2.1 Materials for rings and rolling elements

while the contact surfaces between the bearing rings and rolling elements are subjected to repeated heavy stress,they must still maintain high rotational precession, therefore,the materials used for bearings rings and rolling
elements require the following characteristics:
· high rolling contact fatigue strength
· high hardness
· high wear resistance
· high dimensional stability
· high mechanical strength
The material used by our company is high carbon chromium bearings steel GCrl5-GB/T18254 equivalent such as AISI 52100(U.S.A), DIN 100Cr6(Germany)JIS SUJ2(Japan)and BS 534A99(U.K.). Its chemical composition is shown in table2.1. The stainless steel chemical composition is shown in table2.2

Table 2.1 High carbon chromium bearing steel

Standard	Trade mark	Chemical composition(%)
		C	Si	Mn	S	P	Cr	Mo
GB/T18254	GCr15	0.95-1.05	0.15-0.35	0.25-0.45	<=0.025	<0.025	1.40-1.65	-
ASTMA295	52100	0.98-1.10	0.15-0.35	0.25-0.45	<=0.025	<0.025	1.30-1.60	<0.10
JISG4805	SUJ2	0.95-1.10	0.15-0.35	0.50down	<=0.025	<0.025	1.30-1.60	<0.08

Table 2.2 Stainless steel

Standard	Trade mark	Chemical composition(%)
		C	Mn	Si	Cr	Ni	S	P	Mo
GB/T3086	9Cr18	0.90-1.0	<=0.80	<=0.80	17.0-1.90	<=0.3	<=0.03	<=0.035	<0.75
JISG4303	SUS4400	0.95-1.20	<1.0	<0.10	16.00-18.00	<0.6	<0.03	<0.004	-

2.2 Materials for cages
The materials for cages must have strength to withstand rotation at load and shock load.Low frictional efficiency light weight and be able to with stand operation temperature.
The material used in ribbon cages or crown cages is 08F or spec pressed

Its chemical composition is shown in table2.3 for extra-high speed application,plastic cages such as glass reinforced polyamide are used.These plastic crown cages have the advantages of low torque,long grease life and low noise,etc.

Table 2.3 Cage material purpose steel plane and chemical composition of carbon steel

Standard	Trade mark	Chemical composition(%)
		C	Si	Mn	S	P	Cr	Mo
GB/T699	08F	0.05-0.11	<=0.03	0.25-0.50	<=0.035	<=0.035	<=0.15	<=0.25
JISG3141	SPCC	<0.12	-	<0.5	<0.04	<0.045	-	-