SK40 is an international standard for tool taper applied in milling and drilling operations on CNC and traditional metalworking machines. It is widely used in industry due to its reliability, versatility and stability under high loads.
What is SK40?
SK40 (ISO 7388-1 or DIN 69871) is a type of tapered shank with an angle of 7:24, designed for installing milling and drilling tools in the machine spindle. Its geometry provides a strong, accurate and repeatable connection.
Advantages of the SK40 standard
- Versatility: Suitable for most milling machines, including CNC machines and machining centers.
- Rigid fit: The 7:24 conical shape provides high rigidity and minimal runout at high speeds.
- Compatibility: The standard is compatible with various types of holders and chucks - ER, APU, OZ, Weldon, etc.
- Wide range of tools: Drilling, milling, boring chucks and arbors are available in various sizes.
- Suitable for automatic tool change: Used in ATC (automatic tool change) systems due to the presence of a gripper groove and standard shank length.
SK40 Application
SK40 shank tool is used in:
- Milling and drilling of various metals
- Finishing and roughing of parts
- Mechanical engineering, aircraft and automotive industries
- Production of molds and dies
Conclusion
The SK40 tool taper remains one of the most popular standards in metalworking. Due to its reliability, accuracy and wide compatibility, it is used both in serial production and in individual processing. The correct choice of tooling according to the SK40 standard ensures stable and highly efficient operation on milling machines.
| Model | L1 | L2 | L3 | L4 | L5 | L6 | d1 | d2 | d3 | d4 | d5 | b | T |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| SK30 | 47.8 | 5.5 | 24 | 16.4 | 19 | 15 | 31.75 | 13 | 59.3 | 50 | 44.3 | 16.1 | M12 |
| SK40 | 68.4 | 8.2 | 32 | 22.8 | 25 | 18.5 | 44.45 | 17 | 72.3 | 63.66 | 56.25 | 16.1 | M16 |
| SK50 | 101.8 | 11.5 | 47 | 35.5 | 37.7 | 30 | 69.85 | 25 | 107.25 | 97.5 | 91.25 | 25.7 | M24 |