Overview
ISO 7380-3:2026 defines the requirements for hexalobular socket button head screws with reduced loadability, made of steel or stainless steel. This international standard focuses on screws with metric coarse pitch threads (M3 to M12), product grade A, and incorporates distinctive characteristics resulting from their head geometry and hexalobular internal drive. Reduced loadability signifies a maximum tensile load that is less than full-headed variants, a consequence of both the button head design and the depth of socket penetration. The standard details marking, material options, dimensional specifications, and relevant references to ensure quality and interoperability for manufacturers and end-users.
Key Topics
- Hexalobular Socket Design: Specifies internal driving features as per ISO 10664, supporting enhanced torque transmission and reduced cam-out during installation.
- Reduced Loadability: Establishes that the maximum loadability in the screw head is 80% of that in the thread, suitable for applications that do not require maximum tensile strength and indicated by a zero-prefixed property class (e.g., 010.9, A2-070).
- Material Specifications: Covers screws produced in steel and corrosion-resistant stainless steel. Property classes and grades may be selected from ISO 898-1 (for steel) and ISO 3506-1 (for stainless steel).
- Dimensional Consistency: Refers to ISO 888 and ISO 4753 for length and end features. Ensures metric thread dimensions and tolerances are met (M3-M12).
- Marking and Labelling: Prescribes clear identification on products and packaging, including standard reference, size, property class or grade, surface finish, and lot traceability, complying with ISO 898-1 or ISO 3506-1.
- Surface Treatment: Allows for coatings such as electroplated finishes (ISO 4042) or zinc flake coatings (ISO 10683), and supports passivation for stainless steel components.
- Acceptance and Inspection: References ISO 3269 for inspection procedures and ISO 6157-1 for limits on surface discontinuities, ensuring fitness for purpose and reliability.
Applications
Hexalobular socket button head screws with reduced loadability are widely used in industries where the appearance and safe torqueing of components are critical, but maximum tensile performance is not the primary requirement. Key application areas include:
- Consumer Products: Used in electronics, appliances, and automotive interiors where a low-profile and tamper-resistant head is beneficial.
- Industrial Assembly: Ideal for mechanical enclosures, machinery guards, and light structural frameworks where frequent access or adjustments may be anticipated.
- Architectural Hardware: Suited for fittings and fixtures where aesthetics and flush-mounting are desirable, but with moderate structural demands.
- Stainless Steel Variants: Particularly applicable in environments requiring corrosion resistance, such as medical devices, food processing equipment, and outdoor installations.
When property class and corrosion resistance are critical, users should reference compatible grades from ISO 898-1 or ISO 3506-1 and surface finishes as specified in related standards.
Related Standards
ISO 7380-3:2026 references and aligns with several other ISO standards to ensure full compatibility and comprehensive guidance:
- ISO 7380-1 - Button head screws with reduced loadability: Hexagon socket (part 1)
- ISO 7380-2 - Button head screws with reduced loadability: Hexagon socket with collar (part 2)
- ISO 7380-4 - Button head screws with reduced loadability: Hexalobular with collar (part 4)
- ISO 898-1 - Mechanical properties of steel fasteners
- ISO 3506-1 - Mechanical properties of stainless steel fasteners
- ISO 888, ISO 4753 - Fastener dimensions and end types
- ISO 10664 - Hexalobular drive details
- ISO 4042, ISO 10683 - Surface coatings and treatments
- ISO 3269, ISO 6157-1 - Acceptance inspection and surface integrity
- ISO 8991, ISO 8992 - Fastener designation and general requirements
By adhering to ISO 7380-3:2026, designers and manufacturers can ensure interoperability, quality, and safety for button head screws in a wide range of modern applications.