First, the inner and outer ring materials of precision bearings
We choose long-life high-carbon chromium bearing steel (GCr15) with ultra-high speed heat resistance, high load wear resistance and excellent stability, as well as top heat treatment technology and special stabilization treatment technology, coupled with mature grinding technology and professional assembly technology, In order to improve the heat resistance, wear resistance and burn resistance of the bearing, the service life of the precision bearing is 2-3 times higher than that of ordinary bearing steel technology, so that our products can meet the different special requirements of customers. (Table 1-Table 3)

2. The cage of the precision bearing
   We use ball-guided polyamide resin cages (codenamed by TN or TYN), commonly known as nylon cages; outer ring-guided phenolic resin cages (codenamed by TA), commonly known as bakelite cages; copper Cage (marked by M); and our latest double-guided PEEK cage, PEEK, as an emerging engineering plastic material, has been proven to have the best mechanical strength, dimensional stability and high temperature resistance among all known engineering plastics s material. PEEK has a long-term service temperature of 260°C, and has good corrosion resistance. It can still operate freely in a medium-strength acid-base corrosion environment, so it is generally used to make bearings that need to operate precisely in harsh environments.
3. Rolling elements of precision bearings
   Generally, if there is no special requirement, we choose steel balls made of high-carbon chromium bearing steel; Steel rolling elements cannot meet the requirements of working conditions. At this time, it is necessary to select rolling element materials with better performance. Among them, silicon nitride ceramic material is considered to be the most ideal rolling element material to replace bearing steel. The limit speed of silicon nitride ceramic ball (code name is represented by HQ1) is more than 1.2 times higher than that of bearing steel ball, and the service life is more than 2 times that of steel ball. It has been widely recognized in the fields of mechanical spindles and high-speed electric spindles. (Table 4)

Grade of bearing ball

Grade Ball diameter variation Spherical error Surface roughness Lot diameter variation
G3 0.08 0.08 0.01 0.13
G5 0.13 0.13 0.014 0.25
G10 0.25 0.25 0.02 0.5
G16 0.4 0.4 0.025 0.8

4. Sealing ring of precision bearing
   The sealing ring of precision bearings is mainly made of nitrile rubber. For high temperature environments, fluorine rubber and silicone rubber are also widely used. (table 5)
   Table 1
   Comparison table of bearing steel models in various countries:
   Country China Japan USA Germany France
   Bearing steel type (GB)GCr15 (JIS)SUJ2 (AISI)52100 (DIN)100Cr6 (NF)100C6
   Stainless Steel Type (GB)8Cr18 (JIS)SUS440C (AISI)440C (din)wnR4535 (NF)Z100CD17

Table 2
The inner and outer rings and steel balls of precision bearings are generally made of bearing steel (vacuum heat treatment). The chemical composition of high-carbon chromium bearing steel is shown in the following table:
Specification Grade Chemical Composition
C Si Mn S P Cr Mo
GB/T18254 GCr15 0.95-1.05 0.15-0.35 0.25-0.45 Below 0.025 Below 0.025 1.40-1.65
DIN 100Cr6 0.95-1.10 0.15-0.35 Below 0.50 Below 0.025 Below 0.025 1.30-1.60 Below 0.08
JIS G 4805 SUJ2 0.95-1.10 0.15-0.35 0.50 or less 0.025 or less 0.025 or less 1.30-1.60 0.08 or less
ASTM A 295 52100 0.98-1.10 0.15-0.35 0.25-0.45 Below 0.025 Below 0.025 1.30-1.60 Below 0.08

table 3
For special purposes, stainless steel materials with good corrosion resistance will be used, and the chemical composition is shown in the following table:
Specification Grade Chemical Composition
C Si Mn S P Cr Mo
GB/T3086 9Cr18 0.90-1.00 Below 0.80 Below 0.80 Below 0.030 Below 0.035 17.00-19.00
JIS G 4303 SUS440C 0.90-1.00 1.00 or less 1.00 or less 0.030 or less 0.040 or less 16.00-18.00 0.75 or less

Table 4
Comparison of the main properties of silicon nitride materials and bearing steel materials
Compared with angular contact ball bearings made of standard bearing steel with the same structure and size, hybrid ceramic angular contact ball bearings have the advantages of good high-speed performance, good rigidity, low friction and heat generation, and long life. High-precision imported hybrid ceramic ball bearings (code-named HQ1) can significantly improve the speed, rigidity, reliability and production efficiency of electric spindles, machine tool spindles, and mechanical spindles, and greatly reduce the friction and heat of the spindle and prolong the service life of the spindle.
Performance code and unit silicon nitride bearing steel
Density γ[ g⁄mm3 ] 3.2 7.8
Coefficient of thermal expansion α[1/℃] 20～1000℃ 3.2×10-6 —
20～300℃ — 11.8×10-6
Elastic modulus E[N/mm2] 3.15×105 2.08×105
Poisson’s ratio μ 0.26 0.3
Hardness HV10 1700 700
Stress intensity σB[N/mm2] 20℃ 700 2400
1000°C 700 0
Fracture toughness Kie[MN/m1.5] 7 25
Thermal conductivity λ[W/m℃] 30～40 40～50
Resistivity [Ωmm2/m] 1017～1018 0.1～1

table 5
Comparison table of performance parameters of sealing ring materials of precision bearings
Type Designation Temperature Range Hardness Shore A Advantages Disadvantages
Nitrile rubber NBR —40℃～120℃ 40～90 Low compression characteristics, high ductility Not suitable for high temperature conditions, and avoid direct sunlight and chemical erosion
high corrosion resistance
Excellent oil resistance
Fluorine rubber FKM/FPM —28℃～200℃ 50～95 High temperature resistance Not suitable for low temperature working conditions
Outstanding chemical resistance
Corrosion resistant to petroleum products
Silicone rubber MQ/PMQ/VMQ/PVMP —70°C～2000°C 25～80 Resistance to high temperature and dryness Poor surface wear and crack resistance
Resistance to sunlight and ozone aging
Cyanide NBR HNBR/NEM —35℃～165℃ 50～90 Heat resistance, high ductility Not suitable for ultra-low temperature conditions, avoid direct sunlight and chemical erosion
chemical corrosion resistance
Polypropylene rubber ACM/RUBBER —18℃～175℃ 40～90 Strong resistance to hot oil, sunlight and ozone erosion, and high crack resistance Poor waterproof performance, not suitable for ultra-low temperature working conditions