Abstract: This paper takes the aerocraft arc-shaped workpiece for the study on NC machining deformation and the reason which leads to machining deformation. Three aspects are discussed, which include analyzing cutting force’s contribution to deformation in NC machining process, researching the distribution and influence of residual stresses which lead to workpiece deformation and researching the fixture layout which affects NC machining deformation of large structure part. These three aspects of actual machining process are considered all together. The computing physical simulation model is established to simulating and predicting machining deformation.Several methods which solve the problem of deformation are proposed.

Key words: NC machining, deformation, simulation, residual stress, arc-shaped workpiece