Overview
ISO 6787:2018 specifies the dimensional requirements and performance test conditions for adjustable wrenches used for screws and nuts. The standard defines maximum jaw openings, head and jaw tip dimensions, and the permissible clearance of the adjustable jaw. It also sets key technical requirements for hardness and torsion testing to verify tool suitability and durability.
This edition updates test mandrel and torque values and aligns torque testing with ISO 1711-1 procedures. The standard supports consistent manufacturing, safer use, and interchangeability of adjustable wrenches across markets.
Key Topics
- Dimensions: Nominal wrench lengths, maximum jaw opening, jaw depth and thickness are specified in tabulated form. Designers and manufacturers should use Table 1 dimensions as the baseline for product geometry.
- Jaw clearance: The clearance (c) between adjustable and fixed jaws is measured under a light force. Clearance must not exceed the maximum values defined for each size; the adjustable jaw must travel freely without binding.
- Hardness: Wrenches shall have a minimum hardness of 40 HRC, tested over the whole head to ensure adequate wear and strength.
- Torque (torsion) test: Tests are performed on a hexagon test mandrel hardened to at least 55 HRC, following the procedure in ISO 1711-1. Test torque values vary by wrench length and mandrel width (Table 2) and are applied in both directions. After testing, tools shall show no permanent deformation or defects that affect use.
- Designation and marking: Products are designated with the standard reference, form (A or B), angle (α) and length (l). Example: Wrench ISO 6787 – A 15 × 250. Marking must include nominal length and manufacturer name or trademark.
Applications
ISO 6787:2018 is relevant for:
- Tool manufacturers specifying and verifying adjustable wrench geometry and performance.
- Quality and test laboratories performing hardness and torsion tests on hand tools.
- Procurement teams and engineers seeking consistency, safety, and interchangeability in hand tools used in maintenance, assembly and mechanical work.
Adopting this standard helps reduce product variability, improves user safety by limiting jaw play and ensuring minimum hardness, and provides objective test methods for warranty and acceptance testing.
Related Standards
- ISO 1711-1 - referenced for detailed torque test procedures and general wrench/socket test methods.
- ISO 1703 - relates to designation and classification of assembly tools for screws and nuts.
- ISO 6508-1 - Rockwell hardness test method referenced for hardness verification.
For implementation, consult the full ISO 6787:2018 document for complete tables, figures and test value specifics.
