Page 201 - Parlec Catalog

Technical Information

Tapping Torque Requirements & Speeds 199

TAPPING SPEEDS
Material Tapping Speed (SFM) RPM = 3.82 x SFM
Aluminum 90 - 110
Brass 80 - 100 Tap Diameter
Bronze 40 - 60
Copper 70 - 90
Copper-Beryllium 40 - 50 FEED (IPR) = 1
Inconel, Hastalloy, Waspalloy 5 - 15 Pitch
Iron-Cast 65 - 75
Iron-Malleable 30 - 60
Magnesium 90 - 110
Plastics 60 - 90 FEED (IPM) = Feed (IPR) x Speed (RPM)
Steel-Cast 30 - 40
Steel-Free Machining 50 - 80
Steel-Chromium 25 - 40
Steel-Alloy 20 - 35
Steel-Stainless 15 - 30 Tapping speeds are for general purpose taps. Consult
Titanium 10 - 25 tap manufacturer for high geometry taps.
Zinc-Die Cast 80 - 120

TORQUE REQUIREMENTS
Aluminum and Approximate
Tap Size Brass Leaded Brass 200 BHN Steel 300 BHN Steel 400 BHN Steel Breaking Torque
#6 4 2 7 9 10 8
#8 4.5 2.25 8 10 11 30
#10 8.5 4.25 15 19 21 42
1/4 16 8 28 36 40 106
5/16 24 12 42 54 60 180
3/8 37 18.50 65 83 93 240
7/16 54 27 94.5 122 135 500
1/2 68 34 119 153 170 700
9/16 88 44 154 198 220 850
5/8 119 59.50 208 268 298 1000
3/4 170 85 298 383 425 1500
7/8 238 119 416 536 595 2100
1 337 168.50 590 758 842 2700
1 1/4 544 277 970 1246 1385 3000+
1 1/2 850 425 1488 1912 2125 3000+
1 3/4 1411 706 2471 3177 3530 3000+
2 1904 952 3332 4284 4760 3000+
2 1/4 2159 1080 3780 4860 5400 3000+
2 1/2 2975 1488 5208 6996 7440 3000+
2 - 8 533 267 933 1199 1333 3000+
2 1/2 - 8 663 332 1160 1492 1658 3000+
3 - 8 1139 570 1995 2565 2850 3000+
4 - 8 1411 706 2471 3177 3530 3000+
5 - 8 1768 884 3094 3978 4420 3000+
6 - 8 2125 1063 3720 4784 5315 3000+
All values in table above are in inch/Ibs. Approximate values based on sharp, 4 Flute coarse pitch hand taps at 65% thread height. Dull taps require approximately 50% more torque. For 55%
and 75% thread heights, multiply above values by .75 and 1.25 respectively. Torque values for helical flute taps are approximately 70% of those shown. Torque values for chip drive taps are
approximately 60% of those shown. Torque values for fine pitch threads are approximately 50% of those shown.

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