Technical Data - Bearing Knowledge - KG Bearing India

Technical Data

Selecting the right bearing for a specific application requires a review of performance requirements and material operating limitations. Certain design considerations must be met in the device and bearing to address such factors as load, speed, temperature, environment, method of lubrication and fit. Often times sacrifices must be made in one area to satisfy another to achieve optimal life.

Many factors come into play when selecting a bearing or creating a new design in which a ball bearing will be employed. Most important are speed, load and temperature.

LOAD	SPEED	TEMPERATURE	ENVIRONMENT	SHAFT / HOUSING
Direction
Radial	Constant Variable	Average	Vacuum	Fits
Axial	Hi or Low	Max. Operating	Gas or Air	Geometry
Shock	dN> 250,000	Ambient	Contaminants	Tolerances
Combined				Mounting

BEARING DESIGN PROPERTIES THAT CAN BE MANIPULATED TO MEET CERTAIN PERFORMANCE CRITERIA ARE:

Other Properties

RADIAL INTERNAL CLEARANCE

CN
C3
C4

LOAD RATINGS

Basic Static
Basic Dynamic
Equivalent Dynamic “P”

MAXIMUM SPEED

Determined by size and design.

FITS

Shaft and Housing Fits

TOLERANCES

ABEC Class

BEARING LIFE

Basic Bearing Life
Ceramic Bearing Life

Part Number Properties

Example Part Number: CS6202XXPKWS – C | S | 6202 | XX | PK | WS

BALL MATERIAL: – C

C = Ceramic (Si3N4)
S = Stainless Steel (440C)
No symbol = Chrome Stee

RING MATERIAL – S

No symbol = Chrome steel
S = Stainless Steel (440C
S3 = Stainless steel (SS304)
C = Ceramic (Si3N4)
CR = Ceramic (ZrO2)
N = Nylon
P = PEEK

SIZE 6202

Basic size (see bearing size list)

CLOSURE XX

Gas or Air
Contaminants

RETAINER MATERIAL – PK

PK = PEEK
PS = PPS
VP1 = Vespel SP1
VP3 = Vespel SP3
TR = Torlon
PT = PTFE
NY = Nylon
PH = Phenolic
No symbol = Metal

LUBRICATION – WS

Dry film lubrication / Coating
WS = Tungsten Disulfide
MO = Moly Disulfide
Grease
L1 = SRI, General purpose
L2 = Poly Rex EM, Electric Motor grade
L3 = Krytox, High Temperature
L4 = LVP Krytox, Vacuum
L5 = Kluber NB52, High speed

BASIC STATIC LOAD RATING

The basic static radial load rating (Cor) applies to bearings which rotate at very slow speeds, subjected to very slow oscillations, or stationary under load. It should be considered when heavy shock loading occurs to a rotating bearing. The basic static radial load rating is defined as the static radial load which corresponds to a calculated contact stress at the center of the most heavily loaded ball/raceway contact of 609000 PSI for all radial and angular contact ball bearings. For this contact stress, a total permanent deformation of rolling element and raceway occurs which is approximately 0.0001 of the rolling element diameter. Basic Static Load Rating for stainless steel is 75 80% of that for standard bearing steel.

BASIC DYNAMIC LOAD RATING

The basic dynamic load rating (Cr) of a bearing with rotating inner ring and stationary outer ring is that load of constant direction and magnitude which a sufficiently large sample group of apparently identical bearings can endure for a basic rating life of one million revolutions.

Values given for (C) in the bearing size charts are for standard chrome steel. 80% to 85% of the chrome steel values should be used for stainless steel.

EQUIVALENT DYNAMIC LOAD RATING “P”

Typically load conditions on radial ball bearings are a combination of radial and axial loads. In order to establish the equivalent radial load with definite force and direction we use the following formula:

Cor/Fa	e	Fa/Fr≤e X	Fa/Fr≤e Y	Fa/Fr>e X	Fa/Fr>e Y
5	0.35	1	0	0.56	1.26
10	0.29	1	0	0.56	1.49
15	0.27	1	0	0.56	1.64
20	0.25	1	0	0.56	1.76
25	0.24	1	0	0.56	1.85
30	0.23	1	0	0.56	1.92
50	0.20	1	0	0.56	2.13
70	0.19	1	0	0.56	2.28

P=XFrYFa(kgf)
Fr=RADIAL LOAD(kgf) Fa=AXIAL LOAD(kgf)	X=RADIAL LOAD FACTOR Y=AXIAL LOAD FACTOR

For long term performance ball bearings must have some form of lubrication. Grease and oil is recommended whenever the application will allow it.

Generally grease is selected for low to medium speed applications and oil is selected for high speed applications.

Special environments such as vacuum, high and low temperatures may not allow conventional lubrication. In some applications the addition of grease or oil could contaminate a product. Many specialty lubrications are available to satisfy specific operating conditions.

For low speed low load applications or for when cleanliness and vacuum call for it a solid dry film lubricant coating such as Tungsten Disulfide or Moly Disulfide is a viable option.

Many specialty lubrications are available to satisfy specific operating conditions those listed below are our most common and are for comparison purposes only. There is no perfect lubrication and for specialty applications selection is made on a case by case basis. Data sheets should be analyzed for suitability.

MFG	BRAND	SPEED CAPABILITY	OPERATING TEMPERATURE
CHEVRON	SRI	LOW TO HIGH	-20 F to 305 F
EXXON	POLYREX-EM	LOW TO HIGH	-20 F to 350 F
DUPONT	KRYTOX	LOW TO MED	-50 F to 600 F
CASTROL	BRAYCOTE 601	LOW TO HIGH	-112 F to 400 F
KLUBER	ISOFLEX NB52	LOW TO HIGH	-58 F to 302F

SOLID LUBRICANTS

Solid lubricants offer excellent lubrication under extreme conditions.

When conditions exceed the limitations of wet lubricants as is found in high temperature vacuum applications, a dry solid lubricant coating can provide the boundary between rolling element and raceway reducing stress and increasing life.

These coatings are most beneficial to all steel bearings running dry where the boundary created by the coating can reduce micro-welding. For hybrid type bearings coatings can add additional life for critical applications.

Properties	Tungsten Disulfide (WS2)	Molybdenum Disulfide (MoS2)
Color	Silver Gray	Blue-Silver Gray
Appearance	Crystalline Solid	Crystalline Solid
Melting Point (º C)	1250º C	1185º C
Adhesion	Mechanical-molecular interlock	–
Density	7.4 grams/cc	5.0 grams/cc
Molecular Weight	248	160
Coefficient of Friction	0.03 – inclined plane technique	0.03 – inclined plane technique
Thermal Stability in Air	COF <0.1 till 1100ºF (594ºC)	COF <0.1 @600ºF (316ºC) increases to 0.5 @1100ºF (594ºC)
Thermal Stability in Argon	COF <0.1 till 1500ºF (815ºC)	COF increases rapidly starting @800ºF (426ºC) COF >0.1 @900ºF (482ºC)
Load Bearing Ability	Same as substrate to 350,000 PSI	to 250,000 PSI
Lubrication Temperature Range	Ambient: from -273ºC to 650ºC Vacuum(10-14 Torr): from -188ºC to 1316ºC	Ambient: from -185ºC to 350ºC Vacuum: from -185ºC to 1100ºC
Chemical Stability	Inert, non-Toxic	Inert, non-Toxic
Magnetism	Non-Magnetic	Non-Magnetic
Electrical Properties	Has Semiconductor properties	–
Rockwell Hardness	30HRc
Coating Film Thickness	0.5 micron	0.5 micron
Corrosion Resistance	Minor delay, will not inhibit	Minor delay, will not inhibit

Internal clearance is the play within a ball bearing. It is the geometrical clearance between the inner ring, outer ring and ball. It is a critical factor in bearing selection that will directly impact bearing life. It is often overlooked, particularly as to how it is reduced by interference fits.

