A30-TAS_EU-EN

DRILLING | T-A® Replaceable Insert Drilling System

Tap Drill Information and Formulas | Metric (mm)

A

Metric Profile Screw Thread

Formulas 1. RPM = (318.47 • m/min) / DIA where: RPM

Probable Mean Oversize

Tap Drill Size

Decimal Equivalent

* Theo % Thread

Probable Hole Size

** Probable % Thread

DRILLING

= revolutions per minute (rev/min)

Tap Size

m/min

= speed (m/min)

12 x 1.75 10.2 mm 0.4016"

79% 74% 79% 74% 81% 77% 77% 77% 77% 68% 77% 77% 68% 78% 77% 77% 69% 79% 77% 77% 70% 86% 76% 77% 68% 77%

0.075 mm 10.28 mm 0.075 mm 10.40 mm 0.075 mm 10.79 mm 0.075 mm 10.88 mm 0.075 mm 11.98 mm 0.075 mm 12.08 mm 0.075 mm 12.58 mm 0.075 mm 14.08 mm 0.075 mm 14.58 mm 0.075 mm 14.76 mm 0.075 mm 15.58 mm 0.075 mm 16.58 mm 0.075 mm 16.75 mm 0.075 mm 17.54 mm 0.075 mm 17.58 mm 0.075 mm 18.58 mm 0.075 mm 18.66 mm 0.075 mm 19.52 mm 0.075 mm 19.58 mm 0.075 mm 20.58 mm 0.075 mm 20.71 mm 0.075 mm 20.71 mm 0.075 mm 21.08 mm 0.075 mm 22.08 mm 0.075 mm 22.30 mm 0.075 mm 24.08 mm

76% 71% 74% 69% 78% 74% 73% 74% 73% 64% 75% 73% 64% 76% 74% 73% 65% 76% 75% 73% 66% 84% 75% 74% 65% 75%

DIA

= diameter of drill (mm)

12 x 1.75 13/32" 12 x 1.25 27/64"

0.4063" 0.4219"

2. mm/min = RPM • mm/rev where: mm/min

12 x 1.25 10.8 mm 0.4252"

14 x 20

15/32"

0.4688"

= mm per minute (mm/min)

14 x 20 12.0 mm 0.4724" 14 x 1.5 12.5 mm 0.4921" 16 x 2.0 14.0 mm 0.5512" 16 x 1.5 14.5 mm 0.5709"

RPM

= revolutions per minute (rev/min)

mm/rev

= feed rate (mm/rev)

B

3. m/min

= RPM • 0.003 • DIA

16 x 1.5

37/64"

0.5781"

where: m/min

18 x 2.5 15.5 mm 0.6102" 18 x 1.5 16.5 mm 0.6496"

= speed (m/min)

BORING

RPM

= revolutions per minute (rev/min)

18 x 1.5 20 x 2.5

21/32" 11/16"

0.6563" 0.6875"

DIA

= diameter of drill (mm)

20 x 2.5 17.5 mm 0.6890" 20 x 1.5 18.5 mm 0.7283"

4. Thrust

= 154 • (mm/rev) • DIA • K m

where: Thrust mm/rev

20 x 1.5 22 x 2.5

47/64" 49/64"

0.7344" 0.7656"

= axial thrust (N)

= feed rate (mm/rev) = diameter of drill (mm)

22 x 2.5 19.5 mm 0.7677" 22 x 1.5 20.5 mm 0.8071"

DIA

K m

= specific cutting energy (kPa)

22 x 1.5

13/16" 13/16"

0.8125" 0.8125"

C

24 x 3 24 x 3 24 x 2 24 x 2 27 x 3

5. Tool Power

= ((mm/rev) • RPM • K m • DIA

2 ) / 210604.8

21.0 mm 0.8268" 22.0 mm 0.8661"

where: Tool Power = tool power (HP) mm/rev

REAMING

7/8"

0.8750"

= feed rate (mm/rev)

24.0 mm 0.9449"

RPM

= revolutions per minute (rev/min) = specific cutting energy (kPa)

K m

DIA

= diameter of drill (mm)

Taper Pipe Thread (NPT)

Material Constants

D

Probable Mean Oversize

Tap Drill Size

Decimal Equivalent

Theo % Thread*

Probable Hole Size

Probable % Thread**

K m (kPa)

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

Type of Material

Hardness

BURNISHING

7/16 9/16

0.4375 0.5625 0.7031 0.9063

- - - -

0.075 mm 11.19 mm - 0.075 mm 14.76 mm - 0.075 mm 18.33 mm - 0.075 mm 23.89 mm -

Plain Carbon and Alloy

85 - 200 BHN 5.45 200 - 275 BHN 6.48 275 - 375 BHN 6.89 375 - 425 BHN 7.93 135 - 275 BHN 6.48 30 - 45 RC 7.45 100 - 200 BHN 3.45 200 - 300 BHN 7.45 - 9.93

Steel

45/64 29/32

High-Temperature Alloys

* Based on nominal tap drill diameter ** Based on 0.075 mm probable mean oversize

Stainless Steels

Cast Iron

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

Copper Alloy

20 - 80 RB 80 - 100 RB

2.96 4.96 4.96 1.52 1.10

E

76.93 Pitch (mm)

Titanium Alloy Aluminium Alloy Magnesium Alloy

- - -

Basic Major Diameter of Thread (mm) - Drill Hole Size (mm)

% Thread =

THREADING

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 requirements. • The 0.0075 mm 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

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