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