Page 642 - Yamawa_European_Catalogue_YEU21

5. Tapping Torque

Intro

Tapping Torque of Cutting Taps
SP The torque starts increasing as the threads of thechamfer enter the workpiece material. It reaches the highest level when all the threads of the
chamfer cut into workpiece material, and is in plateau until the chamfer cuts through the workpiece. After that, the torque decreases until the
end of tapping.

SL Tapping Torque Equation for Cutting Taps Table 1 Specifi c cutting resistance of each material

Materials to be cut Specifi c cutting resistance kc N/mm 2
tanθ
Tc = . x kc × K(D-Do)² × (D+2Do) 2
24000 Material symbols Hardeness N/mm

5t44-2 133HB 3700
PO
Tc : Tapping Torque (Nm) Ck 15 141HB 3600
kc : Specifi c cutting resistance (N/mm ) 2 Ck 35 162HB 3700
K : Correction coeffi cient depending on tap geometry and chips Ck 45 188HB 3900
D : Nominal Diameter of Tap (mm)
Ck 60 188HB 4000
Do : Bored hole diameter (mm)
ST 42 CrMo 4 193HB 3600
θ : Thread half angle (°)
30HRC 4900
kc and K : Refer to Table 1 and Table 2 40HRC 5500
X 6 CrNi 18 10 209HB 4200
ROLL C 105 W2 175HB 5300
CnZn40 - 2300
G-AISi8Cu3 - 1300
GG-25 193HB 2900
CARBIDE

Table 2 Correction coeffi cient depending on each tap geometry
Coeffi cient K
LONG Materials to be cut Steel Cast iron + Alluminium alloys Brass
Kinds of tap coarse fi ne coarse fi ne coarse fi ne
Straight fl uted tap 5P 1.35 1.15 1.25 1.08 1.60 1.12
Straight fl uted tap 1.5P 1.43 1.50 1.30 1.25 1.68 -
HAND Spiral fl uted tap 1.15 1.25 1.05 1.10 0.85 -
TAPS
Spiral pointed tap 0.95 1.00 0.80 1.00 0.75 1.00

EG (STI)

SPECIAL
THREADS,
GAUGES

THREAD
MILLS

DIES

CENTER
DRILLS

Technical
info

640