Overview
ISO 21950:2001 specifies requirements for coated abrasives - plain discs used on mobile and hand‑held grinding machines. The standard defines the nominal dimensions, tolerances and designation system for two disc types (Type A and Type B) and includes the conditions under which dimensional checks must be performed. It is intended to ensure interchangeability, consistent quality and correct identification of plain abrasive discs.
Key topics and requirements
- Scope: Plain discs for use on mobile and hand‑held grinding machines.
- Types: Two geometries are defined - Type A and Type B - with figures and a dimensional table (Table 1) specifying outside diameters, inside diameters and permissible deviations.
- Dimensions & tolerances: Nominal outside diameters and, for Type B, inside diameters are specified with limit deviations (see Table 1 and Figures 1–2 in the standard).
- Test conditions: Dimensional tolerances apply when discs are measured after storage for at least 24 hours at 20 °C ± 2 °C and relative humidity 65 % ± 5 %, in accordance with ISO 554.
- Designation: A compliant plain disc is designated by:
- the term “Plain disc”,
- the reference ISO 21950,
- type (A or B),
- outside diameter D (mm),
- and for Type B the inside diameter H (mm).
Example: Plain disc ISO 21950 B 115 × 22
- Marking: Discs must be marked with grain size and the manufacturer, supplier or registered trademark.
- Normative reference: ISO 554 (standard atmospheres for conditioning/testing).
Applications and who uses this standard
ISO 21950 is practical for:
- Manufacturers of coated abrasive plain discs - for product design, tooling and QA.
- Quality and test laboratories - to verify dimensional conformity under specified conditioning.
- Purchasing and specification engineers - to write unambiguous procurement and product specifications for discs used on mobile and hand‑held grinders.
- Distributors and suppliers - to ensure correct labelling and traceability.
- Regulatory and standards bodies - for harmonization of abrasive product requirements.
Typical applications include metalworking, fabrication, maintenance and on‑site grinding tasks where portable grinding tools are used.
Related standards
- ISO 554 - Standard atmospheres for conditioning and/or testing (referenced for test conditions).
- ISO 6344-1 / -2 / -3 - Coated abrasives - Grain size analysis (related for grain sizing and specification).
- Produced by ISO/TC 29 (Small tools), SC 5 (Grinding wheels and abrasives).
