MultiSpindle

  1. MultiSpindle
  2. Procunier SFM Chart

Suggested Cutting Speeds with HSS Tools

Material Brinell Drills S.F.M. Taps – S.F.M. Threads Per Inch
3-8 9-15 16-24 25 UP
Aluminum (die cast) 95-105 250 50 100 130 150
Aluminum 95-105 200 50 100 130 150
Bakelite 80 50 100 130 150
Brass 192-202 200 50 100 130 150
Bronze Common 166-183 200 40 80 100 150
Bronze Phos. 1/2 hard 187-202 175 25 40 50 80
Copper 80-85 70 40 80 100 150
Cast Iron – soft 126 140 30 60 90 130
Cast Iron – hard 300 45 10 20 30 40
Cast Iron, Malleable 112-126 85 20 30 40 50
Duralumin 90-104 200 50 100 130 150
Nickel 187-202 75 25 40 50 80
Rubber – hard 100 50 100 150 200
Steel – mild .20-.30C 170-202 115 40 55 70 90
Steel – .40-.50C 170-196 80 20 30 40 50
Steel, Stainless 460-520 20 8 10 15 20
Steel, Tool 241 50 15 15 20 20
Zinc 110-125 200 50 100 130 150

Feeds For High Speed Drills

Drill Diameter Inches
Feed Inch Per Revolution
1/16 to 1/8
.001 – .003
1/8 to 1/4
.002 – .006
1/4 to 1/2
.004 – .010
1/2 to 1"
.007 – .015

Useful Formulas

RPM = 3.82 x SFM
Dia.

SFM = .262 x D x RPM
1 ÷ Pitch = Tap Lead

% of Threads (cut Taps) = Threads per Inch x ( major dia. of tap – drill dia. )
.01299

Example for 1/4-20 tap, using # 7 drill.
.250 – .201 = .049 ÷ .01299 = 3.77 x 20 = 75% thread
Note: Use .0068 divisor for roll form Taps.

Tap Drill Size (cut Taps) = major Dia of tap – ( .01299 x % of full thread )
TPI

Example for 1/4-28 with 70% required Threads.
.01299 x 70 = .909 ÷ 28 = .032
.250 – .032 = .218 drill Size

Tap Drill Size (form Taps) = major Dia tap – ( .0068 x % full thread )
TPI

Example for 1/4-20 tap with 65% required Threads.
.0068 x 65 = .442 ÷ 20 = .022
.250 – .022 = .228 drill Size

Calculation of Tapping cycle time for Procunier tappers.

Inch cycle time (seconds) =
( 90 x TPI x travel )
RPM
MM cycle time (seconds) =
( 2286 x travel )
MM (Pitch) x RPM

Example for 10-32 at 1140 RPM
90 x 32 x .625 ÷ 1140 = 1.6 seconds

Example for M10 x 1.25 at 860 RPM
2286 x .950 = 2171.7
1.25 x 860 = 1075
2171.7 ÷ 1075 = 2. seconds

Notes:
Formulas include 2:1 reverse found on all Procunier tappers. Travel Includes tap clearance above piece part and total depth into hole

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