Page 630 - Yamawa_European_Catalogue_YEU23

5. Tapping Torque

Intro

Calculation for Tapping Torque of Roll Taps
SP It is hard to calculate the tapping torque for roll taps because they contain more complicated factor than the cutting taps.

According to our experience, the tapping torque of roll taps is twice or three times larger than that of the cutting taps in general.
Major factors increasing or decreasing the tapping torque of roll taps are :
SL (1) Mechanical characteristic of workpiece (Tensile strength, hardness, spring back feature, work hardening index). As the tensile strength
gets larger, the threading torque becomes larger.
(2) Size and length of bored hole: bored hole size is usually defined to obtain 75% thread height of basic thread profile (thread engagement).
Roll taps may be shuttered due to the excessive tapping torque when the bored hole size is made smaller to obtain higher thread height.
Tapping torque gets larger as the efficient length of internal screw becomes longer because there is an increase in friction coefficient
PO caused by spring back of workpiece material.
(3) Tapping process (tapping speed, lubricant, and rigidity of main spindle).
(4) Surface treatment of taps (oxidizing, nitriding, TiN, and TiCN coatings).

ST
Tapping Torque Equation for Forming Taps
The following equation provides an estimation of the tapping torque for standard forming taps, based on the tensile strength of the
workpiece material.
ROLL Condition : Effective length of internal screw is 1.5D. Thread height is 75%.

Deforming resistance
Tapping Torque Equation for Forming Taps Workpiece Materials N/mm 2
General Structure Steels, Low Carbon Steels 750-850
CARBIDE
Medium Carbon Steels, Alloy Steels 1150-1350
T = Kf x Dc x P2/1000
Stainless Steels 1100-1300
Wrought Aluminum 250-350
T : Tapping Torque (Nm)
Aluminum Die Castings 380-530
LONG Dc : Nominal Diameter of Tap (mm)
P : Pitch (mm) Coppers, Wrought Copper Alloys 750-1050
Kf : Deforming resistance (N/mm ) 2
HAND
TAPS

EG (STI)

SPECIAL
THREADS,
GAUGES

THREAD
MILLS

DIES

CENTER
DRILLS

Technical
info

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