Radial clearance is the play between the ball and raceway perpendicular to the bearing axis. Axial clearance is the play parallel to the bearing axis and is typically at least 10 times greater than the radial clearance. Generally, internal radial clearance will be reduced 80% of the interference fit amount.

Too little or too much internal clearance will significantly influence factors such as heat, vibration, noise, and fatigue life.

In extreme applications that see high or low temperatures this clearance needs to be considered in the overall design to compensate for thermal expansion and contraction of housings and shafts.

SELECTING BEARING CLEARANCE (GENERAL GUIDELINES)

Operating Condition	Clearance
Clearance fit on both inner and outer ring. Low to no axial loading. No preload. Low speeds. Little tolerance for play. Low temperature.	C2
Low torque. Standard loads. Light preload. Slight interference fit on inner or outer ring, not both. Low to medium speeds. Average temperature.	CN
Very low torque. High loads. Heavy interference fits. High temperature. Preloaded.	C3,C4,C5

DEEP GROOVE BALL BEARING RADIAL INTERNAL CLEARANCE (UNITS: ΜM)

Nominal Bore Diameter (mm)		Clearance
Nominal Bore Diameter (mm)		C2		CN (NORMAL)		C3		C4		C5
over	Incl.	min	max	min	max	min	max	min	max	min	max
10	18	0	9	3	18	11	25	18	33	25	45
18	24	0	10	5	20	13	28	20	36	28	48
24	30	1	11	5	20	13	28	23	41	30	53
30	40	1	11	6	20	15	33	28	46	40	64
40	50	1	11	6	23	18	36	30	51	45	73
50	65	1	15	8	28	23	43	38	61	55	90
65	80	1	15	10	30	25	51	46	71	65	105
80	100	1	18	12	36	30	58	53	84	75	120
100	120	2	20	15	41	36	66	61	97	90	140
120	140	2	23	18	48	41	81	71	114	105	160
140	160	2	23	18	53	46	91	81	130	120	180
160	180	2	25	20	61	53	102	91	147	135	200
180	200	2	30	25	71	63	117	107	163	150	230
200	225	2	35	25	85	75	140	125	195	175	265
225	250	2	40	30	95	85	160	145	225	205	300
250	280	2	45	35	105	90	170	155	245	225	340
280	315	2	55	40	115	100	190	175	270	245	370
315	355	3	60	45	125	110	210	195	300	275	410
355	400	3	70	55	145	130	240	225	340	315	460
400	450	3	80	60	170	150	270	250	380	350	510
450	500	3	90	70	190	170	300	280	420	390	570
500	560	10	100	80	210	190	330	310	470	440	630
560	630	10	110	90	230	210	360	340	520	490	690
630	710	20	130	110	260	240	400	380	570	540	760
710	800	20	140	120	290	270	450	430	630	600	840

The retainer keeps the balls equally spaced providing equal load distribution and prevents unnecessary wear of the rolling elements.

A retainer material with fillers can provide certain lubrication benefits as normal wear occurs. Numerous composite materials are available that are not listed here that can meet certain environmental and functional requirements.

Please contact us for further information.

PEEK and Vespel are generally considered vacuum compatible.

PPS offers the greatest chemical resistance and along with PEEK is FDA and USDA compliant.

PEEK and PPS offer the highest speed capability as a retainer material

Material compatibility in critical and or sensitive environments such as vacuum applications is subject to your bench testing and data sheet evaluation.

Since application environments vary greatly the following chart is simply a guideline.

RETAINER MATERIALS

Material	Max Temp	*Speed (dN)%**	Outgassing	Particle Generation	Cost
PEEK	480 F	650,000	Excellent	Excellent	Moderate
PPS	425 F	650,000	Good	Excellent	Moderate
VESPEL	500 F	600,000	Excellent	Excellent	High
TORLON	500 F	600,000	Excellent	Excellent	Moderate
TEFLON	550 F	30,000	Good	Good	Low
NYLON	250 F	250,000	Poor	Good	Low
PHENOLIC	300 F	600,000	Poor	Poor	Low

*d=inner bore diameter,N=RPM
%; Inner ring piloted, open configuration

RING AND BALL MATERIALS

CHROME STEEL

Chrome steel is one of a class of non stainless steels such as AISI 52100, En31, SUJ2, 100Cr6, 100C6, DIN 5401 which are used mostly in bearings

CERAMIC

Hybrid and full ceramic bearings are made using silicon nitride or zirconium oxide material.
Hybrid bearings are constructed of steel inner/outer rings, ceramic balls and retainers made of steel or thermoplastic.
Full ceramic bearings are 100% ceramic. Balls, rings and retainers.
The density of ceramic is 40% that of steel, the resulting reduction in weight reduces centrifugal forces imparted on the rings, reducing skidding, allowing up to 30% higher running speeds with less lubrication.
Silicon nitride balls have a 50 % higher modulus of elasticity (resistance to deformation) than steel, which increases rigidity and improving accuracy.
Ceramic balls have a smoother finish than steel, vibration and spindle deflection is reduced allowing higher speeds.
Ceramic has a lower coefficient of friction and is nearly twice as hard as bearing steel resulting in less wear with less lubrication. Bearing life can be increased.

Heat treated high carbon chromium bearing steel is the most common material used for rings and balls. Due to it low chromium content it exhibits poor corrosion resistance. The material does exhibit good mechanical properties up to 250F continuously. Above 250F bearing life is reduced as well as load capacity. Dimensional changes occur that require compensation in the overall bearing design and bearing fits. Applications are wide for this material. 52100 is magnetic.

440C STAINLESS STEEL

Heat treated 440C stainless steel offers fair to good corrosion resistance. It is the most common stainless steel used for rings and balls. With the addition of chromium and nickel corrosion resistance is greatly improved over 52100 steel. As oxygen reacts with the chromium a protective layer of chromium oxide is formed on the surface. This material can be passivated to improve corrosion resistance. Load capacity of 440C is about 20% less than that of 52100. With design considerations this material can handle service temperature up to 350F with fair load capacity. Beyond 350F capacity and life is reduced.

Applications may include some vacuum and clean processes or where general preventative corrosion resistance is desired. This material is magnetic.

