ISO 1940/1 is an international standard used for qualifying the balance of rotating rigid bodies. The standard also specifies the method for verifying residual imbalance. G0.4 is a particular balance grade within the overall standard. Compliance with this standard requires that the maximum residual imbalance falls within certain limits dependent on the overall mass of the rotating body. Grade G0.4 is on the finer end of the spectrum and typically the qualifying range for high speed precision spindles.

Some standard ISO grades and their applications are listed below:

G16 Drive shafts, engine components, engine crankshafts

  • G6.3 Marine main turbine gears, pump impellers, electric armatures
  • G2.5 Gas and steam turbines, turbo compressors, computer memory drums
  • G1 Grinding machine drives, small electric armatures, phonograph drives
  • G0.4 Gyroscopes, Spindles, precision grinders

This chart shows the specific amount of residual imbalance that is allowed for different ISO 1940/1 grades. Note that the graph is logarithmic. -ISO-1940-Graph_