Case Studies of Diamond-Coated Tool Cutting Simulations: Coating Thickness and Cutting Speed Effects

Due to the interwoven effects in both diamond deposition and subsequent machining processes, the tool geometry and process parameters have compound effects on the thermal and mechanical states in diamond-coated cutting tools during machining. For example, increasing the coating thickness tends to increase deposition-induced residual stresses at the tool edge interface. Further, a thick coating will introduce a greater machining load due to an enlarged edge radius. However, it has not been investigated how the coating thickness affects the thermo-mechanical behaviors of diamond-coated tools during machining. In a previous study, finite-element based simulations were developed to conduct systematic analyses of diamond-coated tool cutting. In this work, the developed 2D cutting simulations that incorporate deposition residual stresses were applied to evaluate the coating thickness and cutting speed effects on the tool stress contours, tool temperatures as well as the interface stresses around a cutting edge. The major findings can be summarized as follows. (1) The coating thickness effect on the first principal stress is minor. A thicker coating can decrease cutting temperature effectively, but increase the thrust force noticeably. Additionally, a thicker coating is also favorable for the reduction of interface radial normal stresses around the cutting edge. (2) For a constant coated tool edge radius, decreasing the substrate edge radius (while increasing the coating thickness) will elevate the maximum first principal stresses but significantly reduce tool temperatures and the interface radial normal stresses. (3) The cutting speed has little effect on the first principal stresses, but strongly affects the cutting tool temperatures. Moreover, the interface radial normal stresses and circumferential stresses decrease with the increase of cutting speed, which is intuitive since higher cutting temperatures associated with a high cutting speed are expected to relieve high deposition stresses.