Using plunging-type testing to investigate process mechanics at micro scale machining

Abstract

In plunging-type tests, a cutting tool is given a sinusoidal movement as the work material with a web on its surface is rotated at a constant speed. If the amplitude and feed rate of the cutting tool and rotational speed of the work material are correctly set, the plunging test can be completed within a full rotation. As a result, a detailed investigation of different episodes of micro-scale machining, such as rubbing, plowing, and shearing, can be conducted with a single test. Combined with force measurements and cut chip morphology, the process mechanics can be investigated in detail. This study conducted plunging tests on an ultra-precision CNC with a diamond cutting tool on commercially pure titanium alloy. The differences in tangential and normal forces observed during plunge-in and pull-out periods corresponding to the same amplitude were analyzed using an analytical model. Resultant forces during the pull-out phase are larger than those observed in the plunge-in phase, attributed to an increase in cut chip thickness. A computational model of the plunging-type experiment has also been developed based on the findings of the analytical model. The proposed hybrid approach may be useful to improve identification of material constitutive model parameters based on micro scale machining experiments.