Material Machining Views: 7

Differences when machining different plastics and tool selection: Common characteristics: low melting point, melts and welds easily, low hardness, deforms easily, poor thermal conductivity. But grades differ greatly: 1) ABS - the most common engineering plastic: medium strength, good machinability, less welding, melt point about 105C. Use cobalt HSS or carbide single-flute, high speed 2000-4000rpm, feed 0.1-0.2mm/rev, compressed-air cooling; no cutting fluid (some fluids corrode ABS). 2) PC (polycarbonate) - transparent, strong, tough, melt point about 150C, tacky and welds easily, internal stress can cause cracking. Use carbide single-flute (sharp, low force), high speed 2500-4500rpm, small feed 0.08-0.15mm/rev, air cooling; anneal after machining to relieve stress; very sharp tools. 3) Nylon (PA6, PA66) - tough, wear-resistant, melt point about 220C, tacky, welds easily, elastic and deflects. Use cobalt HSS or carbide + DLC, high speed 2000-4000rpm, feed 0.1-0.2mm/rev, light fluid cooling OK; light clamping to prevent deformation; measure after spring-back. 4) Acrylic (PMMA) - transparent, brittle, melt point about 120C, the easiest to melt, weld and chip; cracks and whitening. Use carbide single-flute (very sharp), high speed 3000-5000rpm, very small feed 0.05-0.1mm/rev, generous air cooling; cut from solid toward the edge; dull tools cause whitening and cracks. 5) POM (acetal) - strong, rigid, wear-resistant, melt point about 175C, good machinability, less welding - machinelike behavior. Use cobalt HSS or carbide, high speed 2000-4000rpm, feed 0.1-0.2mm/rev, dry or air-cooled. Summary: acrylic melts and chips most easily - be careful; PC and nylon are tacky and weld; ABS and POM machine well. Universal rules for plastics: single-flute, high speed, small feed, compressed-air cooling, sharp tools, prevent melting and deformation.