Bearings knowledge introduction

1. Ceramic Material Intro

Ceramic materials are mainly zirconia (ZrO2), silicon nitride (Si3N4), tantalum carbide (SiC) and alumina (Al2O3). For comprehensive performance and cost performance, ZrO2 and Si3N4 are suitable for bearing use.

1.1 Ceramic Characteristics

Materials 

Items

Zirconia Silicon Nitride Carbide Alumina
Chemical Formula ZrO2 Si3N4 SiC Al2O3
Density

(g/CM3

6 3.2 3.1 4
Thermal Expansion Coefficient

10-6/k

10.5 3.2 4.5 8.5
HV

Hardness

1100~1300 1400~1700 2000~2500 1800
HRC

Hardness

70~75 75~80 85~90 80
Highest temperature Resistance

450 800 1300 1000
Bending Strength

MPa

1000~1500 600~1000 450 300~500
Specific Resistance

Ωmm2/m

105~1015 108~1018 10~103 108~1018
Rotating Centrifugal Force Bigger Small Small Medium
Insulation Yes Yes No Yes
Acid and Alkali Resistant

Corrosion Resistance

Good Good Very Good Good

 

2. Ceramic Ball Specifications 

Deep groove ball ceramic bearings contain Si3N4 ceramic balls. Because of their excellent characteristics, they are suitable for high-speed operation, high temperature, insulation or chemical harsh circumstances, which can significantly improve bearing life and performance. The main use grades are as follows:

Grade VDS VV VDL RaRa max
G3 0.08 0.08 0.16 0.01
G5 0.13 0.13 0.25 0.014
G10 0.25 0.25 0.5 0.02

 Unit: µm

 

3.Ceramic Bearings

Depending on the conditions, all-ceramic bearings mainly made of ZrO2, Si3N4, SiC and also steel-ceramic hybrid bearings. Customers can have various choices based on their needs. TTN has designed steel-ceramic hybrid bearings and all-ceramic bearings for bicycle products for superior performance.

 

3.1 Steel-Ceramic Hybrid Bearings

Si3N4 ceramic balls are used in the steel-ceramic hybrid bearings. Since the ceramic density is only 40% of the steel ball, the centrifugal force generated by high-speed rotation can be suppressed, and the low friction resistance characteristics make the bearing overall high speed and long life. The specifications are as follows:

 

  • Bearing inner and outer rings: GCr15 or 440 stainless steel
  • Retainer: PTFE, nylon 66 (Nylon 66), PEI, PEEK, Graphite Nylon and other materials.
  • Ceramic balls: G5 grade Si3N4
  • Seal: Full contact (LLU), non contact (LLB) and general light contact design.
  • Grease: Kyodo Yushi PS2 or Kluber NB 52

 

3.2 Full Ceramic Bearings

Full ceramic bearings are oil-free, self-lubricating, high & low temperature resistant, especially on bicycles for more extreme performance, and are used in many professional drivers or top races. The inner and outer rings of the all-ceramic bearing designed by TTN are made of ZrO2, and the ceramic balls are made of Si3N4. The specifications are as follows:

 

  • Bearing inner and outer ring: ZrO2
  • Ceramic balls: G5 grade Si3N4
  • Retainer: PTFE, nylon 66 (nylon 66), PEI, PEEK, Graphite nylon and other materials.
  • Seal: Full contact (LLU), non contact (LLB) and general light contact design.
  • Grease: No lubrication or special grease lubrication. It can be adjusted according to customer needs.

 

4.Bearing Models

BEARING NO. ID(MM) OD(MM) W(MM) N/W(G)
608 8 22 7 10.8
699 9 20 6 6.8
609 9 24 7 12.8
R6 95 25 22 225 7 142 9.8
6000 10 26 8 17.1
6800 10 19 5 5.1
6900 10 22 6 8.8
6001 12 28 8 18.8
6801 12 21 5 5.8
6901 12 24 6 10.0
6802 15 24 5 6.7
6902 15 28 7 15.0
MR15267 15 26 7 11.8
MR 15268 15 26 8 13.5
6803 17 26 5 7.3
6903 17 30 7 15.3
MR 17287 17 28 7 12.9
MR 18307 18 30 7 16.7
6804 20 32 7 16.7
MR 24377 24 37 7 20.8
MR22378/11.3 22 37 8 32.80
6805 25 37 7 18.8
6805Z-N 25 37 6 15.7
6806 30 42 7 21.5
2019-11-26T11:19:45+00:00 September 20th, 2019|