300 SERIES STAINLESS STEEL (316 & 304)

In a semi-precision grade bearing, 300 series stainless steel can be chosen for improved corrosion resistance over 440C. These materials are not heat treated so load capacity is significantly less than HT 52100 & 440C. It can be used for both rings and balls or SS rings with ceramic balls. 300 series stainless steel offers excellent corrosion resistance to water and excellent to good resistance when exposed to certain common acids. This material can be an excellent choice for food grade applications. Other applications may include marine and vacuum processes. 300 series stainless steel is also a common material used for ribbon and crown type retainers. 300 series stainless steels are generally considered non-magnetic. As 300 series bearings are not as common as 440C, size availability and minimum order requirements apply.

PLASTICS

Numerous types of plastics can be used to produce semi-precision bearings.
Environment compatibility determines the variety. Acetal (Delrin) is the most common for the rings with balls of either acetal or stainless steel. Other Materials such as PEEK, PPS, Vespel, Nylon and many others can be used for the rings.

Lightly loaded low RPM applications requiring corrosion resistance, non-magnetic/non-metallic and or lightweight bearings may benefit from a plastic ball bearing. Sizes start at 8mm inner diameter. Minimum order requirements may apply.

CERAMIC MATERIAL PROPERTIES

Mechanical	SI/Metric	Si3N4	ZrO2
Density	gm/cc (lb/ft³)	3.29	6
Porosity	% (%)	0	0
Color	—	black	ivory
Flexural Strength	MPa (lb/in²x10³)	830	900
Elastic Modulus	GPa (lb/in²x10⁶)	310	200
Shear Modulus	GPa (lb/in²x10⁶)	—	—
Bulk Modulus	GPa (lb/in²x10⁶)	—	—
Poisson’s Ratio	—	0.27	—
Compressive Strength	MPa (lb/in²x10³)	—	—
Hardness	Kg/mm²	1580	1300
Fracture Toughness KIC	MPa•m^1/2	6.1	13
Maximum Use Temperature (no load)	°C (°F)	1000	1500

THERMAL

Thermal	SI/Metric	Si3N4	ZrO2
Thermal Conductivity	W/m•°K (BTU•in/ft²•hr•°F)	30	2
Coefficient of Thermal Expansion	10–6/°C (10^–6/°F)	3.3	10.3
Specific Heat	J/Kg•°K (Btu/lb•°F)	—	—

ELECTRICAL

Electrical	SI/Metric	Si3N4	ZrO2
Dielectric Strength	ac-kv/mm (volts/mil)	—	—
Dielectric Constant	—	—	—
Dissipation Factor	—	—	—
Loss Tangent	—	—	—
Volume Resistivity	ohm•cm	—	>10¹⁰

CERAMIC VS. STEEL VS. STAINLESS STEEL

Item	Ceramic, Si3N4	52100 Steel	440C
Density	.114 lb/in³	0.282lb/in³	0.275lb/in³
Service Temp	1300 F	300 F	350 F
CTE	1.56µin/in-°F	6.94µin/in-°F	5.67µin/in-°F
Hardness	~ 76 RC	62 RC	58 RC
Magnetism	No	Yes	YES
Conductivity	Non-conductive	Conductive	Conductive
Corrosion Resistance	Excellent	Poor	Fair

CORROSION RESISTANCE COMPARISON CHART

WATER

MATERIALS	316/304 Stainless Steel	440C Stainless Steel	52100 Chrome Steel
Stream	A	B	NC
Domestic Water	A	B	D
Sea Water	A	NC	D

FOOD

MATERIALS	316/304 Stainless Steel	440C Stainless Steel	52100 Chrome Steel
Food Products	A	B	NC
Fruit & Veg. Juices	A	B	NC
Dairy Products	A	C	NC

DILUTE ACIDS

MATERIALS	316/304 Stainless Steel	440C Stainless Steel	52100 Chrome Steel
HCL	—	NC	NC
H2SO4	B	NC	NC
HNO2	A	A	NC
Phosphoric	B	NC	NC

ACIDS

MATERIALS	316/304 Stainless Steel	440C Stainless Steel	52100 Chrome Steel
H2SO4	A	NC	NC
HNO2	NC	NC	NC
Phosphoric	A	NC	NC

MATERIALS	316/304 Stainless Steel	440C Stainless Steel	52100 Chrome Steel
Industrial Atmospheres	B	B	C
Salt Air	A	C	C
Ammonia	A	C	B
Alkaline Salts	B	B	C

A = excellent, B = good, C = fair, D = poor, NC = Not compatible

CHEMICAL COMPOSITION OF BEARING STEELS

Chrome Steel

Spec	C%	Si%	Mn%	P%	S%	Cr%	Mo%	Ni	N	Hard-ness
SAE52100 SUJ2	0.95-1.10	0.15-0.35	0.50max	0.025max	0.025max	1.30-1.60	–	–	–	60-64 HRC

Stainless Steel

Spec	C%	Si%	Mn%	P%	S%	Cr%	Mo%	Ni	N	Hard-ness
AISI440C SUS440C	0.95-1.20	1.00 max	1.00 max	0.04 max	0.03 max	16.0-18.0	0.75 max	–	–	58-62 HRC
AISI303 SUS303	0.15 max	1.0 max	2.00 max	0.2 max	0.15 min	18.0 – 20.0	0.6 max	9.0	0.1 max	83 HRB

To help retain bearing lubrication and prevent contamination from the environment a seal (contact) or shield (non-contact) can be employed.

Often no seal (Open) is required when the bearing will be housed and externally lubricated or when operated in a vacuum.

TYPES

‘Z’ Type Shield – The ‘Z’ type shield is a metal shield that typically is non-removable after installation as is it pressed in. There is a small gap about .005 inches between the shield and inner race. There is no contact so obtainable speeds and torque are not effected as in a contact type seal. Lubricant leakage can occur and contamination can enter through this gap. They have fair dust resistance and poor water resistance. Shields are good to around 350 F.

‘RS’ Type Seal – The ‘RS’ type seal is a rubber seal that makes contact with the inner race. Most commonly made of Buna-rubber. They are removable. They offer the best sealing against contamination and lubricant leakage. Generally the speed rating is reduced about 35% that of the ‘Z’ type or open and torque is increased. Temperature range is 15 F to 220 F.

‘V’ Type Seal – The ‘V” type seal is a non-contact type rubber seal that does not contact the inner race, but rides in groove machined in the inner races creating a labyrinth effect. Its performance falls between a metal shield and contact type rubber seal. Most commonly made of Buna-rubber. They are removable. They offer the good sealing against contamination and lubricant leakage. Generally the speed rating is not reduced and is comparable to that of the ‘Z’ type or open. There is no seal induced torque increase. Temperature range is 15 F to 220 F.

‘T’ Type Seal – The ‘T’ type seal is made of glass reinforced Teflon. This type of seal is removable and easily replaced. In most configurations the seal is held in place by a snap ring. The level of contact (sealing) can be adjusted to meet application requirements all the way from non-contact to heavy contact. Their best characteristic would be their high temperature capability of 500 F.

