After mounting a bearing, the prescribed lubricant is applied and a test run made so that noise and bearing temperature can be checked.
The test run should be carried out under partial load and - where there is a wide speed range - at slow or moderate speed. Under no circumstances should a rolling bearing be allowed to start up unloaded and accelerated to high speed, as there is a danger that the rolling elements would slide on the raceways and damage them, or that the cage would be subjected to inadmissible stresses. Reference should be made to the section "Minimum load" in the relevant product section.
Any noise or vibration can be checked using an SKF electronic stethoscope. Normally, bearings produce an even "purring" noise. Whistling or screeching indicates inadequate lubrication. An uneven rumbling or hammering is due in most cases to the presence of contaminants in the bearing or to bearing damage caused during mounting.
An increase in bearing temperature immediately after start up is normal. For example, in the case of grease lubrication, the temperature will not drop until the grease has been evenly distributed in the bearing arrangement, after which an equilibrium temperature will be reached. Unusually high temperatures or constant peaking indicates that there is too much lubricant in the arrangement or that the bearing is radially or axially distorted. Other causes are that the associated components have not been correctly made or mounted, or that the seals have excessive friction.
During the test run, or immediately afterwards, the seals should be checked to see that they perform correctly and any lubrication equipment as well as the oil level of an oil bath should be checked. It may be necessary to sample the lubricant to determine whether the bearing arrangement is contaminated or components of the arrangement have become worn.