Assembly tools for screws and nuts - Adjustable wrenches
1Key Takeaways
This document specifies the dimensions of adjustable wrenches and the admissible clearance of the adjustable jaw. It also specifies test conditions to test the suitability of tool performance. NOTE The wrenches covered by this document are the ones identified in ISO 1703:2005 under reference number 1101040.
2Expert Interpretation
A comprehensive analysis of the ISO 6787:2018 international standard for adjustable wrenches, covering dimensional specifications, jaw gap requirements, hardness standards, and torque test methods. Learn key updates and tool performance test conditions, and gain a technical guide to professional-grade assembly tools.
Analysis of the core content of the standard
The third edition of ISO 6787:2018 has made technical revisions to the manufacturing specifications for adjustable wrenches. The main updates include:
- Updated the reference number of ISO 1703:2005
- Corrected the test mandrel width across flats and torque values in Table 2
- Added an annotation on ISO 1711-1:2016
Key dimensions and technical parameters
| Length l (mm) | Maximum jaw opening smax (mm) | Jaw depth h (mm) | Permissible gap c (mm) |
|---|---|---|---|
| 100 | ≥13 | 10 | 0.25 |
| 300 | ≥34 | 26 | 0.30 |
| 600 | ≥60 | 48 | 0.50 |
Note: The movable jaw should not be stuck in the full stroke range
Material hardness requirements
The standard stipulates that the overall hardness of the wrench head shall not be less than 40 HRC, the test mandrel hardness must be ≥55 HRC. In practical applications:
- Typical hardness range of chrome vanadium steel: 42-48 HRC
- Heat treatment process must ensure hardness uniformity
Torque test specification
Bidirectional torque test is carried out in accordance with ISO 1711-1. Key test parameters:
| Wrench length (mm) | Test mandrel width across flats (mm) | Minimum test torque (N·m) |
|---|---|---|
| 200 | 24 | 230 |
| 450 | 50 | 1,373 |
Technical points: There should be no permanent deformation or defects that affect use after testing
Implementation recommendations
- Check the integrity of the markings, including length specifications and manufacturer identification, when purchasing
- Regularly check the jaw gap with a standard measuring tool to ensure that it is ≤ the limit in Table 1
- The torque test frequency is recommended to be every 5000 operations or 12 months (whichever comes first)
- Distinguish between different application scenarios of Type A (15°) and Type B (22.5°) designs