I.INTRODUCTION
The dynamic material model (DMM) method has been widely used for the macroscopic description of flow, fracture, and workability of materials under hot deformation. This inves-tigation is aimed at proposing a new methodology for the optimization of hot machinability of a material using the DMM stability criteria. The constitutive ?ow behavior of Al-20 pct SiC has been evaluated in the temperature range 50 C to 350 C and the cutting velocity in the range from 25 and 300 m/min with the view to optimizing its machinability using the DMM instability parameters. The DMM instability parameters predicted a narrow region around 150 C and 150 m/min as the optimum domain for machining this material. It has been observed that the tool wear is minimum at optimal conditions. This investigation proved that the machinability could be optimized through the DMM.
THE aluminum-based composites are finding increased applications among the various types of metal matrix composites (MMCs). They are being considered as a material for cylinder block liners, vehicle drive shafts, pistons in automobiles, and bicycle frames. Machining is one of the common practices followed in industries for the production of components made of MMC material. The presence of reinforcement particles in the MMC leads to rapid wear of cutting tools during machining by conventional methods. Low cutting speeds are being adopted due to high wear rate results in a high machining cost. Therefore, there is a need to enhance the machining performance for these materials. The enhancement of machining performance should lead to an increased material removal rate, prolonged tool life, and improved surface finish. Machining at elevated temperatures has been considered as a viable approach to achieve these goals. It has been experimentally demonstrated that heating the workpiece can extend the tool life and also improve the roughness of the machined surfaces. Vedani and Garibold reported that at temperatures above 300 C, Al-SiC composites exhibit significantly reduced flow stress. Although the preceding studies have not necessarily been performed under optimal conditions, significant improvement of machinability has been reported. If the parameters such as temperature, depth of cut, and cutting speed are optimized, improvements in machinability can be potentially achievable.
