Eventos Anais de eventos
COBEF 2023
12th Brazilian Congress on Manufacturing Engineering
Characterization of the nature of the phenomena that affect the surface integrity in hard part turning with PCBN tool
Submission Author:
Clarianne Natali de Campos , SC
Co-Authors:
Clarianne Natali de Campos, Denis Boing, Rolf Schroeter
Presenter: Clarianne Natali de Campos
doi://10.26678/ABCM.COBEF2023.COF23-0317
Abstract
High performance components in mechanical systems need to have an adequate level of surface integrity in order to reach the required performance, the fatigue life or prevent premature failure. Among these, transmission components stand out, which are typically finished by grinding and/or hard turning using PCBN (Polycrystalline Cubic Boron Nitride) tools. Despite the advantages of hard turning it is known that this is a thermomechanical process, a characteristic that creates conditions for changes in surface integrity, such as microstructural alterations and modification of the residual stress profile in the surface layers and subsurface of the components. Evaluating industrial applicability of hard turning two main tooling concepts are used: standard solutions (e.g., use of ISO inserts) typically rely on cutting speed to achieve adequate levels of productivity, with such a choice having the highest incidence of thermal effects. On the other hand, solutions that improve productivity by increasing the feed rate and reducing the cutting speed cause an increase in the contact area between the tool and the workpiece and, consequently, the greater the effects of mechanical loads on the process. In this perspective, the present work aims to evaluate the influence of different cutting parameters on the phenomena perceived in the surface integrity in the hard turning of AISI 4340 steel (60 HRC) with PCBN tool. For this, three distinct sets of parameters were defined that, theoretically, can generate different responses in the machined surfaces: a solution that foresees the increase of cutting speeds, another that uses low cutting speeds and high feed and cutting depth and a last solution with recommended parameters for finishing hardened steels. For this, turning tests were carried out with AISI 4340 steel with PCBN tools. The machined workpieces and after the metallographic procedure were evaluated with the aid of optical microscopy and scanning electron microscopy (SEM). From the analyses, it is expected to observe that the use of high cutting speeds promoted the elevation of the temperatures of the tool-workpiece interface, inducing, thus, thermal phenomena. With the increase in feed and depth of cut and reduction in cutting speed and, with the consequent increase in the contact area of the tool, greater will be the levels of plastic deformation and mechanical phenomena incident on the surface. Finally, with the use of finishing conditions, both thermal and mechanical phenomena will coexist, given the levels of deformation generated and temperatures reached in the process.
Keywords
surface integrity, Hard Part Turning, PCBN tool, Industrial solutions.
