Overview
EN 1663:1997 (CEN) covers prevailing-torque type hexagon nuts with flange that include a non‑metallic annular insert. The standard applies to coarse thread sizes M5 to M20 inclusive and references ISO 7043:1997 (modified). It defines product grades and property classes 8 and 10, establishing the characteristics required for reliable fastening performance where vibration resistance is needed.
Key topics and requirements
- Product scope: Prevailing-torque hexagon nuts with integral flange and a non‑metallic annular insert for coarse threads (designated “f”) from M5 to M20.
- Product grades:
- Grade A for threads up to and including M16
- Grade B for threads above M16
- Property classes: Applies to nuts manufactured to property classes 8 and 10, indicating mechanical performance categories.
- Performance focus: Specifies the characteristics and performance expected of prevailing-torque nuts - notably the presence and function of the non‑metallic insert to provide frictional resistance (prevailing torque) and reduce self-loosening.
- Standards relationship: Identical or derived from ISO 7043:1997 (modified) as indicated in the document extract; published under the European Standard system by CEN.
(Note: EN 1663 sets the required characteristics and classification; specific dimensional tables, test methods or torque values are defined in the full standard text.)
Applications
- Mechanical and structural assemblies where vibration or dynamic loading can cause fastener loosening.
- Automotive, rail, and heavy equipment applications requiring reliable clamp force retention.
- Industrial machinery, plant engineering, and construction where flange nuts with integrated bearing face and lock insert improve assembly repeatability and maintenance.
- Procurement, quality control and specification: Used by purchasing agents to specify compliant fasteners, by manufacturers for product design and testing, and by inspection labs for conformity checks.
- Fastener and component manufacturers designing or producing prevailing-torque hexagon flange nuts.
- Design engineers specifying nuts for vibration‑resistant joints.
- Quality and compliance teams performing acceptance testing or supplier audits.
- Procurement specialists creating technical purchase specifications for nuts in property classes 8 and 10.
Related standards
Keywords: EN 1663:1997, prevailing torque nut, hexagon nut with flange, non‑metallic insert, ISO 7043, coarse threads M5–M20, product grade A/B, property class 8, property class 10, CEN standard.