Installing Hybrid Bearings
To obtain the best possible performance of the bearings, installation must be performed very carefully in ultra clean conditions.
Errors during fitting of ball bearings can jeopardize the best design and create high repair and maintenance costs. We would like to give some advise for proper mounting of bearings:
The workshop should be dust free with low humidity, no compressed air or machining is allowed.
Only unpack bearings immediately before installation. If grease is required it should be applied at this time, with a syringe. Do not use fingers or a spatula.
The use of a syringe is recommended to inject the grease right between the balls into the ball/raceway area. Nearly all standard greases are compatible to our rust preventive, so in most cases it is not necessary to wash the bearings prior to greasing. The only exceptions are special greases, based on silicone or fluorocarbon oils or PTFE-thickeners. They require a clean oil free surface to obtain good adhesion of the grease.
Never clean the bearings in ultra sonic devices! Allow the rust preventive to dissolve in a gasoline bath by slowly moving the bearings.
It is recommended to use filtered cleaning gasoline type 100/140 (max. filter 0.45 microns). Drying of the bearings should take place under a dust cover. Bearings should never be dried by blowing with compressed air because of environmental dust and moisture!
Finally the bearings, ready for installation, can be mounted by adequate means. It is of utmost importance to avoid misalignment of the bearings in the seats and that mounting loads never be applied through the balls.
The following pictures illustrate the correct installation:
The red lines show the line of force while pressing the bearings onto their seats.
The sketch on the right shows the mounting forces passing through the balls. This leads to indentations in the raceways hence the bearings run noisy and the service life will be reduced. This sketch shows the correct mounting of a bearing with a tight bore fit onto the shaft.
Mounting forces are conveyed through the inner ring only, balls and races remain free and undamaged. Very few applications call for tight fits on both bearing seats. In this case a bearing can be mountedim by pressing both rings simultaneously. As a result, balls and raceways remain undamaged.
In general, there are no particular running-in specifications for oil lubed bearings, nevertheless it proved advantageous when
- lubricant is available prior to start up. Consider length of feed pipes to avoid insufficient lubrication,
- when performing a short running-in procedure to allow the bearings to settle in their seats.
Grease lubrication calls for running-in of the bearings. Even when a reduced grease pack is applied to the bearing, a certain amount of surplus grease causes additional friction. A complete grease film must cover all contact surfaces.
GMN recommends the following procedure for the majority of applications:
- Starting sequence at 10 per cent of operating speed followed by a stop to allow the bearings to cool off to ambient temperature.
- Distribution sequence at 50 per cent of operating speed where actual operating temperature slightly exceeds final operating temperature. When the temperature has reached a maximum, the unit is stopped to cool off again to ambient temperature. Test sequence, first operate at nominal speed. If target operating temperature is exceeded, the distribution sequence should be repeated.
- Length and number of sequences depend on specific properties of the application. Grease reservoirs, limited space, operating speed and environmental media have a strong effect on the distribution of the grease.
How long and how often this procedure is to be repeated depends on the properties of the application. To optimize the running-in process for your specific application, please contact our application engineers.