ISO 8940:2002

Overview

ISO 8940:2002 specifies the dimensions and basic characteristics of self-locking, sealing, floating, two-lug anchor nuts with counterbore and metric MJ threads for the aerospace industry. Developed by the International Organization for Standardization (ISO), this standard targets the compilation of aerospace product standards and addresses nuts classified by their performance under specific conditions: 900 MPa at ambient temperature with temperature ratings of 120°C, 175°C, and 235°C.

Complying with ISO 8940:2002 helps ensure compatibility, performance, and reliability of critical fastener components in demanding aerospace applications.

Key Topics

• Product Scope: Defines anchor nuts that are self-locking, sealed, floating, and feature two lugs as well as a counterbore, using standardized MJ threads.
• Classification: Details classifications based on tensile strength (900 MPa at ambient temperature) and three maximum temperature ratings (120°C, 175°C, 235°C).
• Dimensions and Configuration: Specifies dimensions in millimetres and covers design features such as shell, seal, retainer, and threaded element. All tolerances are referenced to ISO 8788.
• Compatibility: Ensures that parts manufactured according to this standard align with procurement specifications and interface seamlessly with other aerospace fastener standards, specifically ISO 5858 and ISO 5855-2.
• Manufacturing Considerations: Allows manufacturers discretion in certain form details where not explicitly defined, enabling flexibility while maintaining interchangeability.

Applications

ISO 8940:2002 is essential in the design, manufacture, and specification of anchor nuts for aerospace fastener systems, particularly where high performance and operational reliability are critical. Practical applications include:

• Aircraft and Spacecraft Assembly: Providing secure, vibration-resistant joints in primary and secondary structures.
• Component Integration: Used in situations requiring floating nuts that accommodate minor misalignment, frequent disassembly, or tight sealing requirements.
• Maintenance and Repair: Allowing for consistent replacement or retrofit in line with international aerospace product standards.
• Product Standardization: Serving as a reference for drafting and evaluating technical requirements in aerospace procurement documentation.

Using anchor nuts that comply with ISO 8940:2002 ensures standardization, which simplifies logistics, improves safety, and supports international collaboration among aerospace manufacturers and suppliers.

Related Standards

Organizations following ISO 8940:2002 should also consider these relevant standards:

• ISO 5855-2:1999: Aerospace - MJ threads - Part 2: Limit dimensions for bolts and nuts
• ISO 8788:2000: Aerospace - Nuts, metric - Tolerances of form and position
• ISO 5858:1999: Aerospace - Nuts, self-locking, with maximum operating temperature less than or equal to 425°C - Procurement specification
• ISO 13715:2000: Technical drawings - Edges of undefined shape - Vocabulary and indications

Conclusion

Implementing ISO 8940:2002 for anchor nuts in aerospace projects supports the highest levels of product quality, consistency, and safety. By adhering to internationally recognized dimensions and classifications, manufacturers and suppliers facilitate better integration, streamlined procurement, and enhanced reliability in the demanding aerospace sector.