Overview
EN ISO 7089:2000 (ISO 7089:2000) specifies the characteristics of plain washers - normal series - product grade A for metric fastenings. It covers nominal thread diameters from 1.6 mm to 64 mm and defines washers in two hardness classes (200 HV and 300 HV). The standard provides dimensional tables, material and hardness guidance, surface and workmanship requirements, designation format, and references to inspection and testing methods.
Keywords: plain washers, ISO 7089, product grade A, normal series, metric washers, hardness class, fasteners
Key topics and requirements
- Scope and sizes: Preferred and non-preferred nominal sizes and corresponding clearance hole, outside diameter and thickness are specified for nominal thread diameters 1.6–64 mm.
- Hardness classes: Washers are specified in 200 HV and 300 HV hardness classes. Hardness testing follows ISO 6507-1 with test forces depending on nominal thickness.
- Material and grades: Steel and stainless-steel options are covered, including common stainless grades A2 and A4. Material selection aligns with ISO 3506-1 for stainless fasteners.
- Mechanical suitability:
- 200 HV washers: suitable with hexagon bolts/screws (product grades A/B) up to property class 8.8, and hexagon nuts up to class 8; also for stainless components and case-hardened thread-rolling screws.
- 300 HV washers: suitable up to bolt property class 10.9 and nut class 10.
- Dimensional and tolerance control: Dimensions and tolerances are given (tables for preferred/non-preferred dimensions); tolerances apply before plating/coating per ISO 4759-3.
- Surface finish & workmanship: Plain finish expected for product grade A; plating/coating guidance provided (avoid hydrogen embrittlement; follow ISO 4042 and ISO 10683 where applicable). Parts must be free of burrs and detrimental defects.
- Acceptance & testing: Acceptance inspection referenced to ISO 3269.
Applications
- Used as general-purpose plain washers in bolted joints for machinery, automotive assemblies, construction and general engineering.
- Ensures consistent bearing surface, load distribution and spacing for hexagon bolts, screws and nuts within specified property classes.
- Useful in procurement, component specification, manufacturing drawings and quality control to ensure interchangeability and reliable assembly.
Who uses this standard
- Fastener manufacturers and suppliers
- Design and mechanical engineers specifying bolted joints
- Quality inspectors and testing laboratories
- Procurement specialists and standards committees
Related standards
Designation examples from the standard:
This standard ensures consistent, interoperable plain washers for metric fasteners, improving reliability and specification clarity in engineering and manufacturing.