TYPE/MATERIAL	TEMP	SPEED CAPABILTY	TORQUE	AVAILABILITY
METAL SHIELD	350 F	GOOD	LOW	COMMON
RUBBER (CONTACT)	220 F	LIMITED	HIGH	COMMON
RUBBER (NONCONTACT)	220 F	GOOD	LOW	COMMON
TEFLON	500 F	GOOD	MED	COMMON
VITON	500 F	GOOD	MED	LIMITED

The ideal mounting for a precision bearing is line to line on both shaft and housing. Such a fit has no interference or looseness. For random fitting the fit tolerances may need to be increased to meet the lot variances. For selective fitting the bearing inner and outer diameter should be accurately measured, then the shaft and housing machined to suit.

Interference fits should be used with care as they can distort the raceway and reduce radial internal clearance. In preloaded pairs, reducing the internal radial clearance increases the preload. If excessive, the results can be significantly reduced speed capability and higher operating temperatures which will ultimately reduce life.

Some applications require interference fits such as:

Heavy radial loading
Intense vibration
Lack of axial clamping

Radial internal clearance is reduced by approximately 80% of the interference fit.

Interference fits are usually applied to the rotating ring.

Loose fits may be suggested when:

Axial clamping is possible, such a snap rings, locking collars or adhesive
Ease of assembly
Axial movement is required for spring preload or thermal movements

Fits are often overlooked and is arguably the most common bearing handling mistake.
The table below is simply a guideline as there are many influencing factors to be considered such as.

Load, speeds and temperatures
Ease of assembly and disassembly
Rigidity and accuracy requirements
Machining tolerances

Therefore the appropriate fit may fall somewhere in between.

ROTATING RING			INNER RING	OUTER RING
APPLICATION	DESIRED FIT TYPE	FIT(inches)	USE SHAFT DIAMETER	USE HOUSING DIAMETER
Low speed, or spring preload.	Loose	.0001L to .0005L	d – .0003 d – .0005	D .0001 D .0003
Medium speed	Line to Line	.0002L to .0002T	d – .0000 d – .0002	D – .0000 D – .0002
High speed	Light press	.0000 to .0004T	d .0002 d – .0000	D – .0002 D – .0004
High speed, high load	Tight press	.0002T to .0006T	d – .0002 d – .0004	D – .0004 D – .0006

STATIONARY RING			INNER RING	OUTER RING
Most applications	Line to line to loose	.0000 to .0004L	d – .0002 d – .0004	D – .0000 D .0002

L = Loose fit, T = Tight fit, d = Bearing I.D., D = Bearing O.D.

INNER RING TOLERANCE

ABEC 1 / ABEC 3
VALUES ARE IN .0001″

BORE DIAMETER				BORE TOLERANCE 0		RADIAL RUNOUT		WIDTH TOLERANCES 0
MM		INCH		ABEC 3	ABEC 1	ABEC 3	ABEC 1	ABEC 3	ABEC 1
OVER	INCL.	OVER	INCL.	ABEC 3	ABEC 1	ABEC 3	ABEC 1	ABEC 3	ABEC 1
0.6	2.5	.0236	.0984	-3	-3	2	4	-16	-16
2.5	10	.0984	.3937	-3	-3	2.5	4	-47	-47
10	18	0.3937	0.7087	-3	-3	3	4	-47	-47
18	30	0.7087	1.1811	-3	-4	3	5	-47	-47
30	50	1.1811	1.9685	-4	-4.5	4	6	-47	-47
50	80	1.9685	3.1496	-4.5	-6	4	8	-59	-59
80	120	3.1496	4.7244	-6	-8	5	10	-79	-79

INNER RING TOLERANCE

ABEC 5 / ABEC 7
VALUES ARE IN .0001″

BORE DIAMETER				BORE TOLERANCE 0		RADIAL RUNOUT (MAX.)		WIDTH VARIATION (MAX.)		REFERENCE RUNOUT WITH BORE (MAX.)
MM OVER	MM INCL.	INCH OVER	INCH INCL.	ABEC 7P	ABEC 5P	ABEC 7P	ABEC 5P	ABEC 7P	ABEC 5P	ABEC 7P	ABEC 5P
0	10	0	0.3937	-1.5	-2	1	1.5	1	2	1	3
10	18	0.3937	0.7087	-1.5	-2	1	1.5	1	2	1	3
18	30	0.7087	1.1811	-1.5	-2	1.5	1.5	1	2	1.5	3
30	50	1.1811	1.9685	-2	-2	1.5	2	1	2	1.5	3
50	80	1.9865	3.1496	-2	-3	1.5	2	1.5	2	2	3
80	120	3.1496	4.7244	-2.5	-3	2	2.5	1.5	3	2	3

OUTER RING TOLERANCE

ABEC 1 / ABEC 3
VALUES ARE IN .0001″

OUTER DIAMETER				OUTER DIAMETER TOLERANCE LIMIT 0		RADIAL RUNOUT		WIDTH TOLERANCES 0		FLANGE WIDTH TOLERANCE LIMITS 0		FLANGE DIAMETER TOLERANCE LIMITS 50
MM		INCH		ABEC 3	ABEC 1	ABEC 3	ABEC 1	ABEC 3	ABEC 1	ABEC 3	ABEC 1	ABEC 3	ABEC 1
OVER	INCL.	OVER	INCL.	ABEC 3	ABEC 1	ABEC 3	ABEC 1	ABEC 3	ABEC 1	ABEC 3	ABEC 1	ABEC 3	ABEC 1
0	18	0	0.7087	-3	-3	3	6	-47	-47	0	-47(2)	106(1)	-17(1)
18	30	0.7087	1.1811	-3	-3.5	4	6	-47	-47	0	-47	130	-20
30	50	1.1811	1.9685	-3.5	-4.5	4	8	-47	-47	0	-47	154	-24
50	80	1.9685	3.1496	-4.5	-5	5	10	-47	-47	0	-47	181	-29
80	120	3.1496	4.7244	-5	-6	7	14	-59	-59	0	-47	213	-34
120	150	4.7244	5.9055	-6	-7	8	16	-79	-79

OUTER RING TOLERANCE

ABEC 5 / ABEC 7
VALUES ARE IN .0001″

OUTER DIAMETER				OUTER DIAMETER TOLERANCE 0		RADIAL RUNOUT (MAX.)		WIDTH VARIATION (MAX.)		OUTSIDE CYLINDRICAL SURFACE RUNOUT WITH REFERENCE SIDE (MAX.)
MM OVER	MM INCL.	INCH OVER	INCH INCL.	ABEC 7P	ABEC 5P	ABEC 7P	ABEC 5P	ABEC 7P	ABEC 5P	ABEC 7P	ABEC 5P
0	18	0	0.7087	-2	-2	1.5	2	1	2	1.5	3
18	30	0.7087	1.1811	-2	-2	1.5	2	1	2	1.5	3
30	50	1.1811	1.9685	-2	-2	2	2	1	2	1.5	3
50	80	1.9685	3.1496	-2	-3	2	3	1	2	1.5	3
80	120	3.1496	4.7244	-3	-3	2	4	2	3	2	3
120	150	4.7244	5.9055	-4	-4	3	4	3	3	2	4

For long term performance ball bearings must have some form of lubrication. Grease and oil is recommended whenever the application will allow it.

Generally grease is selected for low to medium speed applications and oil is selected for high speed applications.

