Overview
ISO 7090:2000 specifies the requirements for plain chamfered washers, normal series, product grade A, mainly used with metric screws and nuts. This international standard defines dimensional, mechanical, and material characteristics for plain washers with chamfered outer edges, ensuring uniformity and reliability in fastening applications. These washers are designed for nominal thread diameters ranging from 5 mm to 64 mm and hardness classes of 200 HV and 300 HV.
The standard is crucial for manufacturers, suppliers, and engineers who require precision washers that meet consistent quality benchmarks for industrial and mechanical assembly purposes.
Key Topics
- Scope: ISO 7090:2000 covers plain washers with chamfered edges used in conjunction with screws, nuts, and bolts of various grades and mechanical classes.
- Material Hardness Classes: Two hardness classes are defined:
- 200 HV for screws and nuts up to quality class 8.8.
- 300 HV for higher quality classes up to 10.9.
- Dimensions: The washers are standardized with precise dimensions for nominal diameters from 5 mm to 64 mm, including hole sizes, outer diameters, and thicknesses. Both preferred and non-preferred dimensions are included, ensuring adaptability to multiple mechanical requirements.
- Materials and Finishes: The standard accommodates washers made from steel and stainless steel (grades A2, A4, C1, C4) with specifications for surface treatment, including electrolytic and non-electrolytic coatings as per associated ISO standards (e.g., ISO 4042, ISO 10683).
- Tolerance and Quality: Tolerances are governed by ISO 4759-3, and final product quality includes freedom from defects such as burrs or irregularities to ensure proper performance in applications.
- Designation System: The standard details a clear nomenclature for identifying washer specifications, including diameter, hardness, and material grade to facilitate correct selection and procurement.
Applications
ISO 7090:2000 plain chamfered washers are widely used in:
- Mechanical assemblies where uniform load distribution and secure fastening are critical.
- Automotive and aerospace industries requiring reliable, high-strength fastening components.
- Manufacturing and construction, especially when combining different material grades and hardness classes, ensuring compatibility with specific bolt and nut grades.
- Stainless steel applications, where corrosion resistance alongside mechanical strength is necessary.
- Equipment maintenance and repair for replacing washers according to international standards, maintaining consistency and safety.
By adhering to ISO 7090:2000, engineers guarantee that washers provide optimal performance, extend the service life of assemblies, and meet international quality and safety benchmarks.
Related Standards
ISO 7090:2000 works in conjunction with several other international standards to provide a comprehensive framework for fasteners:
- ISO 887:2000 – General purpose plain washers for screws and nuts, offering additional dimension selections.
- ISO 3269:2000 – Acceptance inspection for fasteners, including washers.
- ISO 3506-1:1997 – Mechanical properties of stainless steel fasteners, guiding material requirements.
- ISO 4042:1999 – Specifies requirements for electroplated coatings on fasteners.
- ISO 4759-3:2000 – Tolerances for flat washers, ensuring dimensional precision.
- ISO 6507-1:1997 – Vickers hardness testing method, applied to verify hardness classes.
- ISO 10683 (upcoming) – Non-electrolytic zinc flake coatings for fasteners, covering additional surface protection methods.
Conclusion
ISO 7090:2000 is an essential standard for ensuring the quality and compatibility of plain chamfered washers within mechanical and industrial fastening systems. It aligns with global requirements for material properties, dimensions, and durability, facilitating universal acceptance and efficient production. Utilizing washers conforming to this standard enhances assembly reliability, safety, and performance across diverse engineering applications.