ISO 26623-1:2020

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:

• POLYGON SHANK ISO 26623-1 - PSC 32

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.