For low speed low load applications or for when cleanliness and vacuum call for it a solid dry film lubricant coating such as Tungsten Disulfide or Moly Disulfide is a viable option.

MFG	BRAND	SPEED CAPABILITY	OPERATING TEMPERATURE
CHEVRON	SRI	LOW TO HIGH	-20 F to 305 F
EXXON	POLYREX-EM	LOW TO HIGH	-20 F to 350 F
DUPONT	KRYTOX	LOW TO MED	-50 F to 600 F
CASTROL	BRAYCOTE 601	LOW TO HIGH	-112 F to 400 F
KLUBER	ISOFLEX NB52	LOW TO HIGH	-58 F to 302F

SOLID LUBRICANTS

Solid lubricants offer excellent lubrication under extreme conditions.

Properties	Tungsten Disulfide (WS2)	Molybdenum Disulfide (MoS2)
Color	Silver Gray	Blue-Silver Gray
Appearance	Crystalline Solid	Crystalline Solid
Melting Point (º C)	1250º C	1185º C
Adhesion	Mechanical-molecular interlock	–
Density	7.4 grams/cc	5.0 grams/cc
Molecular Weight	248	160
Coefficient of Friction	0.03 – inclined plane technique	0.03 – inclined plane technique
Thermal Stability in Air	COF <0.1 till 1100ºF (594ºC)	COF <0.1 @600ºF (316ºC) increases to 0.5 @1100ºF (594ºC)
Thermal Stability in Argon	COF <0.1 till 1500ºF (815ºC)	COF increases rapidly starting @800ºF (426ºC) COF >0.1 @900ºF (482ºC)
Load Bearing Ability	Same as substrate to 350,000 PSI	to 250,000 PSI
Lubrication Temperature Range	Ambient: from -273ºC to 650ºC Vacuum(10-14 Torr): from -188ºC to 1316ºC	Ambient: from -185ºC to 350ºC Vacuum: from -185ºC to 1100ºC
Chemical Stability	Inert, non-Toxic	Inert, non-Toxic
Magnetism	Non-Magnetic	Non-Magnetic
Electrical Properties	Has Semiconductor properties	–
Rockwell Hardness	30HRc
Coating Film Thickness	0.5 micron	0.5 micron
Corrosion Resistance	Minor delay, will not inhibit	Minor delay, will not inhibit

Too little or too much internal clearance will significantly influence factors such as heat, vibration, noise, and fatigue life.

In extreme applications that see high or low temperatures this clearance needs to be considered in the overall design to compensate for thermal expansion and contraction of housings and shafts.

SELECTING BEARING CLEARANCE (GENERAL GUIDELINES)

Operating Condition	Clearance
Clearance fit on both inner and outer ring. Low to no axial loading. No preload. Low speeds. Little tolerance for play. Low temperature.	C2
Low torque. Standard loads. Light preload. Slight interference fit on inner or outer ring, not both. Low to medium speeds. Average temperature.	CN
Very low torque. High loads. Heavy interference fits. High temperature. Preloaded.	C3,C4,C5

DEEP GROOVE BALL BEARING RADIAL INTERNAL CLEARANCE (UNITS: ΜM)

Nominal Bore Diameter (mm)		Clearance
Nominal Bore Diameter (mm)		C2		CN (NORMAL)		C3		C4		C5
over	Incl.	min	max	min	max	min	max	min	max	min	max
10	18	0	9	3	18	11	25	18	33	25	45
18	24	0	10	5	20	13	28	20	36	28	48
24	30	1	11	5	20	13	28	23	41	30	53
30	40	1	11	6	20	15	33	28	46	40	64
40	50	1	11	6	23	18	36	30	51	45	73
50	65	1	15	8	28	23	43	38	61	55	90
65	80	1	15	10	30	25	51	46	71	65	105
80	100	1	18	12	36	30	58	53	84	75	120
100	120	2	20	15	41	36	66	61	97	90	140
120	140	2	23	18	48	41	81	71	114	105	160
140	160	2	23	18	53	46	91	81	130	120	180
160	180	2	25	20	61	53	102	91	147	135	200
180	200	2	30	25	71	63	117	107	163	150	230
200	225	2	35	25	85	75	140	125	195	175	265
225	250	2	40	30	95	85	160	145	225	205	300
250	280	2	45	35	105	90	170	155	245	225	340
280	315	2	55	40	115	100	190	175	270	245	370
315	355	3	60	45	125	110	210	195	300	275	410
355	400	3	70	55	145	130	240	225	340	315	460
400	450	3	80	60	170	150	270	250	380	350	510
450	500	3	90	70	190	170	300	280	420	390	570
500	560	10	100	80	210	190	330	310	470	440	630
560	630	10	110	90	230	210	360	340	520	490	690
630	710	20	130	110	260	240	400	380	570	540	760
710	800	20	140	120	290	270	450	430	630	600	840

The retainer keeps the balls equally spaced providing equal load distribution and prevents unnecessary wear of the rolling elements.

Please contact us for further information.

PEEK and Vespel are generally considered vacuum compatible.

PPS offers the greatest chemical resistance and along with PEEK is FDA and USDA compliant.

PEEK and PPS offer the highest speed capability as a retainer material

Material compatibility in critical and or sensitive environments such as vacuum applications is subject to your bench testing and data sheet evaluation.

Since application environments vary greatly the following chart is simply a guideline.

RETAINER MATERIALS

Material	Max Temp	*Speed (dN)%**	Outgassing	Particle Generation	Cost
PEEK	480 F	650,000	Excellent	Excellent	Moderate
PPS	425 F	650,000	Good	Excellent	Moderate
VESPEL	500 F	600,000	Excellent	Excellent	High
TORLON	500 F	600,000	Excellent	Excellent	Moderate
TEFLON	550 F	30,000	Good	Good	Low
NYLON	250 F	250,000	Poor	Good	Low
PHENOLIC	300 F	600,000	Poor	Poor	Low

*d=inner bore diameter,N=RPM
%; Inner ring piloted, open configuration

RING AND BALL MATERIALS

CHROME STEEL

Chrome steel is one of a class of non stainless steels such as AISI 52100, En31, SUJ2, 100Cr6, 100C6, DIN 5401 which are used mostly in bearings

CERAMIC

Hybrid and full ceramic bearings are made using silicon nitride or zirconium oxide material.
Hybrid bearings are constructed of steel inner/outer rings, ceramic balls and retainers made of steel or thermoplastic.
Full ceramic bearings are 100% ceramic. Balls, rings and retainers.
The density of ceramic is 40% that of steel, the resulting reduction in weight reduces centrifugal forces imparted on the rings, reducing skidding, allowing up to 30% higher running speeds with less lubrication.
Silicon nitride balls have a 50 % higher modulus of elasticity (resistance to deformation) than steel, which increases rigidity and improving accuracy.
Ceramic balls have a smoother finish than steel, vibration and spindle deflection is reduced allowing higher speeds.
Ceramic has a lower coefficient of friction and is nearly twice as hard as bearing steel resulting in less wear with less lubrication. Bearing life can be increased.

440C STAINLESS STEEL

Applications may include some vacuum and clean processes or where general preventative corrosion resistance is desired. This material is magnetic.

