ISO 7093-1:2000

Overview

ISO 7093-1:2000 defines the requirements for plain washers - large series - product Grade A. The standard specifies dimensional ranges, material and hardness classes, surface finish considerations and designation rules for metric plain washers with nominal thread diameters from 3 mm to 36 mm. It covers two Vickers hardness classes (200 HV and 300 HV) and provides guidance on intended use with specified bolt and nut grades.

Key topics and technical requirements

• Size range and dimensions: Preferred and non-preferred nominal thread diameters from 3 mm to 36 mm with corresponding hole, outer diameter and thickness limits (dimensions given in millimetres in the standard).
• Hardness classes: Two hardness levels are specified - 200 HV and 300 HV - with hardness testing according to ISO 6507-1 (Vickers method).
• Compatibility with fasteners:
  • Washers 200 HV are suitable for hexagon bolts (grades A and B) up to quality class 8.8, and hexagon nuts up to class 8; also compatible with similar-composition stainless steel fasteners and certain self-tapping and case-hardened fasteners.
  • Washers 300 HV are suitable for higher-strength hexagon bolts up to class 10.9 and nuts up to class 10.
• Materials and grades: Covers carbon steel and stainless variants (references to A2, A4 grades where applicable) and allows agreement between supplier and purchaser for alternative metallic materials.
• Surface finish and coatings: No special finish required by default; electroplating and non‑electrolytic zinc lamellae coatings referenced (see ISO 4042, ISO 10683). Advises measures to prevent hydrogen embrittlement for quenched and tempered washers.
• Tolerances and quality: Dimensional tolerances and acceptance criteria referenced to ISO 4759-3 and inspection/reception per ISO 3269.
• Designation examples: e.g., "Rondelle ISO 7093-1-8-200 HV" or "Rondelle ISO 7093-1-8-200 HV-A2" for stainless.

Applications

• Used where larger bearing area is needed - for clamping onto soft metals, or where parts have oversized or clearance holes.
• Common in machinery assembly, structural connections and general engineering where standardized metric plain washers ensure predictable bearing, hardness and fit.
• Helps designers select washers matched to bolt/nut strength classes to avoid crushing or premature failure.

Who should use this standard

• Mechanical designers and engineers specifying fasteners and washers
• Fastener manufacturers and suppliers for product conformity
• Procurement and quality inspectors performing acceptance testing
• Maintenance and assembly teams needing standardized replacement parts

Related standards

• ISO 887 (metric plain washers general)
• ISO 4759-3 (tolerances for washers)
• ISO 3269 (acceptance inspection)
• ISO 6507-1 (Vickers hardness test)
• ISO 3506-1, ISO 4042, ISO 10683 (materials/coatings)

Keywords: ISO 7093-1, plain washers, large series, grade A, metric washers, 200 HV, 300 HV, Vickers hardness, washer dimensions, fastener compatibility.