Optimization of the cutting mechanism in die steel milling using textured NCD-coated tools and vortex tube cooling

In traditional milling of die steel, the harsh conditions, characterized by high temperature and high pressure in the cutting area, often result in excessive tool wear and poor workpiece surface quality. Textured tools coated with nanocrystalline diamond (NCD) have demonstrated significant improvements in cutting performance, while vortex tube cold air technology further optimizes the cutting conditions. This study applies NCD coatings to the surface of snowflake bionic textured tools, followed by milling tests combined with vortex tube cooling. The results demonstrate that machining with vortex tube cooling effectively reduces cutting temperature and enhances the thermal load conditions in the cutting zone. Specifically, milling temperature decreased by approximately 32.65 %, and the maximum reduction in workpiece surface roughness reached 58.76 %. Additionally, the texture on the tool surface substantially mitigates cutting heat generation, optimizes lubrication conditions, and reduces cutting force and friction coefficient, resulting in a significant reduction in tool wear and a 12.46 % decrease in milling force. • Snowflake-inspired surface textures were designed and their anti-friction mechanisms analyzed. • NCD coatings were synthesized via HFCVD, characterized, and experimentally assessed. • The velocity and temperature fields of the cryogenic jet were modeled to optimize device configuration. • Cutting performance and tribological behavior were evaluated using textured, NCD-coated tools under cryogenic conditions.