Overview
ISO 14579:2011 defines the characteristics of hexalobular socket head cap screws (hexalobular internal drive) with metric thread sizes M2 to M20, for product grade A. The second edition (2011) updates dimensional, material and inspection references and provides the standardized format for designation, dimensional tables and mass information for carbon steel screws. ISO 14579 is aimed at ensuring interchangeability, quality and consistent specification of hexalobular head screws across industries.
Key topics and requirements
- Scope and product grade: Covers hexalobular socket head cap screws of product grade A with threads M2–M20.
- Dimensions and tolerances: Detailed head, socket and thread dimensions are provided (figures and Table 1) - including nominal lengths, head heights, socket sizes and underhead fillets.
- Thread standards: Threads referenced to ISO general-purpose metric thread standards (ISO 261, ISO 965-2/3) and tolerance classes (notably 5g/6g depending on property class).
- Materials and mechanical properties: Acceptable materials include carbon steel, stainless steel and non-ferrous metals; mechanical property classes referenced (e.g., ISO 898-1, ISO 3506-1). Special notes for high-strength classes (e.g., 12.9) and hardness testing are included.
- Hexalobular socket specification: Socket geometry and gauges referenced to ISO 10664 (hexalobular internal driving feature).
- Surface finish and coatings: Electroplating and coatings requirements referenced to ISO 4042 and non-electrolytic zinc flake coatings to ISO 10683.
- Surface integrity, inspection and acceptability: Surface discontinuity limits and acceptance inspection procedures referenced to ISO 6157-1/3 and ISO 3269.
- Designation and mass data: Standardised designation example and informative annex with approximate masses per 1 000 pieces for carbon steel screws.
Applications and users
ISO 14579 is essential for:
- Fastener manufacturers and tooling suppliers (ensuring compliant production and gauges)
- Design and mechanical engineers specifying fasteners in assemblies
- Procurement and quality assurance teams validating suppliers and incoming inspection
- OEMs in automotive, machinery, electronics and general manufacturing where compact hexalobular drives are used
- Maintenance and repair organisations requiring standardized replacement parts
Using ISO 14579 helps ensure compatibility of hexalobular socket head cap screws, reliable mechanical performance and consistent quality control.
Related standards
Relevant referenced documents include:
Keywords: ISO 14579:2011, hexalobular socket head cap screws, hexalobular internal drive, M2–M20, fastener standards, dimensions, tolerances, mechanical properties, ISO 10664.