Chip Breaking Parameter Selection for Constant Surface Speed Machining

Abstract

Modulated tool path (MTP) chip breaking is a lathe machining technique which produces chips of a predetermined length to reduce the risk of damage to the tool or the work piece caused by chip entanglement. Individual chips are formed by repeatedly interrupting chip formation through CNC commanded tool oscillations superimposed in the tool feed direction. Previous work has shown that the chip length and part surface finish quality are dependent on the tool oscillation frequency relative to the spindle speed (OPR), and the oscillation amplitude relative to the global feed per revolution (Raf). Apart from chip length and surface quality, the dynamic capabilities of the machine must be considered when selecting MTP parameters, OPR and Raf. The dynamic limitations of the machine will limit the available range of tool oscillation frequencies and amplitudes. In this paper, the factors which affect the MTP parameter selection process are discussed, and a process for selecting these parameters automatically based on multiple constraints and criteria is presented for constant surface speed MTP machining.