Overview
EN 22568:1989 (identical to ISO 2568:1988) specifies the general dimensions and interchangeability requirements for hand- and machine-operated circular screwing dies and hand-operated die stocks. The standard establishes dimensional rules for threading dies used to produce ISO metric threads (coarse and fine), ISO inch threads (UNC and UNF), and - in an informative annex - non‑ISO inch threads (BSW, BSF, BA). It also covers marking conventions and tolerance classes for precision and non‑precision dies.
Key topics and technical requirements
- Scope of threads covered
- ISO metric coarse: M1 to M68
- ISO metric fine: M1 to M56
- ISO inch (UNC): ranges from No. 1‑64 up to larger inch sizes shown in the standard
- ISO inch (UNF): ranges from No. 0‑80 up to sizes listed in the standard
- Annex B: guidance dimensions for BSW, BSF and BA series (informative)
- Dimensional parameters defined
- Outside diameter (D)
- Thickness and cutting portion length (C)
- General dimensions of attachments and chamfers
- Die‑stock interchangeability dimensions (for hand die stocks)
- Classes and tolerances
- Two classes: precision and non‑precision screwing dies
- Precision tolerances specified (e.g., D: f10; E: js12); non‑precision tolerances are left to the manufacturer’s discretion
- Tables and annexes
- Annex A: detailed dimensional tables for metric and inch threads
- Annex B: non‑ISO inch thread dimensions (informative)
- Marking
- Required marking format with examples (e.g., M12 x 1.25, 1/4‑20‑UNC, No. 12‑28‑UNF, BA No. 4)
- Option to append the ISO symbol when fully compliant
Practical applications and users
- Tool manufacturers producing circular screwing dies and die stocks - to ensure dimensional conformity and interchangeability.
- Toolroom and machine shops selecting threaded tooling for production or repair.
- Procurement and quality engineers specifying and inspecting dies for assembly lines or maintenance.
- Design engineers needing standard die dimensions to match fixtures or tool-holders.
- Technical training and documentation for standards-based tool selection and marking.
Using EN 22568 / ISO 2568 helps organizations achieve consistent thread quality, interchangeability of hand die stocks, and clear marking for traceability.
Related standards
- ISO 4230 (referenced for taper-pipe “R” series threads) - see ISO 4230 for taper thread die details.
- National adoptions: this ISO text was adopted as EN 22568 and later as national variants (e.g., SIST EN 22568).
Keywords: circular screwing dies, hand-operated die stocks, ISO 2568, EN 22568, threading dies dimensions, metric threads, UNC UNF, BSW BSF BA, die stock interchangeability, precision screwing dies, die marking.