Formulae
Table of formulae
| Parameter | Formula | Unit of measurement |
|---|---|---|
| Cutting speed (Vc) | N · π · d11000 | mmin |
| Rotational speed (N) | 1000 · Vcπ . d1 | rpm |
| Torque* (Mt) | Kc · p2 · z0,6 · d1104 | N·m |
| Spindle power (P) | Mt · 2 · π · N60 | W |
| Nominal diameter | d₁ | mm |
| Feed | p·N | mmmm |
| p | Thread pitch | mm |
| z | Number of flutes | — |
| Kc | Cutting force coefficient (function of the material and of tap wear) | Nmm² |
Material reference
| Material group | Kc [N/mm²] | |
|---|---|---|
Steel | ||
P.1 | Mild / magnetic steel | 1300 |
P.2 | Construction steel, case hardening steel | 1400 |
P.3 | Carbon steel | 1400 |
P.4 | Alloyed steel / tempered steel | 1600 |
P.5 | Alloyed steel / tempered steel | 1700 |
P.6 | Alloyed steel / high strength steel | 2000 |
P.7 | Ferritic stainless steel, martensitic stainless steel, precipitation hardening | 1400 |
Stainless steel | ||
M.1 | Austenitic stainless steel | 1600 |
M.2 | Ferritic+austenitic (Duplex) | 1800 |
Cast iron | ||
K.1 | Grey cast iron | 1100 |
K.2 | Nodular cast iron, malleable cast iron, tempered cast iron | 1500 |
K.3 | Austempered ductile iron (ADI) | 1600 |
Non-ferrous metals | ||
| Pure aluminium | 600 | |
| High strength magnesium alloys | 500 | |
| Aluminium wrought and die cast alloys with Si < 0,5% (long chipping) | 800 | |
| Aluminium wrought and die cast alloys with Si > 10% (medium chipping) | 900 | |
| Aluminium die cast alloys with Si > 10% (short chipping) | 1000 | |
| Pure copper | 700 | |
| Copper alloys (long chipping), soft brass | 850 | |
| Copper alloys (short chipping), hard brass | 900 | |
| High strength bronze | 2500 | |
| Pure magnesium, magnesium alloys | 400 | |
Super alloys and titanium | ||
S.1 | Pure titanium | 1200 |
S.2 | Titanium alloys | 1900 |
S.3 | Pure nickel | 1300 |
S.4 | Nickel alloys | 2400 |
Hardened materials | ||
H.1 | Alloyed steel, hardness HRC 44-55 | |
H.2 | Alloyed steel, hardness HRC 56-63 | |
(*) The torque value is valid for a new cutting tap. For worn-out taps, the value can increase up to 2-3 times. For forming taps, the value must be multiplied by 1,5-2 times.
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