Page 147 - Threading_Handbook

Feed (F)

Feed per revolution (F) always is a constant value that equal to the threading pitch.

For example:

• In order to produce threading with a 2 mm pitch, the feed will be 2 mm/rev THREAD TURNING
(mm per revolution).
• In order to produce threading with 14 TPI, the feed will be 1.8 mm/rev (mm per revolution).
In this case, the definition of the value of the feed per revolution (F) is required to convert a
value of TPI to pitch in mm, i.e.
25.4 ≈ 1.8 mm
14 TPI

Usable Formulas

1 inch = 25.4 mm

25.4
= Pitch (mm)
T.P.I

Cutting Speed (Vc)

The starting cutting speed can be defined as the following formula:

Vc = Ks x Vo

When:
Vc — Starting cutting speed

Ks — Stability factor
Vo — Basic cutting speed

Stability Factor (Ks) is defined by the below estimate of threading operation stability:

For normal stability: Ks=1
For unstable operations such as: high overhang, poor clamping and etc.: Ks=0.7

• Basic cutting speed (Vo) is determined in the table below,
according to carbide grade and workpiece material.

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