ISO 32901 INTERNATIONAL STANDARD
ISO 32901:2014 STANDARD (STEEL BALLS) Precision grade Variation of ball diameter (VDws)(µm) (a) Deviation from spherical form (tDw)(µm) (a) Surface roughness (Ra)(µm) (a) Variation of ball lot diameter (VDwL)(µm) Gauge interval (IG) Description of preferred gauge Subgauge interval Description of subgauges (SG) 3 5/,+/+5 .