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Starting Feed
Table 5 contains data for estimating starting feed per tooth. Smaller values more suitable for
finish operations and greater feeds usually characterize rough milling. In case of high tool overhang
and unstable technological system (poor clamping, cutting thin wall workpieces and so on),
the feed should be reduced by 20-30%.

Starting Speed

Vc = Vo x Ks x Kt (1)

Where: Vc – starting cutting speed
Vo – basic cutting speed
Ks – stability factor
Kt – tool life factor

a) Basic cutting speed Vo

Table 9 determines the basic cutting speed depending on carbide grade, workpiece
material and type of machining. The basic cutting speed relates to a 20 minute tool-life period.
In order to define what is known as light duty, moderate duty and heavy duty machining
more rigorous, we introduce the following two-step procedure.

Tooth Loading
In shoulder milling, tooth loading is a function of the ratios:
• Cutting depth h to a length of cutting edge ap Milling Tools
• Width of cut b to the nominal diameter of a milling tool D
The tooth loading reflects a fraction of the cutting edge involved in cutting and a cycling path
of the tooth in the workpiece material from the tooth entering to the tooth exit.
While remaining in the material too long, the tooth experiences more intensive heat loads that
affect the tool life.
The diagram shown in Fig. 1 allows defining the tooth load, but for a quick rough
estimate, Table 6 may be enough.

Type of Machining
The tooth load in combination with the feed per tooth defines the type of machining (Table 7).
The feed interval from fz min to fz max relate to a field of the estimated starting feeds as above.
Do not take literally “minimum”, “maximum” and “moderate” feeds: the feeds
closed to the lower border of the field relate to fz min, the average values – to fz moderate,
and the feeds closed to the upper border – to fz max.

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Die and Mold