Study On Dry Milling Performances And Tools Wear Mechanisms Of Ti-6Al-4V

With the continuous progress and development of science and technology,modern manufacturing has put forward new requirements for the processing of parts.Traditional cutting tools are no longer able to meet the current high-precision and high-efficiency needs.The appearance of some high-performance cutting tools have pointed out a new direction for the development of modern manufacturing.Ti-6Al-4V,as one of the most widely used titanium alloys,is difficult to process due to its high chemical activity,strength,cutting temperature,poor thermal conductivity,severe work hardening,and sig-nificant elastic recovery.Therefore,efficient production has always been a highly con-cerned issue.In recent years,researchers have been looking for a suitable cutting tool to strike a better balance between workpiece quality and production cost.Therefore,re-searching the dry milling performance of Ti-6Al-4V and the wear mechanism of its cut-ting tools is essential.This article first tested the basic properties of tool substrate material(W6Mo5Cr4V2Al steel),conventional nitride-coated(AlCrN coating),and self-lubricat-ing coating(DLC coating),such as surface morphology,elemental content,film-substrate adhesion,hardness,and surface roughness.The researchers analyzed their friction and wear characteristics,wear morphology,and wear mechanism under different loads and reciprocating speeds.Then,Ti-6Al-4V was used as the milling object to study the dry milling performance of AlCrN-coated milling tools,DLC-coated milling tools,and ul-trafine-grain hard alloy milling tools.The study clarified the relationship between milling bending moment and energy consumption and milling parameters(a_p,a_e,f,and n),and evaluated the durability of the tools.Finally,the wear morphology and mechanism of the three milling tools after milling with different parameters were analyzed.Based on the above analysis,the following conclusions were drawn:(1)Regarding surface morphology,W6Mo5Cr4V2Al steel has the smoothest surface,while the DLC coating has the roughest surface.Concerning hardness,the AlCrN coating has the highest hardness,followed by the DLC coating,and W6Mo5Cr4V2Al steel has the lowest hardness.In terms of surface roughness,the DLC coating has the greatest sur-face roughness,followed by the AlCrN coating,and W6Mo5Cr4V2Al steel has the least surface roughness.The DLC coating has a higher film-substrate adhesion than the AlCrN coating.Concerning friction coefficient,W6Mo5Cr4V2Al steel has a higher friction co-efficient than the AlCrN coating,and a higher friction coefficient than the DLC coating.Oxidation wear,abrasive wear,and diffusion wear are the main types of wear for W6Mo5Cr4V2Al steel,AlCrN coating,and DLC coating.The DLC coating has an addi-tional type of wear,which is oxide wear.(2)Regarding milling performance,the milling bending moment first decreases and then increases with the increase of spindle speed,with similar effects on the AlCrN and DLC coated milling tools,and the largest effect on the ultrafine grain cemented carbide milling tools.Milling bending moment increases with increasing milling width,with the greatest effect on DLC coated milling tools,followed by AlCrN coated milling tools,and the smallest effect on ultrafine grain cemented carbide milling tools.Milling bending mo-ment increases with increasing milling depth,with the largest effect on AlCrN coated milling tools,followed by ultrafine grain cemented carbide milling tools,and the smallest effect on DLC coated milling tools.Milling bending moment increases with increasing feed rate,with the largest effect on AlCrN coated milling tools,followed by ultrafine grain cemented carbide milling tools,and the smallest effect on DLC coated milling tools.Mill-ing energy consumption increases with the increase of spindle speed,milling width,and milling depth,with the greatest effect on AlCrN coated milling tools,followed by DLC coated milling tools,and the smallest effect on ultrafine grain cemented carbide milling tools.Milling energy consumption decreases with increasing feed rate,with similar ef-fects on the three types of tools.(3)Regarding predicting the milling bending moment and energy consumption mod-els,the AlCrN-coated milling tools’bending moment and energy consumption prediction models have error rates of 9.2%and 5.4%,respectively.DLC-coated milling tools’bend-ing moment and energy consumption prediction models have error rates of 6.2%and 7.5%,respectively.The error rates for predicting the milling bending moment and energy con-sumption models for ultrafine-grained hard alloy milling tools are 2.6%and 4.2%,re-spectively.AlCrN-coated milling tools have a service life of 126 minutes,DLC-coated milling tools have a service life of 181 minutes,while ultrafine-grained hard alloy milling tools have a service life of 242 minutes.(4)Regarding the wear mechanism of milling tools,the AlCrN coating milling tools mainly has bond wear,diffusion wear and oxidation wear,the DLC coating milling tools mainly has bond wear,abrasive wear,diffusion wear and oxidation wear,the ultrafine grain carbide milling tools mainly has bond wear,abrasive wear,diffusion wear and oxi-dation wear.