Analysis of critical negative rake angle and friction characteristics in orthogonal cutting of AL1060 and T2

Abstract

The stagnant region often appears in front of the tool cutting edge, which is caused by mechanical inlay and excessive pressing in plastic metal cutting with large negative rake angle tools at a low speed. It results in the change of the effective negative rake angle which can affect the flow characteristics of material, the quality of machined surface and the abrasion loss of cutting tools. However, the critical negative rake angle model based on the existence of the stagnant region has not been reported yet. Therefore, in order to investigate the critical negative rake angle value considering the stagnant region, a critical negative rake angle model based on the principle of minimum required energy is established, and the correctness of the theoretical model is verified by orthogonal cutting experiments. At the same time, the influence of the critical value of the large negative rake angle tool on the machined surface quality is studied through different cutting experiments. These experimental results show that the deviations of both experimental and theoretical critical negative rake angle are less than 5% during the orthogonally cutting of the aluminium (AL1060) and copper (T2) materials by the negative rake angle tool. Meanwhile, the critical negative rake angle is related to the adhesive friction coefficient of tool–workpiece contact surface. The analysis of friction characteristics shows that the deviation values of both theoretical and experimental critical negative rake angle are proportional to the coefficient of adhesive friction and the thickness of the stagnant region. Critical negative rake angle has a significant effect on roughness and residual stress of the machined surface.

Edge Effect Analysis on orthogonal cutting the Plastic Metal Material-C10100 with Negative Rake Angle Tool

“…This stagnant region is wrapped around the rounded-edge tool blade, which acts as the tool true surface. The simulation results are consistent with those obtained by the scholar Ohbuchi Y and Ding [6,11]. And the stagnant region change the flow characteristics of the material, meanly some materials flow up along the stagnant region to form chips at the speed of v1, and some materials flow down along the stagnant region to form the processed surface at the speed of v2.…”

Friction behaviors in the metal cutting process: state of the art and future perspectives

“…Similar findings were obtained in which the interfacial friction force with a rake angle of 0 • was less than that with a rake angle of 20 • [109]. In addition, the critical negative rake angle was associated with the adhesive friction coefficient at the toolworkpiece interface [111]. The average friction coefficient increased and remained constant as the critical negative rake angle increased.…”

Experimental Study on the Minimum Undeformed Chip Thickness Based on Effective Rake Angle in Micro Milling

“…Then, he also found the minimum negative rake angle is −65° in nanometric cutting of copper material [ 25 ]. Ding et al [ 26 ] found that the minimum negative rake angle is −77° in orthogonal cutting of AL 1060. Lai et al [ 27 ] reported that the minimum negative rake angle for chip formation of copper is between −65° and −70°.…”