Overview
ISO 7332:1998 specifies the dimensions for a family of aerospace anchor nuts: self‑locking, floating, two‑lug, reduced‑series nuts with a counterbore and MJ threads. It covers nuts classified by strength/temperature capability: 1 100 MPa (at ambient temperature) with maximum operating temperatures of 235 °C, 315 °C and 425 °C. The standard is intended for compilation into aerospace product standards and provides the geometric basis for procurement, manufacturing and design documentation.
Key topics and requirements
- Configuration and dimensions: Figures and Table 1 in the standard define the geometry (diameters, widths, counterbore and lug features) and dimensional limits. Dimensions and tolerances are expressed in millimetres.
- Thread specification: MJ thread limits are referenced to ISO 5855‑2, so thread form and limit dimensions conform to that MJ thread standard.
- Self‑locking and floating features: The document applies to self‑locking, floating, two‑lug anchor nuts (reduced series) including details for the counterbore and locking zone.
- Material/temperature classifications: Nuts are classified by the minimum ambient tensile stress capability (1 100 MPa) and by maximum operating temperature (235 °C, 315 °C, 425 °C), where maximum temperature is tied to surface treatment and recovery of properties after cooling.
- Surface condition and measurement: Dimensions apply after any surface coating(s) but before application of lubricant. Form and position tolerances follow ISO 8788.
- Optional metallic cap: If fitted, the metallic cap must remain attached to the nut at its maximum operating temperature (test conditions referenced in ISO 5858).
- Intended use: The dimensions were determined to allow production of parts that satisfy the procurement specification ISO 5858.
Applications
ISO 7332:1998 is directly useful for:
- Aerospace fastener designers creating anchor nut geometry for structural joints
- Manufacturers and tooling engineers producing reduced‑series MJ threaded anchor nuts
- Procurement teams and specification writers compiling aerospace product standards and purchase documents
- Quality and inspection personnel checking dimensional conformity to aerospace requirements
- Certification and maintenance documentation where standardized fastener geometry is required
Who uses this standard
- Aircraft and space vehicle OEMs and suppliers
- Fastener manufacturers and specialty machinists
- Aerospace engineers (design, structural, systems)
- Procurement, QA, and standards committees within the aerospace supply chain
Related standards
- ISO 5855‑2:1988 - Aerospace - MJ threads - Limit dimensions for bolts and nuts
- ISO 5858:1991 - Aerospace - Self‑locking nuts (procurement specification)
- ISO 8788:1987 - Aerospace - Fasteners - Tolerances of form and position for nuts
Keywords: ISO 7332:1998, aerospace nuts, anchor nut, self‑locking nut, MJ threads, two‑lug floating nut, counterbore, dimensions, aerospace fasteners, ISO standards.