Extension of basic geometric analysis of 3-D chip forms in metal cutting to chips with obstacle-induced deformation

Abstract In machining, chips are known to break mainly because of obstacle-induced deformation. Recently, the present authors had reported on a new and basic geometric analysis of 3-D chips in the absence of deformation after separation from the tool rake face. This paper continues the analysis to cover the full lifecycle of chips subjected to obstacle-induced deformation. The main contributions of this paper are the identification of the geometric properties that are likely to be preserved during obstacle-induced chip deformation and their implications, and the utilisation of these properties to obtain insights concerning the geometry of the tool–chip contact area. The new theoretical findings are verified against empirical data obtained through manual deformation of chips, video recordings of the development of obstructed chips, and the use of a specially prepared grooved tool that imposes a predetermined side-curl on the chip.