Machining Applications Views: 15

Principles and methods for choosing cutting parameters: The three elements - speed (S), feed (F) and depth of cut (ap) - interact and must be balanced. Principles: 1) By material - harder and tougher materials: lower speed, smaller feed; softer materials: higher speed, larger feed; 2) By tool size - larger diameters: lower speed (constant line speed means larger diameter = lower rpm); smaller diameters: higher speed; 3) By machine rigidity - rigid machines can take higher parameters; weak machines need lower ones to avoid vibration; 4) By finish requirements - high finish: smaller feed, moderately higher speed, final light pass; low requirements: higher parameters for efficiency; 5) By batch - production batches: conservative parameters for life and consistency; small jobs/repairs: higher parameters for speed; 6) By tool grade - HSS spins slower, carbide faster, cobalt HSS in between. Selection steps: 1) Line speed (Vc) - reference by material and grade: carbon steel Vc=20-40m/min, stainless 10-20, aluminum 50-100; 2) Calculate rpm - S = 1000 x Vc / (pi x D), D = tool diameter; 3) Feed per tooth (fz) - by material and requirements, generally 0.03-0.15mm/tooth; 4) Feed rate - F = S x z x fz, z = flutes; 5) Trial cut - test with calculated values, observe cutting, finish and wear, adjust; 6) Optimize - fine-tune to find the best. Reference (cobalt HSS-E): 1) carbon steel - 800-1500rpm, feed 0.1-0.2mm/rev; 2) stainless - 400-800rpm, 0.05-0.1mm/rev; 3) aluminum - 1500-3000rpm, 0.15-0.3mm/rev; 4) mold steel - 500-1000rpm, 0.06-0.12mm/rev; 5) superalloys - 200-400rpm, 0.03-0.06mm/rev. Adjustment tips: 1) fast wear - lower speed, smaller feed, better grade or coating; 2) poor finish - smaller feed, higher speed, final pass, check runout; 3) vibration - lower speed, smaller feed, shorter overhang, more rigidity; 4) welding - change speed (avoid BUE range), add fluid, coated tools; 5) low efficiency - raise speed and feed while keeping quality and life. Parameters are not fixed - adjust by reality, trial-cut and summarize to find your optimum. Ask our technical team for parameter recommendations.