300 SERIES STAINLESS STEEL (316 & 304)

PLASTICS

CERAMIC MATERIAL PROPERTIES

Mechanical	SI/Metric	Si3N4	ZrO2
Density	gm/cc (lb/ft³)	3.29	6
Porosity	% (%)	0	0
Color	—	black	ivory
Flexural Strength	MPa (lb/in²x10³)	830	900
Elastic Modulus	GPa (lb/in²x10⁶)	310	200
Shear Modulus	GPa (lb/in²x10⁶)	—	—
Bulk Modulus	GPa (lb/in²x10⁶)	—	—
Poisson’s Ratio	—	0.27	—
Compressive Strength	MPa (lb/in²x10³)	—	—
Hardness	Kg/mm²	1580	1300
Fracture Toughness KIC	MPa•m^1/2	6.1	13
Maximum Use Temperature (no load)	°C (°F)	1000	1500

THERMAL

Thermal	SI/Metric	Si3N4	ZrO2
Thermal Conductivity	W/m•°K (BTU•in/ft²•hr•°F)	30	2
Coefficient of Thermal Expansion	10–6/°C (10^–6/°F)	3.3	10.3
Specific Heat	J/Kg•°K (Btu/lb•°F)	—	—

ELECTRICAL

Electrical	SI/Metric	Si3N4	ZrO2
Dielectric Strength	ac-kv/mm (volts/mil)	—	—
Dielectric Constant	—	—	—
Dissipation Factor	—	—	—
Loss Tangent	—	—	—
Volume Resistivity	ohm•cm	—	>10¹⁰

CERAMIC VS. STEEL VS. STAINLESS STEEL

Item	Ceramic, Si3N4	52100 Steel	440C
Density	.114 lb/in³	0.282lb/in³	0.275lb/in³
Service Temp	1300 F	300 F	350 F
CTE	1.56µin/in-°F	6.94µin/in-°F	5.67µin/in-°F
Hardness	~ 76 RC	62 RC	58 RC
Magnetism	No	Yes	YES
Conductivity	Non-conductive	Conductive	Conductive
Corrosion Resistance	Excellent	Poor	Fair

CORROSION RESISTANCE COMPARISON CHART

WATER

MATERIALS	316/304 Stainless Steel	440C Stainless Steel	52100 Chrome Steel
Stream	A	B	NC
Domestic Water	A	B	D
Sea Water	A	NC	D

FOOD

MATERIALS	316/304 Stainless Steel	440C Stainless Steel	52100 Chrome Steel
Food Products	A	B	NC
Fruit & Veg. Juices	A	B	NC
Dairy Products	A	C	NC

DILUTE ACIDS

MATERIALS	316/304 Stainless Steel	440C Stainless Steel	52100 Chrome Steel
HCL	—	NC	NC
H2SO4	B	NC	NC
HNO2	A	A	NC
Phosphoric	B	NC	NC

ACIDS

MATERIALS	316/304 Stainless Steel	440C Stainless Steel	52100 Chrome Steel
H2SO4	A	NC	NC
HNO2	NC	NC	NC
Phosphoric	A	NC	NC

MATERIALS	316/304 Stainless Steel	440C Stainless Steel	52100 Chrome Steel
Industrial Atmospheres	B	B	C
Salt Air	A	C	C
Ammonia	A	C	B
Alkaline Salts	B	B	C

A = excellent, B = good, C = fair, D = poor, NC = Not compatible

CHEMICAL COMPOSITION OF BEARING STEELS

Chrome Steel

Spec	C%	Si%	Mn%	P%	S%	Cr%	Mo%	Ni	N	Hard-ness
SAE52100 SUJ2	0.95-1.10	0.15-0.35	0.50max	0.025max	0.025max	1.30-1.60	–	–	–	60-64 HRC

Stainless Steel

Spec	C%	Si%	Mn%	P%	S%	Cr%	Mo%	Ni	N	Hard-ness
AISI440C SUS440C	0.95-1.20	1.00 max	1.00 max	0.04 max	0.03 max	16.0-18.0	0.75 max	–	–	58-62 HRC
AISI303 SUS303	0.15 max	1.0 max	2.00 max	0.2 max	0.15 min	18.0 – 20.0	0.6 max	9.0	0.1 max	83 HRB

To help retain bearing lubrication and prevent contamination from the environment a seal (contact) or shield (non-contact) can be employed.

Often no seal (Open) is required when the bearing will be housed and externally lubricated or when operated in a vacuum.

TYPES

TYPE/MATERIAL	TEMP	SPEED CAPABILTY	TORQUE	AVAILABILITY
METAL SHIELD	350 F	GOOD	LOW	COMMON
RUBBER (CONTACT)	220 F	LIMITED	HIGH	COMMON
RUBBER (NONCONTACT)	220 F	GOOD	LOW	COMMON
TEFLON	500 F	GOOD	MED	COMMON
VITON	500 F	GOOD	MED	LIMITED

Some applications require interference fits such as:

Heavy radial loading
Intense vibration
Lack of axial clamping

Radial internal clearance is reduced by approximately 80% of the interference fit.

Interference fits are usually applied to the rotating ring.

Loose fits may be suggested when:

Axial clamping is possible, such a snap rings, locking collars or adhesive
Ease of assembly
Axial movement is required for spring preload or thermal movements

Fits are often overlooked and is arguably the most common bearing handling mistake.
The table below is simply a guideline as there are many influencing factors to be considered such as.

Load, speeds and temperatures
Ease of assembly and disassembly
Rigidity and accuracy requirements
Machining tolerances

Therefore the appropriate fit may fall somewhere in between.

ROTATING RING			INNER RING	OUTER RING
APPLICATION	DESIRED FIT TYPE	FIT(inches)	USE SHAFT DIAMETER	USE HOUSING DIAMETER
Low speed, or spring preload.	Loose	.0001L to .0005L	d – .0003 d – .0005	D .0001 D .0003
Medium speed	Line to Line	.0002L to .0002T	d – .0000 d – .0002	D – .0000 D – .0002
High speed	Light press	.0000 to .0004T	d .0002 d – .0000	D – .0002 D – .0004
High speed, high load	Tight press	.0002T to .0006T	d – .0002 d – .0004	D – .0004 D – .0006

STATIONARY RING			INNER RING	OUTER RING
Most applications	Line to line to loose	.0000 to .0004L	d – .0002 d – .0004	D – .0000 D .0002

L = Loose fit, T = Tight fit, d = Bearing I.D., D = Bearing O.D.

