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FORMULAS FOR MILLING

CUTTING SPEED (vc) vc (SFM):Cutting Speed D1 (inch):Cutter Diameter π (3.14):Pi n (min-1):Main Axis Spindle Speed Check the item you want to calculate, input values in the two boxes, and then press the Calculate button. D (inch) n (min-1) vc (Problem) : What is the cutting speed when main axis spindle speed is 350min-1 and cutter diameter is φ5" ? (Answer): Substitute π3.14, D=5", n=350 into the formulae. vc =π×D×n÷12=3.14×5"×350÷12= 457.9SFM The cutting speed is 457.9SFM.

FEED PER TOOTH (fz) fz (IPT):Feed per Tooth z:Insert Number vf (inch/min):Table Feed per Min. n (min-1):Main Axis Spindle Speed(Feed per Revolution fr=zxfz) Check the item you want to calculate, input values in the three boxes, and then press the Calculate button. vf (inch/min) z n (min-1) fz (Problem) : What is the feed per tooth when the main axis spindle speed is 500min-1, insert number is 10, and table feed is 20inch/min ? (Answer): Substitute the above figures into the formulae. fz =Vf÷(z×n)=20÷(10×500) = .004IPT The answer is .004IPT.

TABLE FEED (vf) vf (inch/min):Table Feed per Min. fz (IPT):Feed per Tooth z:Insert Number n (min-1):Main Axis Spindle Speed Input the values fz z n(min-1) vf (Problem) : What is the table feed when feed per tooth is .004IPT, insert number is 10, and main axis spindle speed is 500min-1? (Answer): Substitute the above figures into the formulae. vf = fz×z×n = .004IPT×10×500 = 20inch/min The table feed is 20inch/min.

CUTTING TIME (Tc) Tc (min):Cutting Time vf (inch/min):Table Feed per Min. L (inch):Total Table Feed Length (Workpiece Length: l+Cutter Diameter:D1) Input the values L (inch) vf (inch/min) Tc (min) second (s) (Problem) : What is the cutting time required for finishing 4" width and 12" length surface of a cast iron (GG20) block when cutter diameter is φ4", the number of inserts is 16, the cutting speed is 410SFM , and feed per tooth is .01. (spindle speed is 200min-1) (Answer): Calculate table feed per min vf=.01×16×200=32inch/min Calculate total table feed length. L=12+4=8inch Substitute the above answers into the formulae. Tc =16÷32= 0.5(min) The answer is 30 sec.