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Bearing basics SKF
- 1. 2013-03-17 ©SKF Slide 1 WE 201 SKF Reliability Maintenance Institute Materials Used for SKF Rolling Bearings Bearing rings and rolling elements Through-hardening steels Carbon chromium steel containing approximately 1 % carbon and 1,5 % chromium Case-hardening steels Chromium-nickel alloyed steel and manganese-chromium alloyed steel containing approximately 0,15 % carbon
- 2. 2013-03-17 ©SKF Slide 2 WE 201 SKF Reliability Maintenance Institute Heat Treatments Advantages Bainitic hardening Tough structure Automatic dimensional stability Compressive residual surface stresses Case hardening Hard surface and soft core resists through cracking Highest compressive residual surface stresses Martensite hardening Less costly Fixture can be used to reduce distortion Disadvantages Bainitic hardening Somewhat more costly than martensite Lower hardness Case hardening Time consuming and costly process Martensite hardening Highest risk of propagation of surface cracks
- 3. 2013-03-17 ©SKF Slide 3 WE 201 SKF Reliability Maintenance Institute Heat treat and hardness Martensite-hardened material (through hardening) Bainite-hardened material (through hardening) Tensile stresses 50 – 100 MPa Compressive stresses 50 – 100 MPa Compressive stresses 200 – 400 MPa 60 HRC 60 HRC 59 HRC 35 HRC 59 HRC 58 HRC : Tensile stresses : Compressive stresses Case-hardened material
- 4. 2013-03-17 ©SKF Slide 4 WE 201 SKF Reliability Maintenance Institute Dimensional Stability Change in diameter (μm/100 mm) Holding time at 200 °C (392 °F) Hours Martensite Bainite
- 5. 2013-03-17 ©SKF Slide 5 WE 201 SKF Reliability Maintenance Institute Dimensional stability designation Stabilization Class Operating Temperature Hardness HRC SN S0 S1 S2 S3 S4 up to 120° C (248° F) 59 to 63 up to 150° C (302° F) up to 200° C (392° F) up to 250° C (482° F) up to 300° C (572° F) up to 350° C (662° F) 58 to 62 57 to 61 56 to 60 54 to 58 50 to 54
- 6. 2013-03-17 ©SKF Slide 6 WE 201 SKF Reliability Maintenance Institute The Principle SKF Rolling Bearing Range Ball bearings Roller bearings
- 7. 2013-03-17 ©SKF Slide 7 WE 201 SKF Reliability Maintenance Institute Ball and Roller Bearing Ranges Deep groove Ball bearings Roller bearings+ Angular contact Self-aligning Cylindrical Taper Needle Spherical
- 8. 2013-03-17 ©SKF Slide 8 WE 201 SKF Reliability Maintenance Institute Load Capabilities Load carrying capacity is expressed as the basic dynamic load rating
- 9. 2013-03-17 ©SKF Slide 9 WE 201 SKF Reliability Maintenance Institute Relative Speed Limitations Oil lubrication speed rating Grease lubrication speed rating Bearing speed limit r/min
- 10. 2013-03-17 ©SKF Slide 10 WE 201 SKF Reliability Maintenance Institute Bearing components Seal Rolling Elements Inner Ring Outer Ring Cage Seal
- 11. 2013-03-17 ©SKF Slide 11 WE 201 SKF Reliability Maintenance Institute Bearing terminology... Bore I.D. Bore Surface O.D. Surface Outside Diameter O.D.
- 12. 2013-03-17 ©SKF Slide 12 WE 201 SKF Reliability Maintenance Institute Bearing terminology Inner Ring Raceway Side Faces Outer Ring Raceway Inner Ring Land (Shoulder) Outer Ring Land (Shoulder)
- 13. 2013-03-17 ©SKF Slide 13 WE 201 SKF Reliability Maintenance Institute Catalog dimensions dD B
- 14. 2013-03-17 ©SKF Slide 14 WE 201 SKF Reliability Maintenance Institute Bearing terminology for a spherical roller bearing Outer Ring Cage Inner Ring Side Faces W33 Lubrication Groove and Hole Rolling Element Guide Ring Inner Ring Raceway
- 15. 2013-03-17 ©SKF Slide 15 WE 201 SKF Reliability Maintenance Institute Cage Variants Polyamide cage Window-type sheet steel cage Window-type solid brass cage
- 16. Pressed cages 2013-03-17 ©SKF Slide 16 WE 201 SKF Reliability Maintenance Institute + Lightweight + High strength + High vibration and acceleration resistance – Sensitive to poor lubrication + No operating temperature limit
- 17. Machined cages: brass 2013-03-17 ©SKF Slide 17 WE 201 SKF Reliability Maintenance Institute + Very high strength + Suitable for very high speed in connection with circulating oil – Relatively (very) expensive + Very high vibration and acceleration resistance
- 18. Molded cages: polyamide 2013-03-17 ©SKF Slide 18 WE 201 SKF Reliability Maintenance Institute + Lightweight + High elasticity + Good sliding properties + Good marginal lubrication properties – Operating temperature < +120 °C