GRINDING FEEDS AND SPEEDS Machinery's Handbook, 31st Edition
1270
Terms and Definitions
a a = depth of cut a r = radial depth of cut, mm C = fraction of grinding wheel width CEL = cutting edge length, mm C U = Taylor constant D = wheel diameter, mm DIST = grinding distance, mm d w = work diameter, mm ECT = equivalent chip thickness = f ( a r , V , V w , f s ), mm = 1 ÷ ( V ÷ V w ÷ a r + 1 ÷ f s ) = V V f a 1 w s r + ^ h = approximately V w 3 a r ÷ V = SMRR ÷ V ÷ 1000 = z 3 f z 3 a r 3 a a ÷ CEL ÷ ( π D ) mm F R = feed rate, mm/min = f s 3 RPM w for cylindrical grinding = f i 3 RPM w for plunge (in-feed) grinding f i = in-feed in plunge grinding, mm/rev of work
f s = side feed or engaged wheel width in cylindrical grinding = C 3 Width = a a approximately equal to the cutting edge length CEL Grinding ratio = MRR ÷ W* = SMRR 3 T ÷ W* = 1000 3 ECT 3 V 3 T ÷ W* MRR = metal removal rate = SMRR 3 T = 1000 3 f s 3 a r 3 V w mm 3 /min SMRR = specific metal removal rate obtained by dividing MRR by the engaged wheel width ( C 3 Width ) = 1000 3 a r 3 V w mm 3 /mm width/min Note: 100 mm 3 /mm/min = 0.155 in 3 /in/min, and 1 in 3 /in/min = 645.16 mm 3 /mm/min T, T U = wheel-life = Grinding ratio 3 W ÷ (1000 3 ECT 3 V ) minutes t c = grinding time per pass = DIST ÷ F R min = DIST ÷ F R + t sp (min) when spark-out time is included = # Strokes 3 ( DIST ÷ F R + t sp ) (min) when spark-out time and strokes are included t sp = spark-out time, minutes V, V U = wheel speed, m/min V w , V wU = work speed = SMRR ÷ 1000 ÷ a r m/min W* = volume wheel wear, mm 3 Width = wheel width (mm)
RPM = wheel speed = 1000 3 V ÷ D ÷ π rpm RPM w = work speed = 1000 3 V w ÷ D w ÷ π rpm
Relative Grindability.— An overview of grindability of the data base, which must be based on a constant wheel wear rate, or wheel-life, is demonstrated using 10 minutes wheel-life shown in Table 2.
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