Technical Overview of the EN ISO 7093 Standard: Large Series Plain Washers
The EN ISO 7093 standard regulates the geometric parameters and technical requirements for large series plain washers. This fastener is used to reduce contact pressure on mating parts and to bridge oversized mounting gaps. EV Group China offers expert assistance in selecting hardware according to the requirements of precision classes A and C.
EN ISO 7093-1: Large Series Plain Washers, Product Grade A
Operational Characteristics and Application
The first part of the standard covers product grade A washers with a hardness of 200 HV and 300 HV, designed for metric threads from M3 to M36. The use of these products is critical when assembling components made of soft materials or when dealing with enlarged holes where uniform distribution of clamping force is required.
Washers with a hardness of 200 HV are recommended by EV Group China for:
- Hexagon head bolts of product grades A and B with a property class not exceeding 8.8.
- Nuts of product grades A and B with a property class up to 8.
- Fasteners made of austenitic stainless steels.
- Case-hardened bolts.
Versions with a hardness of 300 HV are optimized for high-strength connections (bolts with a property class up to 10.9 and nuts up to class 10).
EN ISO 7093-2: Large Series Plain Washers, Product Grade C
Usage Specifics
The second part of the ISO 7093 standard defines the parameters for product grade C washers with a hardness of 100 HV. These elements are oriented towards use in general-purpose metal structures where wider production tolerances are acceptable.
Key application scenarios recommended by EV Group China engineers:
- Fixing parts with lower surface hardness to prevent deformation.
- Compensation for significant technological gaps in mounting holes.
- Use in pairs with bolts and screws of product grade C (property class up to 6.8).
- Use with nuts of product grade C (property class up to 6).
- Installation using case-hardened screws for working with polymer materials.
If you need to select sizes outside the scope of this standard, EV Group China specialists recommend referring to the basic ISO 887 standards.