EN ISO 7090:2000 PDF

Overview

EN ISO 7090:2000 is an internationally recognized standard specifying the requirements for plain chamfered washers of the normal series, product grade A. These washers conform to precise dimensions and hardness classes designed to ensure compatibility and reliability in fastening applications. This standard covers washers with chamfered outer edges in nominal sizes ranging from 5 mm to 64 mm and focuses on two hardness classes: 200 HV and 300 HV.

Developed by ISO Technical Committee ISO/TC 2 (Fasteners) and adopted by CEN, EN ISO 7090:2000 aims to unify specifications for plain washers used in conjunction with bolts, screws, and nuts across various industries. It replaces the earlier ISO 7090:1983 with technical revisions to align with current mechanical and material requirements.

Key Topics

• Scope and Application The standard is applicable to chamfered plain washers predominantly used with bolts, screws, and nuts of product grades A and B. It specifies washers for property classes up to 8.8 and 10.9 depending on hardness class, including stainless steel and case-hardened thread rolling screws.

• Dimensions and Sizes Washers are defined by nominal thread diameters from 5 mm to 64 mm. Detailed preferred and non-preferred dimensional tables provide clearance hole diameter, outside diameter, and thickness tolerances enabling accurate manufacturing and consistent interchangeability.

• Material and Hardness Classes The standard covers washers made from steel and stainless steel, with hardness classifications of 200 HV and 300 HV. Washers in the 200 HV class suit use with lower property classes of fasteners, while 300 HV washers are designed to endure higher-grade fastener applications.

• Surface Treatment and Quality Control Recommendations include protective lubricants or specific coatings to prevent corrosion and hydrogen embrittlement, referencing related ISO standards such as ISO 4042 (electroplated coatings) and ISO 10683 (non-electrolytically applied zinc flake coatings). Acceptance inspection follows ISO 3269 guidelines.

• Designation A clear coding system is provided for identification, including nominal size, hardness, and material grade to facilitate order accuracy and traceability. For example: Washer ISO 7090-8-200 HV-A2 describes a chamfered plain washer, size 8 mm, 200 HV hardness, and A2 stainless steel.

Applications

EN ISO 7090:2000 plain chamfered washers are critical components in numerous mechanical and structural fastening applications:

• Machine Assembly Used for distributing load and preventing damage to surfaces when tightening bolts and nuts, especially in applications requiring high durability or exposure to stress.

• Automotive and Aerospace Suitable for fastening components where high mechanical strength and corrosion resistance for stainless steel washers are essential.

• Construction and Engineering Provide reliable load distribution and protection against loosening in steel structures, bridges, and heavy machinery.

• General Industrial Use Serve as standard fastener components in general manufacturing, equipment maintenance, and repair works, ensuring interchangeability and safety.

Related Standards

• ISO 887:2000 - Plain washers for metric bolts, screws, and nuts general plan
• ISO 3269:2000 - Fasteners acceptance inspection
• ISO 3506-1:1997 - Mechanical properties of corrosion-resistant stainless-steel fasteners
• ISO 4042:1999 - Fasteners electroplated coatings
• ISO 4759-3:2000 - Tolerances for plain washers product grades
• ISO 6507-1:1997 - Vickers hardness test method
• ISO 10683 - Fasteners non-electrolytically applied zinc flake coatings

By adhering to EN ISO 7090:2000, manufacturers and users can ensure uniform product quality, compatibility, and enhanced performance in fastened assemblies, contributing to higher reliability and safety of mechanical systems.