Lubrication Of Roller Bearings

1. Lubrication Of Roller Bearings

2. Roller Bearings have a long history 1794 around 700 BC 1869 40 AC around 3000 BC

3. Tasks of Roller Bearings lreducing friction ltransfer of loads lguiding rotating parts

4. Friction

5. Energy losses through friction „Although rolling friction is already very low, manufacturers of roller bearings and lubricants work continuously on further improvements..“ µ – 10 % = 1/2 E [AUS+BR+E+S] SKF — one of the world´s biggest manufacturers of roller bearings made the following calculation: If it can be managed to drop the friction in all roller bearings installed on the globe only by further 10%, the combined total electricity consumption of the countries Australia, Brasil, Spain und Sweden could be cut to a half !

6. Roller Bearings are named after the Shape of their rolling Elements spherical roller asymmetrical spherical roller symmetrical ball conical roller cylindrical roller needle roller

7. Friction in Roller Bearings lsmall portion of rolling friction lbut considerable share of sliding friction at: roller bearing rings cages and / or rolling elements against each other

8. Kinds of Lubricationof Roller Bearings 90% by greases 9,5% by oils 0,5% by solid lubricants only

9. The most important Parameters for selecting the suitable Lubricant revolution or DN - factor D + d 2 DN = ——— • n D = external bearing diameter [mm] d = internal bearing diameter [mm] n = revolution per minute [rpm] dm= medium bearing diameter [mm] = ——— D + d 2 temperature range

10. DN- Factors for OKS Bearing Greases

11. Temperature Range of OKS Bearing Greases with MoS2 with MoS2 + Mox - Active with MoS2 with Mox - Active with MoS2 + Mox - Active with PTFE with white solid lubricants with PTFE with PTFE

12. Lubrication by greases Grease pump Contamination may cause bearing failures. Seals protect to a large extent from outside contaminations. Frequent relubrication is required when the hazard of grease contamination exists. Same applies if the grease should seal also against penetrating moisture. Newly supplied grease pushes out both used up and contaminated grease through the labyrinth packing seals. Contamination penetrating through labyrinth channels.

13. Relubrication Intervals for Grease lubricated Roller Bearings Small bearings with lateral seals or cover plates do not need any relubrication. They are already for - life lubricated. For all other roller bearings relubrication intervals become valid.

14. Guidelines forRelubrication Intervalls tfc Lubrication interval, given by service hours 10 000 6 000 tfb 4 000 20 000 3 000 15 000 tfa 2 000 20 000 10 000 1 500 15 000 7 500 1 000 5 000 10 000 500 5 000 2 500 d=10 300 3 000 1 500 20 200 2 000 1 000 150 750 1 500 100 1 000 500 40 50 500 250 360 280 240 200 160 120 100 80 60 500 420 tfa = radial ball bearing tfb = cylindrical roller bearing / needle bearing tfc = self aligning roller bearing / taper rolling bearing / axial roller bearing massive cylindrical roller bearing (0,2 tfc), axial cylindrical roller bearing (0,5 tfc) 100 200 500 1 000 2 000 5 000 10 000 n [U/min] Example: A deep-groove ball bearing with an internal diameter d= 100mm running at a speed of n = 1000 rpm. The operating temperature lies between 60 and 70 °C. Which is the expected relubrication interval? The vertical in point n= 1000 rpm on the abscissa cuts the curve for d= 100mm. From there the horizontal leads to the outer left-hand scale (deep- groove ball bearings) indicating a relubrication interval of 10000 service hours

15. Correction of Relubrication Intervals The assessed intervals are valid only for: lbearings in stationary machines lnormal load lageing-proofed greases ltemperature < + 70°C at the outer ring

16. Dependance of Relubrication Intervals on Tempearture Lubrication interval °C labove 70°C the factor 0,5 applies for each temperature rise of 15°C i.e. with a temperature rise from e.g. 70°C up to 85°C the service life of the grease is cut by half. 100 85 70 lbelow 70°C the factor 2 applies for each temperature drop of 15°C i.e. with a temperature drop from e.g. 70°C down to 55 °C the service life of the grease is doubled. 55 40 Temperature at the outer ring

17. Lubrication by Oil is used at high speeds resp. at DN-factors exceeding 1.000.000 and in case heat conduction is necessary.

18. Oil bath lubrication Suitable only for bearings with low speeds. During stand-stills the oil level should not quite reach the middle of the rolling element at the bottom. .

19. Oil injection lubrication At high speed it becomes necessary, that the air turbulence circulating with the bearing is penetrated by the oil. This is ensured by injecting oil under high pressure (min.15 m/s) from the side into the bearing.

20. Circulatory oil lubrication Cooling pump With increasing speed the service temperature rises and accelerates the ageing of the lubricating oil. By circulatory lubrication the oil can be cooled and consequently the service temperature be reduced.

21. Lubrication with Solid Lubricants Deep groove ball bearings with increased clearance required at: lhigh temperatures > + 200 °C lhigh temperature variations llow speed

22. Lubrication with Solid Lubricants - Exsample Kiln-car bearings in the ceramics and brick industry Lubrication by Solid Lubricants only at temperatures > + 200 °C OKS 230 MoS2-High Temperature Paste (for thin-film lubrication during assembly and maintenance) in connection with OKS 310 MoS2-High-Temperature Lubricant (for relubrication during operation) The carrying fluid evaporates residue-free above 200°C and dry MoS2 films remain, which assure lubrication up to 450°C.

23. OKS Speciality Lubricants forRoller Bearings at: lHigh loads lShock stress lVibrations lLow or high speed lStop-and-go operation lVery low or very high temperatures lTemperature variations lHumid conditions lCorrosive influences lLong-term lubricating needs lUse in the food industry

24. Thank You for Your Attention