TG_SFC_US-EN

ALLIED MACHINE & ENGINEERING | RECOMMENDED CUTTING DATA

Thread Mill Pre-Drill Information

Formula

Metric

Imperial

Velocity

M/min = RPM • 0.003 • CuƩer Diameter

SFM = RPM • 0.262 • CuƩer Diameter

(M/min • 318.47) CuƩer Diameter

(SFM • 3.82) CuƩer Diameter

RPM =

Speed

RPM =

Linear Feed Rate (LFR)

mm/min = RPM • (mm/tooth • Number of Flutes)

IPM = RPM • (IPT • Number of Flutes)

(Major Diameter - CuƩer Diameter) Major Diameter

Adjusted Feed Rate (AFR) See Note Below

AFR =

• LFR

NOTE: The above formula on an internal thread program adjusts the linear feed rate to be applied to the outer diameter instead of the center of the cuƫng tool. If the feed rate is not adjusted, the excessive feed rate will cause the thread mill cuƫng edges to fail.

Example of an Internal Adjusted Feed Rate Calculation:

Free machining steel at 125 BHN with a M16x2 2B thread using ThreadMills USA ™ solid carbide thread mill (TM16200) running at 221 M/min and 0.038 mm/tooth

(M/min • 318.47) CuƩer Diameter

(221 • 318.47) 11.94

RPM =

RPM =

STEP 1:

RPM = 5895

STEP 2:

LFR = RPM • (mm/tooth • Number of flutes)

LFR = 5895 • (0.038 • 4)

LFR = 896.04 mm/min

(Major Diameter - CuƩer Diameter) Major Diameter

(16.00 - 11.94) 16.00

AFR =

• 896.04

AFR =

• LFR

STEP 3:

AFR = 227.37 mm/min

Unit Definitions

M/min = Meters per Minute SFM = Surface Feet per Minute

Velocity

RPM = RevoluƟons per Minute

Speed

mm/rev = millimeters per revoluƟon mm/tooth = millimeters per tooth also known as millimeters per flute IPR = Inch per RevoluƟon IPT = Inch per Tooth also known as Inch per Flute mm/min = millimeters per minute IPM = Inches per minute

Feed

173

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