SIST EN ISO 7051:2011

Overview

SIST EN ISO 7051:2011 is an international standard specifying the characteristics and dimensions of cross-recessed raised countersunk (oval) head tapping screws. Published by CEN and aligned with ISO 7051:2011, this standard covers thread sizes ranging from ST 2.2 to ST 9.5. It serves as a key reference for manufacturers, engineers, and quality professionals involved in the production and application of tapping screws with these specific head and thread designs.

This standard ensures consistent quality, compatibility, and interchangeability of tapping screws used in a broad range of fastening applications. It also updates and supersedes the earlier EN ISO 7051:1994 to reflect current industry requirements and technological advances.

Key Topics

• Scope and Definitions: SIST EN ISO 7051:2011 applies to tapping screws with cross-recessed raised countersunk (oval) heads, specifying dimensions, thread profiles, and acceptable tolerances for thread sizes ST 2.2 to ST 9.5.

• Dimensions and Head Types: Detailed dimensional requirements include parameters for head diameter, height, recess types (Types H and Z cross recesses), thread pitch, and nominal lengths. The oval raised countersunk head is designed for both aesthetic finish and functional performance.

• Material Specifications:

  • Steel tapping screws comply with ISO 2702.
  • Stainless steel variants adhere to ISO 3506-4 (grades A2-20H, A4-20H, A5-20H).
  • Mechanical properties and heat treatment classifications are included for strength and durability assurances.

• Tolerance and Quality Control: The standard mandates tolerances in line with ISO 4759-1 and acceptance inspection procedures as per ISO 3269 to maintain uniform product quality and reliability.

• Surface Coatings and Finishes: Specifications for electroplated coatings (ISO 4042), non-electrolytically applied zinc flake coatings (ISO 10683), and passivation treatments for corrosion resistance (ISO 16048) ensure products meet performance and longevity expectations in various environments.

• Designation System: EN ISO 7051 provides a clear naming convention facilitating precise ordering and identification of screws based on size, material, end type, and recess type.

Applications

Cross-recessed raised countersunk (oval) head tapping screws standardized by SIST EN ISO 7051:2011 are widely used in:

• Precision engineering and electronics assembly, where compact fasteners with clean countersunk finishing are required.
• Automotive and aerospace industries, ensuring reliable screw fastening with standardized thread and head characteristics.
• Metal fabrication and sheet metal industries, leveraging tapping screws to join thin metal sheets securely without pre-threading.
• Construction and machinery manufacturing, where fasteners with controlled dimensions and coatings provide durability and corrosion resistance.
• Appliance manufacturing, benefiting from standardized components that guarantee quality and interchangeability.

Related Standards

SIST EN ISO 7051:2011 is interconnected with several other international standards essential for understanding and applying tapping screw specifications:

• ISO 225 – Symbols and descriptions of fastener dimensions.
• ISO 1478 – Specifications for tapping screw threads.
• ISO 2702 – Heat-treated steel tapping screws and their mechanical properties.
• ISO 3506-4 – Mechanical properties of stainless steel tapping screws.
• ISO 4757 & ISO 7721-2 – Cross recess dimensions and gauging methods.
• ISO 4759-1 – Tolerances for fasteners.
• ISO 3269 – Acceptance inspection protocols.
• ISO 4042 – Electroplated coatings for fasteners.
• ISO 10683 – Zinc flake coatings for corrosion resistance.
• ISO 16048 – Passivation of stainless steel fasteners.

Compliance with SIST EN ISO 7051:2011 and these related standards ensures fasteners meet international levels of performance, quality, and safety.

By following SIST EN ISO 7051:2011, businesses and engineers can confidently specify and utilize cross-recessed raised countersunk tapping screws that meet rigorous dimension, mechanical, and finish standards, supporting longevity and reliability across numerous industrial applications.