Insert bearings are filled with one of the following greases:
zinc-coated and stainless steel insert bearings
→ food-grade grease GFJ
This grease fulfils the requirements listed in the Guidelines of section 21 CFR 178.3570 of the FDA (US Food and Drug Administration) regulations. It is approved by the USDA (United States Department of Agriculture) for Category H1 use (occasional contact with food stuffs).
all other insert bearings
→ standard grease VT307
The technical specifications for the various greases are listed in table 1.
Grease life for insert bearings
Grease life for insert bearings should be estimated according to the procedure described in this section. The grease life for insert bearings is presented as L10, i.e. the time period at the end of which 90% of the bearings are still reliably lubricated. When relubrication is required, the method to estimate relubrication intervals is described on under Estimating the relubrication interval for grease. For additional information, refer to Relubrication.
The grease life for insert bearings depends on the operating temperature and the speed factor. It can be obtained from diagram 1.
The grease life for each is valid under the following operating conditions:
- horizontal shaft
- very light to moderate loads (P ≤ 0,05 C)
- stationary machine
- low vibration levels
If operating conditions differ, the grease life obtained from the diagrams has to be adjusted:
- For vertical shafts, use 50% of the value from the diagram.
- For heavier loads (P > 0,05 C), use the reduction factor listed in table 2.
The values for adjusting the grease life are estimates. Vibration can have a negative influence on grease life. The extent cannot be quantified, and the influence increases with increasing operating temperature. For additional information, refer to Lubrication or contact the SKF application engineering service.