Overview
ISO 2936:2014 - Assembly tools for screws and nuts - Hexagon socket screw keys - defines the dimensional, testing, designation and marking requirements for hexagon socket screw keys (commonly called Allen keys or socket screw keys). The standard also specifies minimum Rockwell hardness values and proof-torque test procedures to ensure durability and safe tightening of hexagon socket screws (property class ≤ 12.9 per ISO 898‑1) and socket set screws (ISO 898‑5).
Key topics and technical requirements
- Dimensions and tolerances: Nominal widths across flats, corresponding widths across corners, and standard lengths (short, long, extra‑long) are given (see Table 1 in the standard). Corner radii, end squareness and allowable angular tolerances are specified.
- Material hardness: Keys must be through-hardened over their whole length. Test adapter hardness requirements: 60 HRC minimum for keys with s ≤ 17 mm, and 55 HRC minimum for s > 17 mm.
- Method of test / proof torque: The short arm is inserted into a hardened hexagon socket adapter; a lateral load is applied at a distance m = l/3 (±2 mm) on the long arm until the proof torque is reached. Test values and proof-torque requirements per key size are provided in Table 3. For keys ≤ 14 mm, the standard requires a torsional deformation to fracture of at least 60° under load.
- Designation and marking: Designation format - e.g., “Socket screw key ISO 2936‑10”, with suffix M for long and L for extra‑long. Keys ≥ 3 mm must be permanently marked (manufacturer/trademark and width across flats) either on the tool or on packaging.
Applications and users
ISO 2936 is relevant for:
- Tool manufacturers and designers producing hexagon socket screw keys
- Fastener suppliers and quality assurance teams verifying tool performance
- Maintenance, assembly and production engineers in automotive, aerospace, industrial machinery and electronics sectors
- Procurement and compliance officers specifying tools to meet international standards
Practical benefits include predictable fit and torque transmission, improved tool life, safer tightening of high‑strength fasteners, and clear product identification for inventory and traceability.
Related standards
- ISO 898‑1 (mechanical properties of bolts/screws - property classes)
- ISO 898‑5 (mechanical properties of set screws)
- ISO 1703 (designation and nomenclature of assembly tools)
Keywords: ISO 2936, hexagon socket screw keys, socket screw key, assembly tools, Rockwell hardness, proof torque, dimensions, marking, ISO standard.
