ISO 2940-1:1974

Overview

ISO 2940-1:1974 specifies the fitting dimensions and centring-arbor details for milling cutters mounted on centring arbors with a 7/24 taper. The standard covers both single‑purpose and dual‑purpose mountings and applies to a wide range of cutter types - inserted‑tooth cutters (high‑speed steel or brazed carbide), and cutters with indexable carbide tips. Its purpose is to ensure interchangeability and reliable centring of milling cutters on defined spindle noses (including spindle nose No. 50 and No. 60 having a 7/24 taper).

Key topics and requirements

• Scope: Applies to arbor‑located milling cutters with inserted teeth or indexable carbide tips; supports single‑purpose and dual‑purpose mounting configurations.
• 7/24 taper interface: Defines the mating relationship between centring arbors and spindle noses in accordance with ISO/R 297 (7/24 tapers for tool shanks).
• Centring arbor dimensions: Specifies dimensions and arrangements to facilitate accurate centring of the cutter on the spindle nose (spigot shape left to manufacturer’s choice where not critical).
• Fitting and locating features:
  • Use of locating holes (typically four) for mechanical location;
  • Fits and tolerances such as H7 / H12 for relevant diameters, and a positional tolerance parameter for hole axes (see ISO/R 1101 for geometric tolerances).
• Tables and diagrams: The standard includes dimension tables and sectional diagrams that define nominal sizes, maximum/minimum limits and positional tolerance zones for different cutter diameters.
• Interchangeability rules: General fitting dimensions follow ISO/R 297 and its addendum to ensure compatibility across equipment and suppliers.

Applications and users

Who uses ISO 2940-1:

• Tool and cutting‑tool manufacturers specifying arbor and cutter bores
• Machine tool designers and spindle manufacturers ensuring interface compatibility
• Production and tooling engineers specifying replacement cutters and arbors
• Quality, inspection and maintenance teams verifying dimensional conformity Practical uses:
• Designing and manufacturing centring arbors and mating cutter bores
• Specifying replacement or retrofit milling cutters for spindles with 7/24 taper
• Establishing inspection criteria and acceptance limits for cutter‑to‑arbor assemblies
• Ensuring interchangeability between suppliers and machine tool fleets

Related standards

• ISO/R 297 - 7/24 tapers for tool shanks (general taper dimensions)
• ISO/R 1101 - Tolerances of form and position (geometric tolerances)
• ISO 2940-2 / ISO 2940/11 (related parts) - details for specific cutter types (inserted‑tooth cutters)

Keywords: ISO 2940-1, milling cutters, centring arbors, 7/24 taper, fitting dimensions, spindle nose No.50, spindle nose No.60, interchangeability, tooling standards.