Effect of system compliance and workpiece dynamics on machining error

Purpose - Source errors in a workpiece fixture system include the compliance of the workpiece fixture system and workpiece dynamics. The purpose of this paper is to study the relative significance of these two. The findings would help to achieve computational economy in optimization of fixture layout and/or clamping forces. Design/methodology/approach - Different layouts are generated with the help of a reconfigurable fixture set up and a slot is end milled on the workpiece. Using these data and the finite element software AND'S, the machining error due to system compliance is computed. The machining error due to workpiece dynamics is obtained using a data acquisition system with the Lab View software. These steps are repeated for different clamping forces and the relative contribution of these two sources to the overall machining error is studied. Findings - Results show that the system compliance is much smaller in magnitude compared to workpiece dynamics and hence does not contribute appreciably to the overall machining error. This leads to the conclusion that, for bulky and stiff parts, evaluation of the machining error due to compliance can be done away with. Originality/value - The paper's originality lies in comparing the two sources of machining error using experimental work and finite element models. To the author's knowledge such a comparison has not been reported in the literature.