Overview - ISO 26623-1:2020 (Polygonal taper interface, shank dimensions)
ISO 26623-1:2020 specifies the dimensions and designation of polygonal taper shanks with a flange contact surface for automatic and manual tool exchange on machine tools (turning, drilling, milling, turn/mill centres, grinding). The standard defines a range of nominal shank sizes (32, 40, 50, 63, 80, 100 mm), flange features for automatic exchange, clamping options (circular groove with clamping segments or internal screw thread with centre-bolts) and the method of torque transmission by form lock (polygon).
Example designation:
Key topics and technical requirements
- Dimensional data: Complete geometry for polygon shanks (external profile, gauges, flanges, chip-hole options) with detailed figures and Table 1 size data.
- Tolerances: Linear and geometric tolerances are to follow ISO 2768 (m / K classes); thread tolerances per ISO 965-2. Specific small-dimension tolerances are given (e.g., ±0.05 mm for 0–0.2 mm).
- Clamping and flange contact: Shanks include a grooved flange enabling automatic tool exchange. Clamping must ensure flange-to-receiver contact for interface stiffness.
- Clamping force guidance (Annex A): Recommended clamping forces by nominal size (kN): 32→15, 40→20, 50→25, 63→30, 80→40, 100→60. These values ensure at least 80% of the clamping force acts on the flange under tolerance variation.
- Medium-transfer unit: Interfaces must be compatible with medium-transfer units described in ISO 22402-2.
- Dynamical balancing & material: Annex A provides recommendations for dynamic balancing by design, surface hardness (e.g., HRC recommendations), heat treatment and balancing features for adapters and tools.
- Stationary tools: Annex B provides alternative dimensions where tools are stationary and require extra room for clamping or coolant.
Applications and who uses it
- Application: Design, manufacture and inspection of polygonal taper tool shanks and adapters used in automated tool changing systems on machine tools.
- Primary users:
- Tooling and machine-tool manufacturers (tool holders, adapters, cutters)
- Design and production engineers (automation and tool-change systems)
- Quality, inspection and R&D teams (tolerance control, balancing)
- Purchasers and standards/technical spec writers for machining centers
- Benefits: Ensures interchangeability, reliable torque transmission, consistent clamping behavior and supports automated tool-change workflows.
Related standards
- ISO 22402-2 - Medium-transfer units for polygonal taper interfaces (compatibility)
- ISO 965-2 - Metric thread tolerances (threads referenced)
- ISO 2768-1 / ISO 2768-2 - General linear and geometrical tolerances
Keywords: ISO 26623-1, polygonal taper interface, polygon shank, automatic tool exchange, clamping force, medium-transfer unit, tool holder, machine tools, dynamical balancing.
Open preview (PDF)Polygonal taper interface with flange contact surface — Part 1: Dimensions and designation of shanks
