements of surface deflections/errors after clamping, and after machining were compared with the finite element predictions. Both predicted peak-to-valley surface error values and surface error patterns for ZXY clamping sequence were in good agreement with the experimental measurements.
The effects of fixture compliance, workpiece-fixture contact geometry (point / area contact), and clamping preloads on the surface error predictions were also studied. The clamping preloads have the most significant impact on the surface error during fixturing of flexible parts, followed by effect of contact area geometry. Fixture compliance, however, does not significantly affect the surface error in case of structurally compliant parts.