Analysis of Tool Wear: Part II: Applications of Flank Wear Models

For machining with cemented carbides and ceramics, a quantitative assessment of tool failure at the flank for establishing “limit criterion” is necessary. The arbitrarily chosen flank wear limit for all cutting speeds is not valid at higher cutting speeds because of the earlier appearance of the “inflection point” which is often taken as criterion of flank-failure. In this paper, proceeding from the basic physical model of flank wear described in Part I of the paper (ASME Paper No. 68—WA/Prod-5), tool-life relations in the form of Taylor’s equations have been theoretically developed, the parameters of which have been compared with, experimental results. Further, the critical points of inflexion where the flank-wear characteristic enters temperature sensitive region resulting in accelerated wear have been uniquely defined. The location of these critical points have also been verified experimentally.

Analysis of Tool Wear—Part I: Theoretical Models of Flank Wear

Cutting tools of sufficient strength against failure by brittle fracture or loss of “form stability” through rise of interface temperatures, still continue to fail by a process of “wear,” which is loss of cutting tool material through gradual interaction between the work and the tool material. Such wear can take place either at the principal flank surface or at the top face of the cutting tool for roughing and semiroughing cuts. Wear may also occur at the auxiliary flank surface resulting in grooving wear during fine machining or machining of high strength materials. The causes for such wear processes include (i) mechanical interaction (abrasion or adhesion and transfer type), (ii) thermochemical interaction (diffusion or chemical reaction). As a part of this investigation on tool wear, two theoretical models have been proposed for explaining mechanical wear at the flank surface. These models explain the nature and characteristics of wear growth and the sensitiveness and dependence of interaction phenomena between the tool-work pair.