Study On Burr Formation Mechanism And Tool Wear In CFRP Milling

Carbon fiber reinforced polymer(CFRP)is widely used in aerospace,automobile,ship,sports goods and military fields.It has many excellent properties,including high hardness,fatigue resistance,toughness,high specific strength,high specific modulus and light weight.However,the tool wear is serious during CFRP processing because of the high hardness and special structure of CFRP.In this paper,the side milling experiment of UD-CFRP is carried out with a common end mill.The formation law of surface defects(such as burrs)under different fiber angles is analyzed.Secondly,the cutting force and burr factor during MD-CFRP milling process by using HC-S200 and K44 carbide corn milling cutter are investigated.The results show that K44 cutter is more suitable for CFRP milling.Finally,the tool wear and surface burr factor of corn milling cutter in CFRP milling are analyzed.In addition,the changing rule of tool wear with cutting conditions in CFRP milling is also discussed.This research provides an important theory for the milling process of CFRP.The main research contents are as follows:(1)The experiments of milling UD-CFRP with HC-S200 milling cutter at different fiber orientation angles are carried out.The formation of surface damage during the processing is observed,and the burr formation with cutting parameters and fiber angle is analyzed.The results show that the machined surface of CFRP is serrated when the fiber orientation angle is β=45°.At the same time,it is accompanied by a large number of long burrs,and the surface morphology is the worst.(2)Burr was found to be the main defect on the machined surface.The mechanism of milling CFRP with different fiber orientation angles was analyzed.Moreover,the formula of burr factor is defined based on the study of burr formation mechanism in milling CFRP.(3)The effects of milling parameters on burrs and milling forces during MD-CFRP milling process by HC-S200 conventional carbide milling cutter and K44 carbide corn cutter are analyzed.The prediction formula of cutting force and burr factor is established based on the regression analysis method.The results show that the milling force produced by the two cutters is slightly different with the cutting parameters(spindle speed,feed and radial cutting depth).The variation trend of cutting force increases with the increase of machining parameters.The burr factor of the two milling cutters increases with the increase of cutting parameters.In addition,it is found that K44 corn milling cutter has lower milling force and less surface burr,which is more suitable for CFRP milling.(4)The effect of milling conditions on burr factor and tool wear is studied by K44 corn milling cutter.The results show that burr factor and tool wear are positively correlated with milling conditions,and both increase with spindle speed,feed and cutting length.