INNER RING TOLERANCE

ABEC 1 / ABEC 3
VALUES ARE IN .0001″

BORE DIAMETER				BORE TOLERANCE 0		RADIAL RUNOUT		WIDTH TOLERANCES 0
MM		INCH		ABEC 3	ABEC 1	ABEC 3	ABEC 1	ABEC 3	ABEC 1
OVER	INCL.	OVER	INCL.	ABEC 3	ABEC 1	ABEC 3	ABEC 1	ABEC 3	ABEC 1
0.6	2.5	.0236	.0984	-3	-3	2	4	-16	-16
2.5	10	.0984	.3937	-3	-3	2.5	4	-47	-47
10	18	0.3937	0.7087	-3	-3	3	4	-47	-47
18	30	0.7087	1.1811	-3	-4	3	5	-47	-47
30	50	1.1811	1.9685	-4	-4.5	4	6	-47	-47
50	80	1.9685	3.1496	-4.5	-6	4	8	-59	-59
80	120	3.1496	4.7244	-6	-8	5	10	-79	-79

INNER RING TOLERANCE

ABEC 5 / ABEC 7
VALUES ARE IN .0001″

BORE DIAMETER				BORE TOLERANCE 0		RADIAL RUNOUT (MAX.)		WIDTH VARIATION (MAX.)		REFERENCE RUNOUT WITH BORE (MAX.)
MM OVER	MM INCL.	INCH OVER	INCH INCL.	ABEC 7P	ABEC 5P	ABEC 7P	ABEC 5P	ABEC 7P	ABEC 5P	ABEC 7P	ABEC 5P
0	10	0	0.3937	-1.5	-2	1	1.5	1	2	1	3
10	18	0.3937	0.7087	-1.5	-2	1	1.5	1	2	1	3
18	30	0.7087	1.1811	-1.5	-2	1.5	1.5	1	2	1.5	3
30	50	1.1811	1.9685	-2	-2	1.5	2	1	2	1.5	3
50	80	1.9865	3.1496	-2	-3	1.5	2	1.5	2	2	3
80	120	3.1496	4.7244	-2.5	-3	2	2.5	1.5	3	2	3

OUTER RING TOLERANCE

ABEC 1 / ABEC 3
VALUES ARE IN .0001″

OUTER DIAMETER				OUTER DIAMETER TOLERANCE LIMIT 0		RADIAL RUNOUT		WIDTH TOLERANCES 0		FLANGE WIDTH TOLERANCE LIMITS 0		FLANGE DIAMETER TOLERANCE LIMITS 50
MM		INCH		ABEC 3	ABEC 1	ABEC 3	ABEC 1	ABEC 3	ABEC 1	ABEC 3	ABEC 1	ABEC 3	ABEC 1
OVER	INCL.	OVER	INCL.	ABEC 3	ABEC 1	ABEC 3	ABEC 1	ABEC 3	ABEC 1	ABEC 3	ABEC 1	ABEC 3	ABEC 1
0	18	0	0.7087	-3	-3	3	6	-47	-47	0	-47(2)	106(1)	-17(1)
18	30	0.7087	1.1811	-3	-3.5	4	6	-47	-47	0	-47	130	-20
30	50	1.1811	1.9685	-3.5	-4.5	4	8	-47	-47	0	-47	154	-24
50	80	1.9685	3.1496	-4.5	-5	5	10	-47	-47	0	-47	181	-29
80	120	3.1496	4.7244	-5	-6	7	14	-59	-59	0	-47	213	-34
120	150	4.7244	5.9055	-6	-7	8	16	-79	-79

OUTER RING TOLERANCE

ABEC 5 / ABEC 7
VALUES ARE IN .0001″

OUTER DIAMETER				OUTER DIAMETER TOLERANCE 0		RADIAL RUNOUT (MAX.)		WIDTH VARIATION (MAX.)		OUTSIDE CYLINDRICAL SURFACE RUNOUT WITH REFERENCE SIDE (MAX.)
MM OVER	MM INCL.	INCH OVER	INCH INCL.	ABEC 7P	ABEC 5P	ABEC 7P	ABEC 5P	ABEC 7P	ABEC 5P	ABEC 7P	ABEC 5P
0	18	0	0.7087	-2	-2	1.5	2	1	2	1.5	3
18	30	0.7087	1.1811	-2	-2	1.5	2	1	2	1.5	3
30	50	1.1811	1.9685	-2	-2	2	2	1	2	1.5	3
50	80	1.9685	3.1496	-2	-3	2	3	1	2	1.5	3
80	120	3.1496	4.7244	-3	-3	2	4	2	3	2	3
120	150	4.7244	5.9055	-4	-4	3	4	3	3	2	4

Too little or too much internal clearance will significantly influence factors such as heat, vibration, noise, and fatigue life.

In extreme applications that see high or low temperatures this clearance needs to be considered in the overall design to compensate for thermal expansion and contraction of housings and shafts.

SELECTING BEARING CLEARANCE (GENERAL GUIDELINES)

Operating Condition	Clearance
Clearance fit on both inner and outer ring. Low to no axial loading. No preload. Low speeds. Little tolerance for play. Low temperature.	C2
Low torque. Standard loads. Light preload. Slight interference fit on inner or outer ring, not both. Low to medium speeds. Average temperature.	CN
Very low torque. High loads. Heavy interference fits. High temperature. Preloaded.	C3,C4,C5

DEEP GROOVE BALL BEARING RADIAL INTERNAL CLEARANCE (UNITS: ΜM)

Nominal Bore Diameter (mm)		Clearance
Nominal Bore Diameter (mm)		C2		CN (NORMAL)		C3		C4		C5
over	Incl.	min	max	min	max	min	max	min	max	min	max
10	18	0	9	3	18	11	25	18	33	25	45
18	24	0	10	5	20	13	28	20	36	28	48
24	30	1	11	5	20	13	28	23	41	30	53
30	40	1	11	6	20	15	33	28	46	40	64
40	50	1	11	6	23	18	36	30	51	45	73
50	65	1	15	8	28	23	43	38	61	55	90
65	80	1	15	10	30	25	51	46	71	65	105
80	100	1	18	12	36	30	58	53	84	75	120
100	120	2	20	15	41	36	66	61	97	90	140
120	140	2	23	18	48	41	81	71	114	105	160
140	160	2	23	18	53	46	91	81	130	120	180
160	180	2	25	20	61	53	102	91	147	135	200
180	200	2	30	25	71	63	117	107	163	150	230
200	225	2	35	25	85	75	140	125	195	175	265
225	250	2	40	30	95	85	160	145	225	205	300
250	280	2	45	35	105	90	170	155	245	225	340
280	315	2	55	40	115	100	190	175	270	245	370
315	355	3	60	45	125	110	210	195	300	275	410
355	400	3	70	55	145	130	240	225	340	315	460
400	450	3	80	60	170	150	270	250	380	350	510
450	500	3	90	70	190	170	300	280	420	390	570
500	560	10	100	80	210	190	330	310	470	440	630
560	630	10	110	90	230	210	360	340	520	490	690
630	710	20	130	110	260	240	400	380	570	540	760
710	800	20	140	120	290	270	450	430	630	600	840

The retainer keeps the balls equally spaced providing equal load distribution and prevents unnecessary wear of the rolling elements.

Please contact us for further information.

PEEK and Vespel are generally considered vacuum compatible.

PPS offers the greatest chemical resistance and along with PEEK is FDA and USDA compliant.

PEEK and PPS offer the highest speed capability as a retainer material

Material compatibility in critical and or sensitive environments such as vacuum applications is subject to your bench testing and data sheet evaluation.

Since application environments vary greatly the following chart is simply a guideline.

