鋁基複合材料切削加工特性之研究

Abstract

本研究主要是探討銑削不同比例之Al2O3強化顆粒鋁基複合材料之切削性，並比較奈米切削液和水基切削液在濕切削與最少量潤滑 (Minimun quantity lubrication, MQL)下切削鋁基複合材料之影響。文中以刀具磨耗，工件表面粗糙度，切削力與切屑來分析鋁基複合材料之切削性。研究結果顯示使用鍍層碳化鎢刀具乾切削10 wt.% Al2O3鋁基複合材料刀具幾無磨耗，但容易在刀面產生刃口積屑(Built-up edge, BUE)，而添加奈米微量噴霧可改善刃口積屑之問題，奈米顆粒扮演著固態潤滑層的角色，撐開切屑與刀面，使切屑不易黏在刀面，大幅改善表面粗糙度。使用鍍層碳化鎢刀具乾切削15 wt.% Al2O3鋁基複合材料刀面刃口積屑減少，而刀具開始產生嚴重刀具磨耗，使用奈米微量潤滑可得較好表面粗糙度與降低刀腹磨耗，但是效果與濕切削十分相近。切削20 wt.% Al2O3鋁基複合材料，鍍層碳化鎢刀具無法承受強化顆粒的磨耗，而使用多晶鑽石刀具(Polycrystalline diamond tool, PCD)在乾切削下可以克服刀腹磨耗問題，但是在濕切削下會造成PCD刀具發生微崩落(Micro chipping)使表面粗糙度變差，採用微量噴霧不會產生微崩落，刀腹磨耗與表面粗糙度與乾切削相近。因此欲切削10 wt.% Al2O3和15 wt.% Al2O3鋁基複合材料時，使用一般之鍍層碳化鎢刀具搭配奈米微量噴霧，即可得到很好的效果，而切削20 wt.% Al2O3鋁基複合材料時則可選用PCD刀具以乾切削之方式切削。

An experimental investigation on the end milling of aluminum based metal matrix composites with different percentage of Al2O3 particles was conducted in this study. The machinability in terms of tool wear, surface roughness, cutting force and chip morphology was studied under different cutting settings including dry cutting, wet cutting and minimum quantity lubrication with nano fluid and the water-based fluid. The results show that flank wear occurs in dry cutting of 10 wt.% Al2O3 aluminum metal matrix, It will cause serious built-up edge, but it can be reduced by using minimum quantity lubrication with nano. The nano particles can generate a solid lubricant layer between the tool face and chips. Hence chip sticking on tool face is reduced and the surface roughness is improved. The cutting of 15 wt.% Al2O3 aluminum metal matrix causes fewer built-up edge but more serious flank wear than that of 10 wt.% Al2O3 aluminum metal matrix. Using minimum quantity lubrication with nano fluid can improve tool life and surface roughness in cutting of 15 wt.% Al2O3 aluminum metal matrix. However, the effect is the same as that of wet cutting. Using the polycrystalline diamond tool can improve flank wear under dry cutting, but micro chipping will occur in wet cutting. It is effective in cutting 10 wt.% Al2O3 and 15 wt.% Al2O3 aluminum metal matrix composites with coated carbide tool by using MQL with nano fluid, but PCD tool is better in cutting 20 wt.% Al2O3 aluminum metal matrix composites under dry cutting condition.