鋁基複合材料高速切削加工特性之研究

Abstract

High speed milling of various proportions Al2O3 particles reinforced aluminum-based metal matrix composites (MMCs) under different cutting fluid application conditions is presented in this study. It is found that the built up edge (BUE) which influent the machined surface finish is easily formed in machining of Al2O3 aluminum MMCs. Hence a very high cutting speed together with MQL is recommended to cut this type of MMCs. The flank wear of the cutting tool, machined surface roughness, cutting force and chip formation are investigated during the experiment. The results show that nearly no flank wear occurs but BUE forms easily in machining of 10 wt.% Al2O3 aluminum MMCs, which becomes much fewer as the cutting speed increases. The machining under wet cutting and MQL (minimum quantity lubrication) can significantly reduce BUE to achieve a better surface finish besides lowering cutting force. High speed dry milling of 15 wt.% Al2O3 aluminum MMCs generates few BUE but accompanied with accelerated flank wear with the increasing cutting speed. A better machined surface finish and an increased tool life than those under dry cutting and wet cutting are observed when MQL is applied as the permeation of the oil mist is more effective. On the contrary, the wear n the machining of 20 wt.% Al2O3 aluminum MMCs is so serious that there is little improvement in tool wear and surface finish under MQL condition. In summary, high cutting speed with the aid of MQL is appropriate in machining 10 wt.% and 15 wt.% Al2O3 aluminum MMCs for smaller tool wear and better surface finish as the cutting speed is up to 500 m/min. High speed machining is not suggested in machining of aluminum MMCs with higher content of reinforced particles such as 20 wt.% due to the serious tool wear. Cutting speed that lower than 200 m/min with MQL applied is appropriated in machining of 20 wt.% Al2O3 aluminum MMCs.