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Technical
Producing Process
Bearings Material
Tolerance
 
Technical

►Producing Process:

Forging→Annealing→Turning work→Heat treating→Grinding→Measuring→Assembling→Testing→Clean Demagnetization oiled→Package

►Bearings   Material

 Rings(cups & cones) & Rolling elements
GEM bearing rings(cups), balls and rollers are made of GCr15.
This steel No. is equal to the AISI 52100(U.S.A.), DIN 100Cr6(Germany), JIS SUJ2(Japan) etc.
Chemical composition of GCr15 steel :
 
Steel No. Chemical composition( %) 
GCr 15  C Si Mn P S Cr Mo Cu Ni
0.95-1.05 0.15-0.35 0.25-0.45 ≤0.027  ≤0.02 1.40-1.65   ≤0.25 ≤0.30
 
 
Hardness
Hardness of bearing rings(cups & cones) & rolling elements is HRC60~HRC65.
 
Cages:
GEM standard bearing cages are made of cold rolled carbon steel. However, in cases of heavy duty, corrosive environment,misalignment and high speed operation, brass, stainless steel, nylon or phenolic resins will be used upon request.

Seals & Shields
GEM shields also employ carbon steel as standard.
Buna Nitrile is the standard and mostly common used material for GEM seals. Also, in order to meet the requirements of high temperature operation and compatibility with grease, a variety of other sealing materials are also applied to the seals.
 
Lubrication
Standard grease and oil are applied to GEM bearings
 
 
►Tolerance
GEM bearings' tolerance standard according to Chinese national standard GB/T307(equal to ISO492)
The followings are the contrast tables of Chinese national standard and the foreign standards.
 
Contrast of tolerance class for radial bearings in different countries(except tapered roller bearings.
 
Country Standard Tolerance Class
China  GB/T307 0(G) 6(E) 5(D) 4(C) 2(B)
ISO ISO492 0 6 5 4 2
Sweden SKF 0 P6 P5 P4 P2
Germany DIN 620/2 P0 P6 P5 P4 P2
USA ANSI B3.14 ABEC-1 ABEC-3 ABEC-5 ABEC-7 ABEC-9
Japan JIS B1514 0 6 5 4 2
 
 
Contrast of tolerance class for tapered roller bearings(metric size) in different countries  
 
Country Standard Tolerance Class
China  GB/T307 0 P6X   P5 P4  
ISO ISO492 0 6X   5 4  
Sweden SKF 0 CLN   P5    
USA ANSI  K   N C B A
Japan JIS  0 6X 6 5 4  

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