ISO 7093-2:2000

Overview

ISO 7093-2:2000 specifies plain washers - large series - Part 2: product grade C. It defines the dimensional, material and hardness characteristics for large-series plain (flat) washers of grade C with a nominal thread diameter range 3 mm to 36 mm and a hardness class of 100 HV. The standard is intended for washers used where bolts or nuts bear on soft metal parts or where oversized clearance holes require a larger washer face.

Key topics and technical requirements

• Scope and range: Covers plain (flat) washers, large series, grade C, nominal thread diameters from 3 mm to 36 mm inclusive.
• Hardness: Washers are specified as 100 HV (Vickers). Hardness testing follows ISO 6507-1, with HV10 test load for nominal thicknesses 0.6–1.2 mm and HV30 for thicker washers.
• Dimensions: Preferred and non‑preferred dimensions (bore diameters, outside diameters, and thicknesses) are given in the standard (see Tables 1 and 2 and Figure 1). Designers should select dimensions from ISO 887 when alternate sizes are needed.
• Material and finish: Typical material is steel; other metallic materials may be used by agreement. Surface conditions include supplied “as manufactured,” with protective lubricant, or with coatings per ISO 4042 (electrolytic) or ISO 10683 (non‑electrolytic zinc flake).
• Compatibility: 100 HV washers are suitable for use with hexagon bolts of grade C up to property class 6.8, hexagon nuts grade C up to class 6, and certain self‑tapping or case‑hardened screws (per the standard text).
• Tolerances and acceptance: Dimensional tolerances reference ISO 4759-3; reception and inspection follow ISO 3269. Parts must be free of burrs and harmful defects.

Applications and users

• Who uses it: Fastener manufacturers, mechanical design engineers, purchasing/procurement teams, quality/inspection personnel, and maintenance engineers.
• Typical applications: General engineering assemblies where a larger bearing surface is needed - protecting soft mating materials, distributing clamping loads over oversized holes or clearances, and standardizing washer supply for production lines.
• Benefits: Ensures interchangeability, consistent mechanical performance (hardness and dimensions), and proper coating/inspection practices across international supply chains.

Related standards

• ISO 7093-1 (Part 1: Grade A)
• ISO 887 (flat washers - general plan)
• ISO 4759-3 (tolerances for washers)
• ISO 4042 (electrolytic coatings)
• ISO 10683 (non-electrolytic zinc flake coatings)
• ISO 3269 (acceptance inspection)
• ISO 6507-1 (Vickers hardness test)

Keywords: ISO 7093-2, plain washers, large series, product grade C, 100 HV washer, metric washers, fastener standards, washer dimensions, ISO washer specification.