Grease-packed sealed rolling bearings are probably the most widely used rolling bearings due to the ease of handling
and relatively long service life. However, grease will inevitably leak from such bearings because of the gap between
the seal and the inner race. This leakage causes the bearings to deteriorate prematurely and contaminates the
environment.

Reference Standard

JB/T 8571 – 2008

Rolling bearings – Sealed deep groove ball bearings – Performance test rule of dustproofing, grease leakage and temperature rise
Note: JB/T means Chinese industrial standard