Cutting Parameters Optimization for Minimal Total Operation Time in Turning POM-C Cylindrical Stocks into Parts with Continuous Profile Using a PCD Cutting Tool

Abstract

Turning is a complex machining process that can be characterized by a number of performances for a given machining system, workpiece material, cutting tool, and selected cutting regime. In addition to the characteristics of the machined surface quality, the estimation of machining time is particularly important for manufacturers, since machining time is directly related to other important performances of the turning process, such as productivity, cost, and energy consumption. In this paper, a model for estimation of total operation time in turning of a part with continuous profile, made of polyoxymethylene copolymer (POM-C), using a polycrystalline diamond (PCD) cutting tool, was developed. Face centred central composite design (CCD) and Box–Cox transformation approaches were applied for that purpose. The developed model was then used as the objective function in the proposed optimization model, which also included three practical constraints related to quality of the machined surface (surface roughness and workpiece deflection) and machinability aspects of the workpiece material (favourable chip forms). Nonlinear and linear models, used as constraints, were developed based on the results of experimental investigation of turning of POM-C using a PCD cutting tool. The total operation time estimation model showed good agreement with the results of tool path simulations in CAM software and validation experimental trial in real manufacturing environment. By applying the optimal solution, 44% of the total time being saved for machining of a single part can be achieved, compared to the recommended cutting parameter values, which indicates significant optimization benefits in turning industrial plastics.