EN 2647:2006

Overview

EN 2647:2006 is a European standard that defines the specifications for aerospace series hexagonal nuts. These nuts are self-locking with ball seats, made from alloy steel, cadmium plated, and MoS2 (molybdenum disulphide) lubricated. The classification sets their mechanical capability at 900 MPa tensile strength at ambient temperature and a maximum service temperature of 235 °C. This standard ensures that the nuts meet stringent aerospace industry requirements regarding strength, durability, and corrosion resistance.

Developed by the European Committee for Standardization (CEN), EN 2647:2006 is crucial for manufacturers and users in aerospace and defense sectors who demand robust fastening solutions capable of withstanding challenging operating conditions. This standard harmonizes product characteristics, enabling compatibility with washers to EN 2648 and other suitable components.

Key Topics

• Self-Locking Hexagonal Nuts: Designed with a ball seat to provide reliable self-locking functionality under vibration and thermal fluctuations.
• Material Composition: Nuts are made of alloy steel, offering excellent mechanical strength.
• Surface Treatment: Cadmium plating (minimum 5 µm thickness on threads and contact surfaces) provides corrosion resistance. MoS2 lubrication reduces friction for better tightening performance.
• Mechanical Classification: Rated for 900 MPa tensile stress at ambient temperature and able to withstand service temperatures up to 235 °C without permanent degradation.
• Dimension and Tolerance: Detailed dimensional tolerances and form specifications are provided, ensuring precise fit and uniformity. Metrics such as thread sizes, masses, and geometric measurements are specified according to ISO and EN standards.
• Assembly Guidance: Includes recommended assembly procedures for correct application with washers compliant with EN 2648.
• Marking and Identification: Nuts must be marked following EN 2424, which includes style, diameter codes, and manufacturer identification for traceability.
• Quality Assurance: Manufacturers must adhere to quality management systems specified in EN 2000 and qualification processes such as EN 9133 for standard parts.

Applications

EN 2647:2006 hexagonal self-locking nuts are primarily used in aerospace and defense industries where high reliability fastening is critical. Typical applications include:

• Aircraft structural assemblies requiring vibration-resistant fasteners.
• Engine mounts and components exposed to elevated temperatures.
• Aerospace mechanical joints needing corrosion-resistant, durable nut solutions.
• Space vehicles and missile systems where consistent performance under thermal cycling is essential.
• High-performance machinery where standards-based, quality assured nuts improve assembly safety and maintenance.

By following this standard, manufacturers and maintenance teams ensure nuts perform consistently in extreme conditions, minimize loosening risks, and extend service life.

Related Standards

To fully comply and optimize fastening systems, EN 2647:2006 should be used in conjunction with the following related standards:

• EN 2648: Aerospace series washers - specifically concave alloy steel washers, cadmium plated, compatible with EN 2647 nuts.
• ISO 5855-2: Aerospace MJ threads - defines limit dimensions for bolts and nuts to ensure thread compatibility.
• ISO 5858: Aerospace self-locking nuts - provides procurement specifications for high-temperature resistant nuts.
• EN 2133: Cadmium plating of steels - outlines plating requirements to ensure corrosion protection.
• EN 2491: Molybdenum disulphide dry lubricants - covers coating methods to ensure consistent lubrication.
• EN 2424: Marking of aerospace products - standardizes markings for traceability.
• EN 2000 and EN 9133: Quality assurance and qualification of aerospace manufacturers and standard parts.

These related standards complement EN 2647:2006 by governing washers, threads, materials, coatings, and quality management to guarantee high-quality fasteners in aerospace assemblies.

Keywords: aerospace nuts, hexagonal self-locking nuts, ball seat nuts, alloy steel nuts, cadmium plated nuts, MoS2 lubrication, aerospace fasteners, EN 2647:2006, aerospace standards, high-strength nuts, vibration resistant nuts, aerospace assembly components.