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Speed & Feed Charts

Gun Drill, Half Round Drill, TWINMASTERTWINMASTER™ - Registered Trademark of Sterling Gun Drills Twin Flute Drill

RPM=SFM ÷ 0.262 ÷ DRILL DIA.


Speed and Feed assumes proper bushings, supports, oil type, pressure, and general machine condition is acceptable. Use as a starting reference only!

High Pressure (SFM Chart Column) refers to a gun drill machine or the equivalent pressure. Spraymist (S/mist) refers to our DM2000 / DM3000 kits, or high "EP" coolant at no less than one third gun drill machine pressure for the diameter.

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TOOL STEELS
D,S,M,O,H,P Series Hi Pressure
Rc SFM
17-22 250
22-27 200
27-32 150
32-37 100
 
ALLOY STEELS
4000, 5000, 8000 Series  
Rc SFM
17-22 300
22-27 250
27-32 200
32-37 150
37-42 100
 
Low to Med. CARBON STEEL
C1010-1550
Rc SFM
12-17 400
17-22 350
22-27 300
27-32 250
32-37 200
37-42 150
 
STAINLESS STEEL* 300 Series
300 Series & PH
Rc SFM
12-17 230
17-22 200
22-27 170
27-32 140
32-37 110
37-42 80
Free Machining + 30%
 
STAINLESS STEEL *  400 Series
400 Series
Rc SFM
12-17 280
17-22 240
22-27 200
27-32 160
32-37 120
37-42 80
Free Machining + 30%
 
CAST IRON
Grey
Rc SFM
12-17 400
17-22 350
22-27 300
27-32 250
With Free Carbides -50%
Ni-Resist -60%
 
CAST IRON
Ductile, Nodular
Rc SFM
12-17 300
17-22 250
22-27 200
27-32 150
32-37 100
Ductile, Ni-Resist -50%
 
TITANIUM*
6A1 4V, Some Others
Rc SFM
12-17 260
17-22 220
22-27 180
27-32 140
32-37 100
37-42 60
 
HIGH TEMP. ALLOYS*
Nickel Based  
Rc SFM
12-22 120
22-32 90
32-42 60
Cobalt Base -40%
Iron Base +20%
 
COPPER ALLOYS*
Berryllium, Ni-Based  
Rc SFM
12-22 200
22-32 130
32-37 60
 
SOFT ALLOYS Non Ferrous
Aluminum, Copper, Free Brass, Magnesium 500 - 600 SFM
All Conditions
 
  • Consult Sterling Gun Drills to verify application requirements.
  • High SFM will cause vibration and/or harmonics with long gun drills. Reduce RPM or ensure adequate supports are in place or use an intermediate length gun drill.
  • Minimum oil/coolant pressure is 35% of the PSI values on page 2. If at minimum, reduce SFM by 35%.
  • Applications suitable for our Spraymist System, reduce SFM by 35% at same feed rate listed.
  • Water soluble coolant must be oil based, high “EP” at 10-12% concentration, NO SYNTHETICS!

Call for Technical & Engineering Support

Approximate Feed Rate (IN./REV.)

Gun Drills on gundrilling machines, also with spraymist @ 100 + psi, or high pressure, high "EP" coolant. Half Round drills on spraymist, increase feed by 25%.
For TWINMASTER™ Twin Flute drills, high pressure or spraymist, increase feed by 50 - 100%.

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Dia.
(inch)		 Steels
Low, Med.
Carbon		 Steels,
Alloy,
Tool,
Fe Stainless		 Ni Stainless
Titanium,
High Temp.
 Cast Iron,
Grey,
Free cut Alum.		 Cast Iron,
Ductile,
Nodular		 Poor Chipping
Alum. 6061 ex.
Copper
<.055"* .00005" .00005" .00005" .00007" .00007" .00005"
.062"* .00006" .0006" .00006" .00080" .00008" .00006"
.078" .00008" .00008" .00007" .0001" .0001" .00007"
.094" .0001" .0001" .00008" .00015" .00015" .00008"
.125" .00015" .00015" .0001" .0002" .0002" .0001"
.187" .003" .0003" .0002" .0004" .0003" .0002"
.250" .00045" .00045" .0003" .0008" .0006" .0003"
.375" .0007" .0006" .0005" .0015" .001" .0005"
.500" .0008" .0007" .0006" .002" .0015" .0007"
.625" .001" .0009" .0007" .0025" .002" .0009"
.750" .0013" .0011" .0008" .003" .0025" .0011"
1.00" .0016" .0013" .001" .0035" .003" .0015"
1.25" .0018" .0015" .0012" .004" .0035" .0018"
1.50" .002" .0018" .0014" .005" .004" .002"
*Solid carbide flute & tip.
Drill lengths over 50:1, reduce feed rate by 20%.





Oil Pressure, GPM, Unsupported Drill Length

Gun Drill Machine
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Diameter
(inches) 		Oil Pressure
(PSI) 		GPM Max. Unsupported Length
(per spindle) High SFM Low SFM
<.055"* 2500 .20 N/A N/A
.062"* 2000 .25 N/A N/A
.078" 1800 .35 3" 5"
.094" 1500 .50 4" 6"
.125" 1500 .90 5" 8"
.187" 1150 1.60 6" 12"
.250" 925 2.50 8" 16"
.375" 675 4.50 12" 24"
.500" 525 7.00 16" 32"
.625" 450 10.0 20" 40"
.750" 400 14.0 24" 48"
1.00" 300 20.0 32" 56"
1.25" 250 28.0 40" 64"
1.50" 200 36.0 48" 72"
  • Minimum oil/coolant pressure is 35% of the PSI values. If at minimum, reduce SFM by 35%.
  • Water soluble coolant must be oil based, high “EP” at 10-12% concentration, NO SYNTHETICS!
  • * Solid carbide flute & tip