Abstract:

As a typical difficult-to-machine material, AISI 316L austenitic stainless steel has the problems of low machining efficiency and large thermo-mechanical load during machining. The present methods to improve the machining performance of stainless steel such as adopting lubrication, designing tool surface structure, etc., all exist obvious defects. For example, the extensive use of cutting fluid is detrimental to the environment and human health, and tool wear will be aggravated if the tool surface structure is designed unreasonably. Given that the existing methods fail to well deal with the problems like large thermo-mechanical load during machining austenitic stainless steel, a new restricted contact tool with variable contact length was designed aiming at machining AISI 316L auste-nitic stainless steel. Compared with traditional restricted contact tools, the new tool is superior in reducing cutting force and friction coefficient. This paper first developed a semi-analytical model for turning to predict cutting forces for inconstant restricted contact length based on the non-equidistant shear zone model and the principles of unified cutting mechanics. Then, the conventional and variable-length restricted contact pattern (rectangular and trapezoidal restricted contact pattern) was fabricated on the rake surface of uncoated cemented carbide by the W-EDM and micro-EDM process. Subsequently, extensive experiments were performed to validate the proposed model. Results show that the cutting forces predicted by the proposed semi-analytical model are in good agreement with the experimental values. As compared with conventional restricted contact tools, the developed restricted contact tool can significantly reduce cutting forces. Furthermore, the influences of conventional and developed restricted contact tools on cutting performance were compared and analyzed under dry machining conditions. The restricted contact tool developed in this paper can effectively decrease the cutting temperature and tool wear. This study can provide a basis for designing the cutting tools in machining difficult-to-cut materials.

Key words: cutting, restricted contact tool, variable contact length, semi-analytical model, cutting performance, AISI 316L austenitic stainless steel