TECHNICAL DATA FORMULAS FOR DRILLING y CUTTING SPEED (vc) ) • DC • n (SFM) vc (SFM) : Cutting Speed DC(inch) : Drill Diameter)(3.14): Circular Constantn(min-1) : Rotational Speed of the Main Spindle (Problem) What is the cutting speed when main axis spindle speed is 1350 min-1 n and drill diameter is .500 inch ? (Answer) Substitute )=3.14, DC=.500 inch, n=1350 into the formula vc = ) • DC • n = = 176.6 SFM The answer is 176.6 SFM DC y FEED OF THE MAIN SPINDLE (vf) vf (IPM) : Feed Speed of the Main Spindle (Z axis) (IPM) fr (IPR) : Feed per Revolution n (min-1) : Rotational Speed of the Main Spindle (Problem) What is the spindle feed (v f) when feed per revolution is .008 IPR and vf n main axis spindle speed is 1350 min-1? (Answer) Substitute fr=.008, n=1350 into the formula vf = fr×n = .008×1350 = 10.8 IPM The answer is 10.8 IPM. fr y DRILLING TIME (Tc) Tc (min) : Drilling Time (Problem) What is the drilling time required for drilling a 1.2 inch n (min-1) : Spindle Speed length hole in alloy steel at a cutting speed of 165 SFM ld (inch) : Hole Depth and feed .006 IPR ? fr (IPR) : Feed per Revolution i : Number of Holes (Answer) Spindle Speed n The answer is 11.2 sec. ld P P034 TECHNICAL DATA