Overview
EN ISO 6103:2014 - Bonded abrasive products: Permissible unbalances of grinding wheels as delivered - Static testing specifies maximum permissible unbalances for bonded abrasive grinding wheels in the as‑delivered condition. It applies to wheels with an outside diameter D ≥ 125 mm and maximum operating speed v ≥ 16 m/s. The standard defines how to measure intrinsic unbalance, how to calculate permissible unbalance, and a practical static test to decide acceptability. It excludes diamond, CBN and natural stone wheels, and certain specialised wheels (centreless control, lapping/disc, ball and glass grinding wheels).
Key topics and technical requirements
- Permissible unbalance (Ua): Defined in terms of wheel mass and a coefficient k that depends on wheel type, application and maximum operating speed. Table 1 in the standard provides k values for common bonded abrasive types and speed ranges.
- Intrinsic unbalance (Ui): The product of wheel mass and offset between centre of mass and bore axis. Measured statically.
- Measurement method: Use a balancing arbor through the bore, support on parallel bevelled guide-bars or rotating steel discs, let the wheel reach equilibrium, mark the high point, rotate 90° and affix a test mass at the mark to achieve balance. The introduced mass m relates to unbalance by U = m · r (r = wheel radius).
- Acceptance criterion: A wheel is acceptable if Ui ≤ Ua. The practical acceptance test uses the calculated test mass ma = Ua / r; if the wheel remains stationary or rotates with the mark at the bottom after placing ma, it passes.
- Illustrative example: For a precision grinding wheel D = 762 mm, mass 68 000 g, v = 60 m/s, k = 0.32 and the permissible test mass ma is 83 g (as given in the standard).
Practical applications
- Quality control at abrasive manufacturers and grinding wheel suppliers: ensure wheels meet unbalance limits before shipment.
- Machine tool builders, maintenance and safety engineers: verify wheels will not induce excessive vibration, bearing wear or arbor stress when installed.
- End users (workshops, precision grinding shops): acceptance testing on incoming wheels to protect machine accuracy and operator safety.
- Useful for procurement specifications, inspection protocols, and product certification related to bonded abrasive products.
Related standards
- ISO 603 series (dimensions for bonded abrasive products) - listed in the standard’s bibliography.
- ISO/TC 29 (Small tools) technical context.
Keywords: EN ISO 6103:2014, ISO 6103, bonded abrasive products, grinding wheels, permissible unbalance, static testing, unbalance measurement, balancing arbor, wheel acceptance.
