Machinery's Handbook, 31st Edition
1152
Machining Power Table 7. Chisel Edge Factors for Torque and Thrust
Torque Factor A 1.000 1.005 1.015 1.020 1.040 1.080
Thrust Factor B 1.100 1.140 1.200 1.235 1.270 1.310
Thrust Factor J
Torque Factor A 1.085 1.105 1.155 1.235 1.310 1.395
Thrust Factor B 1.355 1.380 1.445 1.500 1.575 1.620
Thrust Factor J 0.030 0.040 0.065 0.090 0.120 0.160
Approx. w / d
Approx. w / d
c / d
c / d
0.03 0.025 0.05 0.045 0.08 0.070 0.10 0.085
0.001 0.18 0.155 0.003 0.20 0.175 0.006 0.25 0.220 0.010 0.30 0.260 0.017 0.35 0.300 0.022 0.40 0.350
0.13
0.110
0.15 0.130
For drills of standard design, use c / d = 0.18; for split-point drills, use c / d = 0.03 c / d = Length of Chisel Edge ÷ Drill Diameter. w / d = Web Thickness at Drill Point ÷ Drill Diameter. For inch units only:
2 JW
(1) (2) (3) (4) (5) (6)
T = 2 K d F f F T BW + K d D
M = K d F f F M AW P c = MN ⁄63,025 T = 0.05 K d F f F T BW + 0.007 K d D
For SI metric units only:
2 JW
, K FF AW 40 000 d f M
M =
= 0.000025 K d F f F M AW
P c = MN ⁄9550
Use with either inch or metric units:
P E P m c =
(7)
where P c = Power at the cutter; hp, or kW
P m = Power at the motor; hp, or kW
M = Torque; in. lb, or N.m T = Thrust; lb, or N K d = Work material factor (See Table 6) F f = Feed factor (See Table 8)
F T = Thrust factor for drill diameter (See Table 9) F M = Torque factor for drill diameter (See Table 9) A = Chisel edge factor for torque (See Table 7) B = Chisel edge factor for thrust (See Table 7) J = Chisel edge factor for thrust (See Table 7) W = Tool wear factor (See Table 3) N = Spindle speed; rpm E = Machine tool efficiency factor (See Table 4) D = Drill diameter; in., or mm c = Chisel edge length; in., or mm (See Table 7) w = Web thickness at drill point; in., or mm (See Table 7) Example: A standard 7 ∕
8 inch drill is to drill steel parts having a hardness of 200 BHN on a drilling machine having an efficiency of 0.80. The spindle speed to be used is 350 rpm and the feed rate will be 0.008 in/rev. Calculate the thrust, torque, and power required to drill these holes: K d = 24,000 (From Table 6) F f = 0.021 (From Table 8) F T = 0.899 (From Table 9) F M = 0.786 (From Table 9) A = 1.085 (From Table 7) B = 1.355 (From Table 7) J = 0.030 (From Table 7)
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