Full Ceramic Bearings

Technology

Bearings and Balls are available in Si3N4, ZrO2 and Al203. In hybrid bearings and/or full ceramic. (Hybrids in P4 and P2. Full ceramic P6 and P5). Full Ceramic Radial ball bearings Full Ceramic Angular Contact bearings. Hybrid Small Ball Sealed Angular Contact bearings are also available.

SPECIALS:
We appreciate the opportunity to serve you with our standard product line as well as special requirements, so please send your “Specials” for price and delivery consideration. Special ball sizes and bearings are available if quantities warrant.

CERAMIC INFO:
Ceramic material, silicone nitride or Si3N4 retains strength and hardness up to 800c, as compared to bearings steel to only about 120c. The specific gravity of Si3N4 is 3.20g/cube as compared to 7.85g/cube cm for bearing steel. The obvious advantage of lighter weight equates to lower centrifugal forces. Reduced loading offers higher rotational speeds, less stress and will reduce the surfaces from damage.

Ceramic Bearing Advantages:

1. The coefficient of thermal expiation of Si3N4 is 0.0000032/k but that of bearing steel is 0.00001/k nearly a 1:4 ratio. Therefore Si3N4 ceramic bearings are more stable and reliable in a temperature variance condition.
2. The Si3N4 ceramic has double the hardness of bearing steel, and 1/3 modulus of elasticity larger than that of bearing steel, therefore the elastic deformation of Si3N4 is small under an identical loading.
3. Ceramic bearings can solve corrosion problems. Important to the Chemical industry, food industry and other highly contaminated applications.
4. The self lubricating qualities of ceramics lends itself to high vacuum applications where degassing from lubrications are a problem.
5. The non-magnetic advantages for electro-mechanical applications (and others) is another advantage of ceramic bearings. Metal flaking caused by wear from standard steel bearings is eliminated.
6. Affordable. The cost for hybrid bearings and now full ceramic bearings are now reasonably priced in comparison to specialty bearings normally used in severe applications.

Specialty Ceramic Materials are noted for their characters of high strength in high temperature, good wear ability, high rigidity, corrosion resistance, high temperature resistance, electrical insulation, non-magnetic, these characters qualify them for replacing steel to make bearing to meet the requirements in a severe condition where a steel bearing cannot withstand. Ceramic materials, which can be used in making bearings, include mainly silicon nitride (Si3N4), Zirconia (ZrO2), Alumina (Al2O3 ) and so on. Si3N4 is in speaking form, which bearing steel also had, But ZrO2, Al2O3 fail in a crush from, a catastrophic failure.

NOTE: NON-standard ceramic ball orders (and bearings) to specifications arranged by customers are welcome.

Table 1: Fundamental property data of ceramic and steel materials

Items		Unit	Bearing steel	Stainless steel	Si3N4 Silicon Nitride	ZrO2 Zirconia	AL2O3 Zirconia
	d Density	g/cm3	7.85	7.90	3.20-3.30	6.00	3.95
	Coefficient of Linear Expansion	10-6/k	10.0	11.0	3.2	10.5	8.5
	Young's Modulus	Gpa	208	200	300-320	210	380
	Psission's Ration	--	0.30	0.30	0.26	0.3	0.22
	HV Hardness HRC	-	700 62	66	1500-1800 75-80	1200 700	1800 80
	Bending Strength	Mpa	2400	2400	600-1200	950-1200	300-500
	Fracture Toughness	Mpam1/2	25	25	6.0-7.0	10.0	3.4
	Thermal Conductivity	W/mk	30-40	15	35	2-3	30
	Special Electrical Resistance	Ωmm2/m	0.1-1	0.75	1018	1015	1018
	Working Temperature	ºC	120	300	800	800	800
	Corrosion Resistance	-	poor	poor	good	good	good
	Stress Cycles (50% Failed)	-	107	107	107-109	105	105
	Non Lubrication Friction	-	large	large	little	little	little
	Magnetism	-	magnetic	magnetic	non-magnetic	non-magnetic	non-magnetic
	Centrifugal Force	-	very large	very large	little	large	middle
	Operate Temperature Increasing	-	high	high	low	low	low
	Size Stability	-	unstable	unstable	stable	stable	stable
	Conductivity	-	conductor	conductor	insulator	insulator	insulator
	Rolling Contact Failure Form	-	flanking	flanking	flanking	crush	crush

Table 2: Types of GSN200 ceramic balls

	Type		Dia. with zero gauge and preferred gauge		Type		Dia. with zero gauge and preferred gauge
	mm	inch	mm
					mm	inch	mm
	0.8	-	0.8000		7.5	-	7.5000
	1	-	1.0000		-	5/16	7.9375
	1.2	-	1.2000		8	-	8.0000
	1.5	-	1.5000		8.5	-	8.5000
	-	1/16	1.5875		-	11/32	8.7312
	2	-	2.000		9	-	9.0000
	-	3/32	2.3812		9.5	-	9.5000
	2.5	-	2.5000		-	3/8	9.5250
	3	-	3.0000		10	-	10.0000
	-	1/8	3.1750		-	13/32	10.3188
	3.5	-	3.5000
					11	-	11.0000
	-	5/32	3.9688
					-	7/16	11.1125
	4	-	4.0000
					11.5	-	11.5000
	4.5	-	4.5000
					-	29/64	11.5094
	-	3/16	4.7625
					-	15/32	11.9062
	5	-	5.0000
					12	-	12.0000
	5.5	-	5.5000
					-	31/64	12.3031
	-	7/32	5.5562
					-	1/2	12.7000
	-	15/64	5.9531
					13	-	13.0000
	6	-	6.0000
					-	17/32	13.4938
	-	1/4	6.3500
					14	-	14.0000
	6.5	-	6.5000
					-	9/16	14.2875
	-	17/64	6.7469
					15	-	15.0000
	-	-	7.0000
					-	19/32	15.0812
	-	-	7.1438
					-	5/8	15.8750

Table 3: Si3N4 Ceramic

Table 4: Grade of ceramic ball ISO3290-1975(E) STANDARD