Theoretical And Experimental Research On High Speed Milling SiCp/Al-MMC By PCD Tools

SiCp/Al composite is a widely used hard-to-machine material in the aerospace andelectronics sectors. SiCp/Al composite has high ratio strength and stiffness, fatigueresistance, corrosion resistance, abrasion resistance, low density, low thermal expansioncoefficient and good dimensional stability and thermal conductivity, and many otherexcellent mechanical and physical properties. However, the presentence of SiCreinforcement particles in SiCp/Al composite results in problems such as serious tool wear,poor surface quality, etc. In this thesis, both experimental and theoretical analysis on toolwear, surface quality and milling force are performed based on the fundamentalexperimental studies of high-speed milling of SiCp/Al composite with PCD tools. The worklays the practical and experimental foundations for the establish of high-speed milling ofSiCp/Al composite narrow groove.The main conclusions of the thesis are as follows:1. From the angle of the material characteristics, the defects produced during themachining of SiCp/Al composite is analyzed based on the dislocation theory.Corresponding models are proposed for the removal of three materials in milling process:the dislocation slip in aluminum body wrapped enhanced particles, the shear fracture orbroken in SiC particles, the flaking or pressed into the parts surface in SiC particles.2. The most important reasons of surface defects of SiCp/Al composite material arethe extraction of SiC particles and peel off of diamond particles in PCD tools. Three majorsurface defects of the SiCp/Al composite are verified by SEM analysis: secondary tillages,pits and projections.3. Tools with small amount of runout have long tool life; the tool life can be prolongedto some extent with the existence of small helix angle; a small particle size PCD tool life islonger than a large particle size PCD tool life; a large tool corner radius yields a longer toollife than a small tool corner radius.4. PCD cutting tool wear patterns, including broken at the tip and the main andsecondary flank uneven wear, in which the abrasive wear of secondary flank is the mostimportant reason for PCD tools to reach their blunt standard. In addition, the built-up-edge produced during milling process has a protective effect on the rake face.5. The most significant factor of the milling force is the milling depth, followed by thefeed rate, and finally cutting speed. A moderate milling speed, feed rate, and milling depthshould be chosen if one only considers the magnitude of milling force. This thesis alsoestablishes an empirical formula for3-axis milling force and milling parameters. Theinteractions between the milling parameters are analyzed. As a result, one can use theempirical regression equation to predict the3-axis PCD milling force during the milling ofSiCp/Al composite.