Overview
ISO 8020:2002 defines standardized dimensions and tolerances, in millimetres, for pressing punches with a cylindrical head and either a straight or reduced shank. It covers round, oblong, square and rectangular point shapes and gives examples of suitable materials and hardness values. Shank diameters covered run from 3 mm to 32 mm. The primary application is punching holes in steel sheet, although the punches may also be used on other materials.
Key topics and requirements
- Dimensional specifications and tolerances: Basic dimensions (head, shank, point lengths and diameters) are provided in figures and tables. General tolerances conform to ISO 2768-1 (tolerance class m).
- Types and variants: Standardized types include straight-shank (Type A), reduced-shank round (B), square/rectangular/oblong reduced shank (BS, BR, BO), pilot and positive pilots (C, D), and ejector versions (E, F, FS, FR, FO).
- Surface finish: Surface roughness values and tolerancing notes are included for relevant features.
- Material and hardness guidance: Examples given - alloyed cold work steel (5–12% Cr) and high speed steel, with typical hardness ranges for point and head (e.g., point ≈ 60 ±2 HRC for cold work steel; point ≈ 62 ±2 HRC for HSS).
- Designation system: A standardized naming format is specified (e.g., Punch ISO 8020‑B‑5××2 71‑alloyed cold work steel), indicating standard reference, type, shank diameter, point dimensions, overall length and material.
- Manufacturer discretion: Certain dimensions (point length, specific point shape, ejector components, locking holes) are left to the manufacturer within the standard’s constraints.
Practical applications
- Tooling design and production for metal forming shops and die manufacturers.
- Specifying replacement punches for press lines to ensure interchangeability.
- Procurement and quality control: provides clear acceptance criteria for dimensions, tolerances and hardness.
- Workshop setup: helps press operators and maintenance teams select the correct punch type (pilot, ejector, reduced shank) for a given die set or material.
Who uses this standard
- Toolmakers and die designers
- Press-shop engineers and maintenance technicians
- Purchasing and inspection teams specifying or verifying punch tooling
- Manufacturers of punches and press tooling components
Related standards
- ISO 8695:1987 - Tools for pressing - Punches - Nomenclature and terminology
- ISO 2768-1:1989 - General tolerances for linear and angular dimensions
- Note: ISO 8020:2002 supersedes earlier editions (e.g., replaced ISO 8021:1986 in its scope updates)
Keywords: ISO 8020, punches, cylindrical head, reduced shank, punch dimensions, press tooling, shank diameter, punching holes, tooling standards, hardness, tolerances.
