Overview
ISO 10669:1999 defines the characteristics of plain steel washers of product grade A used in tapping screw and washer assemblies (per ISO 10510). Published by ISO and prepared by Technical Committee ISO/TC 2 (Fasteners), the standard covers both normal (Type N) and large (Type L) series, and is intended to ensure consistent dimensions, material properties and workmanship for industrial supply and interchangeability.
Key Topics
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Classification: Two types are specified:
- Type N - Normal series
- Type L - Large series
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Dimensions: Nominal thread sizes covered include washers for tapping screws with diameters from approximately 2.2 mm up to 9.5 mm. The standard provides clearance hole, outside diameter and thickness limits for each nominal size (see standard tables).
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Material and chemical limits: Washers are made of steel; the carbon content shall not exceed 0.12% unless otherwise agreed.
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Hardness and mechanical properties: A specified hardness class of 180 HV applies; the broader acceptable hardness range in the as-delivered condition is 180 HV to 300 HV. Hardness tests are to be performed according to ISO 6507-1 (Vickers method) with test forces dependent on nominal thickness.
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Tolerances and product grade: Dimensional tolerances are referenced to ISO 4759-3 for plain washers (product grades A and C). Note that product grade A does not apply to the tolerance of the clearance hole and thickness for these washers.
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Surface finish and coatings: Washers are supplied in a plain (natural) finish, possibly treated with a protective lubricant or coated as agreed between customer and supplier. Electroplating requirements are covered by ISO 4042. All tolerances refer to measurements prior to plating or coating.
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Workmanship and acceptance: Parts must be free of detrimental defects and protruding burrs. Acceptance inspection procedures follow ISO 3269.
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Designation example: Washer ISO 10669 - N - 4,2 - 180 HV
Applications
Plain washers specified by ISO 10669:1999 are used where tapping screws are paired with a washer to:
- Provide consistent bearing area and load distribution
- Maintain assembly reliability in sheet metal and thin-material fastening
- Support procurement specifications and quality control for fastener suppliers
- Facilitate interchangeability across manufacturers in industrial assembly
Typical users include fastener manufacturers, OEMs, procurement teams and quality laboratories that perform incoming inspection and hardness testing.
Related Standards
- ISO 10510 - Tapping screw and washer assemblies with plain washers
- ISO 4759-3 - Tolerances for plain washers (product grades)
- ISO 3269 - Fasteners - Acceptance inspection
- ISO 4042 - Fasteners - Electroplated coatings
- ISO 6507-1 - Vickers hardness test - Test method
For definitive dimensions, tables and procedural requirements consult the full ISO 10669:1999 document and the referenced ISO standards.
Open preview (PDF)Plain washers for tapping screw and washer assemblies — Normal and large series — Product grade A