A25-TAP_US-EN

DRILLING | T-A Pro® High Penetration Replaceable Insert Drilling System

Tap Drill Information and Formulas | Imperial (inch)

A

American - Unified Inch Screw Thread

Formulas

DRILLING

1. RPM

= (3.82 • SFM) / DIA

Probable Mean Oversize

where: RPM = revolutions per minute (rev/min) SFM = speed (ft/min) DIA = diameter of drill (inch) 2. IPM = RPM • IPR where: IPM = inches per minute (in/min) RPM = revolutions per minute (rev/min) IPR = feed rate (in/rev)

Tap Drill Size

Decimal Equivalent

* Theo % Thread

Probable Hole Size

** Probable % Thread

Tap Size 1/2 - 20

29/64

0.4531

72% 72% 83% 87% 70% 65% 79% 72% 87% 75% 65% 72% 84% 77% 72% 72% 77% 75% 76% 65% 84% 67% 72% 72% 82% 77% 67% 87% 72% 67% 87% 72% 76%

0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003

0.4561 0.4754 0.4874 0.5030 0.5148 0.5186 0.5343 0.5499 0.5655 0.5739 0.5811 0.6124 0.6436 0.6526 0.6593 0.6749 0.6905 0.6920 0.7686 0.7843 0.7999 0.8155 0.8624 0.8936 0.8691 0.8780 0.8936 0.9093 0.9249 0.9405 1.0343 1.0499 1.1124

68% 69% 80% 82% 66% 61% 77% 69% 82% 71% 61% 69% 82% 75% 70% 69% 73% 71% 74% 63% 81% 64% 69% 68% 81% 75% 65% 84% 69% 64% 84% 69% 74%

12.0 mm 0.4724

9/16 - 12

31/64

0.4844 0.5000 0.5118 0.5156 0.5313 0.5469 0.5625 0.5709 0.5781 0.6094 0.6406 0.6563 0.6719 0.6875 0.6890 0.7656 0.7813 0.7969 0.8125 0.8594 0.8906 0.8661 0.8750 0.8906 0.9063 0.9219 0.9375 1.0313 1.0469 1.1094

1/2

9/16 - 18

13.0 mm

31/64 17/32 35/64

B

5/8 - 11 5/8 - 12

9/16

BORING

3. SFM

= RPM • 0.262 • DIA

5/8 - 18

14.5 mm

where: SFM = speed (ft/min) RPM = revolutions per minute (rev/min) DIA = diameter of drill (inch)

37/64

11/16 - 12 39/64

41/64

3/4 - 10

16.5 mm 0.6496

21/32 43/64 11/16 49/64 25/32 51/64 13/16

4. Thrust

= 153,700 • IPR • DIA • K m

3/4 - 12

where: Thrust

3/4 - 16

= axial thrust (lbs) = feed rate (in/rev)

17.5 mm

C

IPR DIA Km

7/8 - 9

= diameter of drill (inch)

= specific cutting energy (lbs/in 2 )

REAMING

7/8 - 14

5. Tool Power = .6991 • IPR • RPM • K m • DIA 2 where: Tool Power = tool power (HP) IPR = feed rate (in/rev) RPM = revolutions per minute (rev/min) Km = specific cutting energy (lbs/in 2 ) DIA = diameter of drill (inch)

15/16 - 12 55/64 15/16 - 20 57/64

22.0 mm

1 - 8

7/8

57/64 29/32 59/64 15/16 1-1/32 1-3/64 1-7/64

1 - 12

D

1 - 14

1-1/8 - 12

1-1/4 - 7 BURNISHING

Material Constants

Taper Pipe Thread (NPT)

Probable Mean Oversize

K m (lbs/in 2 )

Tap Drill Size

Decimal Equivalent

* Theo % Thread

Probable Hole Size

** Probable % Thread

Type of Material

Hardness

Tap Size 1/4 - 18 3/8 - 18 1/2 - 14 3/4 - 14

Plain Carbon and Alloy Steel

85 - 200 BHN 0.79 200 - 275 BHN 0.94 275 - 375 BHN 1.00 375 - 425 BHN 1.15

7/16 9/16

0.4375 0.5625 0.7031 0.9063

- - - -

0.003 0.003 0.003 0.003

0.4405 0.5655 0.7061 0.9093

- - - -

45/64 29/32

E

High-Temperature Alloys

- -

1.44 0.72

*Based on nominal tap drill diameter. **Based on 0.003" probable mean oversize.

THREADING

Titanium Alloy Stainless Steels

135 - 275 BHN 0.94 30 - 45 RC 1.08

To calculate the percent of full thread for a given hole diameter:

Cast Iron

100 - 200 BHN 200 - 300 BHN

0.50 1.08 0.43 0.72 0.22 0.16

(Basic major diameter of thread - Drill hole size) .0130

Copper Alloy

20 - 80 RB 80 - 100 RB

% Thread =

# of threads per inch •

Aluminum Alloy Magnesium Alloy

- -

X

Notes • The above tap drill information represents probable thread percentages for the standard tap drills stocked at Allied Machine. Special insert diameters may be required in order to meet a user specific percentage of thread requirement. • The 0.003" probable mean oversize hole condition is based on optimum cutting conditions. Probable percent of full thread may vary based on less ideal cutting conditions. • The table and equations on this page are found in the Machinery’s Handbook . Permission to simplify and print the equations is granted by the editor of the Machinery’s Handbook .

SPECIALS

A25: 56

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