SIST EN 4673-005:2010

Overview

SIST EN 4673-005:2010 is a European Standard developed by CEN that defines the specifications for aerospace-grade inserts with UNJ threads, featuring self-locking capabilities and self-broaching keys. This part 005 of the standard focuses specifically on inserts made from the heat-resisting nickel base alloy NI-P101HT (WASPALOY), which are silver plated for enhanced surface properties. The standard targets Inch series inserts used in critical aerospace applications requiring high tensile strength and temperature resistance.

Key attributes of these inserts include a tensile strength classification of 1,210 MPa and capability to withstand temperatures up to 760 °C without losing mechanical integrity. This ensures suitability for extreme aerospace environments where high mechanical and thermal performance is paramount.

Key Topics

• Material Specification

  • Inserts are manufactured from NI-P101HT (WASPALOY), a heat-resistant nickel base alloy.
  • Silver plating as per EN 2786 provides corrosion resistance and surface conductivity.
  • Self-broaching keys made from stainless steel or nickel alloy treated to hardness >600 HV ensure reliable mechanical locking.

• Design and Dimensions

  • The standard outlines normal, first repair, and second repair size inserts with precise tolerances.
  • Inserts feature UNJ thread forms in Inch series conforming to ISO 3161 for thread geometry.
  • Detailed dimensional charts specify internal/external thread diameters, lengths, and key groove parameters.

• Performance Characteristics

  • Self-locking function achieved by out-of-round key areas ensures vibration resistance.
  • Heat resistance up to 760 °C accommodates demanding aerospace engine and airframe conditions.
  • Minimum tensile strength of 1,210 MPa at ambient temperature guarantees mechanical reliability.

• Marking and Identification

  • Marking follows EN 2424 procedures with manufacturers' monograms according to TR 3198.
  • Product designation codes clearly identify size and repair class for traceability.

Applications

SIST EN 4673-005:2010 inserts are primarily used in aerospace fastener applications where secure thread retention under high load and temperature exposure is critical. Typical application areas include:

• Aerospace engine components exposed to elevated temperatures.
• Structural airframe joints requiring self-locking inserts that prevent fastener loosening due to vibration.
• Repair and maintenance operations where multiple insert sizes enable restoration of damaged threads.
• High-performance aircraft assemblies demanding nickel alloy fastener inserts with repairable and reusable designs.

By specifying high-grade materials and tight dimensional tolerances, this standard supports manufacturing of aerospace components with exceptional durability, repeatability, and compliance to stringent industry requirements.

Related Standards

• EN 4673-001: Installation and removal procedures for self-locking UNJ thread inserts.
• EN 4673-002: Design guidelines for inserts with self-broaching keys.
• EN 4673-003: Technical specifications covering broader insert characteristics.
• EN 2786: Electrolytic silver plating requirements for fasteners.
• EN 3220: Material specifications for NI-P101HT nickel base alloy in forged fasteners.
• EN 2424: Marking of aerospace products.
• ISO 3161: Thread form and limits for UNJ threads.
• TR 3198: Manufacturers’ identification monograms for aerospace products.

These interconnected standards provide a comprehensive framework for aerospace inserts, streamlining design, production, and quality assurance processes critical to aerospace fastener reliability.

By adhering to SIST EN 4673-005:2010, manufacturers and aerospace engineers can ensure the use of robust, heat-resistant, and corrosion-protected inserts offering self-locking thread security, which is essential for high-performance aerospace assembly and maintenance.