ISO 3302-2:2022

Overview

ISO 3302-2:2022 - Rubber - Tolerances for products - Part 2: Geometrical tolerances defines geometrical tolerance requirements for moulded and extruded solid rubber products (including items with metal inserts). The standard is primarily for vulcanized rubber but is also suitable for many thermoplastic rubbers. It specifies how to measure and control flatness, parallelism, perpendicularity, coaxiality and positional tolerances to ensure consistent part fit and function.

Key topics and technical requirements

• Scope and product types: Applies to moulded and extruded solid rubber products, with examples for items containing metal inserts and mandrel‑supported extrusions.
• Tolerance classes: Three classes are defined - P (Precision), M (Medium) and N (Non‑critical). Higher classes (P, M) may require additional manufacturing/finishing (e.g., grinding).
• Geometrical tolerances covered:
  • Flatness tolerance (surface contained between two parallel planes)
  • Parallelism tolerance (sandwich structures and extruded cut sections)
  • Perpendicularity tolerance (faces perpendicular to an axis)
  • Coaxiality tolerance (moulded and mandrel‑supported extrusions; distinction between fixed and closure dimensions)
  • Positional tolerance (e.g., metal insert location - agreed between parties)
• Measurement rules:
  • Measurements after minimum 16 hours post‑vulcanization (extended to 72 hours if disputed); completion within 3 months after dispatch or before use.
  • Measurements at standard temperature after conditioning per ISO 23529; avoid distortion during measurement.
  • Instruments must be capable of measurement error within the specified tolerances; comparative measurements should use the same device.
• Special cases: Rotating parts are controlled by circular run‑out tolerances (per ISO 1101) rather than coaxiality; several tolerance tables by nominal dimension and class are provided.

Practical applications

• Ensures reliable interchangeability and function of rubber components used in:
  • Seals, gaskets, bushings and vibration mounts
  • Automotive and aerospace rubber parts
  • Industrial machinery, hydraulics and plumbing products with metal inserts
  • Extruded profiles and lathe‑cut rings
• Useful for setting supplier specification limits, production QC, inspection procedures and design tolerancing to avoid assembly issues.

Who should use this standard

• Rubber product designers and engineers
• Manufacturers of moulded and extruded rubber parts
• Quality control and metrology laboratories
• Procurement/specification writers and OEMs requiring consistent dimensional performance

Related standards

• ISO 1101:2017 - Geometrical product specifications (GPS) - geometrical tolerancing
• ISO 23529 - Rubber - conditioning and preparation of test pieces for measurement

Keywords: ISO 3302-2:2022, rubber tolerances, geometrical tolerances, flatness tolerance, parallelism tolerance, coaxiality, perpendicularity, positional tolerance, vulcanized rubber, moulded rubber, extruded rubber, ISO 1101, ISO 23529.