Thread Milling Product Catalog

THREADING

Thread Mill Pre-Drill Information

Formula

Metric

Imperial

Velocity

m/min = RPM • 0.003 • Cutter Diameter

SFM = RPM • 0.262 • Cutter Diameter

(m/min • 318.47) Cutter Diameter

(SFM • 3.82) Cutter Diameter

RPM =

RPM =

Speed

Linear Feed Rate (LFR)

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

IPM = RPM • (IPT • Number of Flutes)

Adjusted Feed Rate (AFR) See Note Below

(Major Diameter - Cutter Diameter) Major Diameter

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 cutting tool. If the feed rate is not adjusted, the excessive feed rate will cause the thread mill cutting 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) Cutter Diameter

(221 • 318.47) 11.94

RPM =

STEP 1:

RPM =

RPM = 5895

STEP 2:

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

LFR = 5895 • (0.038 • 4)

LFR = 896.04 mm/min

(Major Diameter - Cutter Diameter) Major Diameter

(16.00 - 11.94) 16.00

STEP 3: AFR =

AFR = 227.37 mm/min

• 896.04

• LFR AFR =

Unit Definitions

m/min = meters per minute SFM = surface feet per minute

Velocity

RPM = revolutions per minute

Speed

mm/rev = millimeters per revolution mm/tooth = millimeters per tooth also known as millimeters per flute IPR = inch per revolution IPT = inch per tooth also known as inch per flute mm/min = millimeters per minute IPM = inches per minute

Feed

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