RETAINER MATERIALS

Material	Max Temp	*Speed (dN)%**	Outgassing	Particle Generation	Cost
PEEK	480 F	650,000	Excellent	Excellent	Moderate
PPS	425 F	650,000	Good	Excellent	Moderate
VESPEL	500 F	600,000	Excellent	Excellent	High
TORLON	500 F	600,000	Excellent	Excellent	Moderate
TEFLON	550 F	30,000	Good	Good	Low
NYLON	250 F	250,000	Poor	Good	Low
PHENOLIC	300 F	600,000	Poor	Poor	Low

*d=inner bore diameter,N=RPM
%; Inner ring piloted, open configuration

RING AND BALL MATERIALS

CHROME STEEL

Chrome steel is one of a class of non stainless steels such as AISI 52100, En31, SUJ2, 100Cr6, 100C6, DIN 5401 which are used mostly in bearings

CERAMIC

Hybrid and full ceramic bearings are made using silicon nitride or zirconium oxide material.
Hybrid bearings are constructed of steel inner/outer rings, ceramic balls and retainers made of steel or thermoplastic.
Full ceramic bearings are 100% ceramic. Balls, rings and retainers.
The density of ceramic is 40% that of steel, the resulting reduction in weight reduces centrifugal forces imparted on the rings, reducing skidding, allowing up to 30% higher running speeds with less lubrication.
Silicon nitride balls have a 50 % higher modulus of elasticity (resistance to deformation) than steel, which increases rigidity and improving accuracy.
Ceramic balls have a smoother finish than steel, vibration and spindle deflection is reduced allowing higher speeds.
Ceramic has a lower coefficient of friction and is nearly twice as hard as bearing steel resulting in less wear with less lubrication. Bearing life can be increased.

440C STAINLESS STEEL

Applications may include some vacuum and clean processes or where general preventative corrosion resistance is desired. This material is magnetic.

300 SERIES STAINLESS STEEL (316 & 304)

PLASTICS

CERAMIC MATERIAL PROPERTIES

Mechanical	SI/Metric	Si3N4	ZrO2
Density	gm/cc (lb/ft³)	3.29	6
Porosity	% (%)	0	0
Color	—	black	ivory
Flexural Strength	MPa (lb/in²x10³)	830	900
Elastic Modulus	GPa (lb/in²x10⁶)	310	200
Shear Modulus	GPa (lb/in²x10⁶)	—	—
Bulk Modulus	GPa (lb/in²x10⁶)	—	—
Poisson’s Ratio	—	0.27	—
Compressive Strength	MPa (lb/in²x10³)	—	—
Hardness	Kg/mm²	1580	1300
Fracture Toughness KIC	MPa•m^1/2	6.1	13
Maximum Use Temperature (no load)	°C (°F)	1000	1500

THERMAL

Thermal	SI/Metric	Si3N4	ZrO2
Thermal Conductivity	W/m•°K (BTU•in/ft²•hr•°F)	30	2
Coefficient of Thermal Expansion	10–6/°C (10^–6/°F)	3.3	10.3
Specific Heat	J/Kg•°K (Btu/lb•°F)	—	—

ELECTRICAL

Electrical	SI/Metric	Si3N4	ZrO2
Dielectric Strength	ac-kv/mm (volts/mil)	—	—
Dielectric Constant	—	—	—
Dissipation Factor	—	—	—
Loss Tangent	—	—	—
Volume Resistivity	ohm•cm	—	>10¹⁰

CERAMIC VS. STEEL VS. STAINLESS STEEL

Item	Ceramic, Si3N4	52100 Steel	440C
Density	.114 lb/in³	0.282lb/in³	0.275lb/in³
Service Temp	1300 F	300 F	350 F
CTE	1.56µin/in-°F	6.94µin/in-°F	5.67µin/in-°F
Hardness	~ 76 RC	62 RC	58 RC
Magnetism	No	Yes	YES
Conductivity	Non-conductive	Conductive	Conductive
Corrosion Resistance	Excellent	Poor	Fair

CORROSION RESISTANCE COMPARISON CHART

WATER

MATERIALS	316/304 Stainless Steel	440C Stainless Steel	52100 Chrome Steel
Stream	A	B	NC
Domestic Water	A	B	D
Sea Water	A	NC	D

FOOD

MATERIALS	316/304 Stainless Steel	440C Stainless Steel	52100 Chrome Steel
Food Products	A	B	NC
Fruit & Veg. Juices	A	B	NC
Dairy Products	A	C	NC

DILUTE ACIDS

MATERIALS	316/304 Stainless Steel	440C Stainless Steel	52100 Chrome Steel
HCL	—	NC	NC
H2SO4	B	NC	NC
HNO2	A	A	NC
Phosphoric	B	NC	NC

ACIDS

MATERIALS	316/304 Stainless Steel	440C Stainless Steel	52100 Chrome Steel
H2SO4	A	NC	NC
HNO2	NC	NC	NC
Phosphoric	A	NC	NC

MATERIALS	316/304 Stainless Steel	440C Stainless Steel	52100 Chrome Steel
Industrial Atmospheres	B	B	C
Salt Air	A	C	C
Ammonia	A	C	B
Alkaline Salts	B	B	C

A = excellent, B = good, C = fair, D = poor, NC = Not compatible

CHEMICAL COMPOSITION OF BEARING STEELS

Chrome Steel

Spec	C%	Si%	Mn%	P%	S%	Cr%	Mo%	Ni	N	Hard-ness
SAE52100 SUJ2	0.95-1.10	0.15-0.35	0.50max	0.025max	0.025max	1.30-1.60	–	–	–	60-64 HRC

Stainless Steel

Spec	C%	Si%	Mn%	P%	S%	Cr%	Mo%	Ni	N	Hard-ness
AISI440C SUS440C	0.95-1.20	1.00 max	1.00 max	0.04 max	0.03 max	16.0-18.0	0.75 max	–	–	58-62 HRC
AISI303 SUS303	0.15 max	1.0 max	2.00 max	0.2 max	0.15 min	18.0 – 20.0	0.6 max	9.0	0.1 max	83 HRB

To help retain bearing lubrication and prevent contamination from the environment a seal (contact) or shield (non-contact) can be employed.

Often no seal (Open) is required when the bearing will be housed and externally lubricated or when operated in a vacuum.

TYPES

TYPE/MATERIAL	TEMP	SPEED CAPABILTY	TORQUE	AVAILABILITY
METAL SHIELD	350 F	GOOD	LOW	COMMON
RUBBER (CONTACT)	220 F	LIMITED	HIGH	COMMON
RUBBER (NONCONTACT)	220 F	GOOD	LOW	COMMON
TEFLON	500 F	GOOD	MED	COMMON
VITON	500 F	GOOD	MED	LIMITED

Some applications require interference fits such as:

Heavy radial loading
Intense vibration
Lack of axial clamping

Radial internal clearance is reduced by approximately 80% of the interference fit.

Interference fits are usually applied to the rotating ring.

Loose fits may be suggested when:

Axial clamping is possible, such a snap rings, locking collars or adhesive
Ease of assembly
Axial movement is required for spring preload or thermal movements

Fits are often overlooked and is arguably the most common bearing handling mistake.
The table below is simply a guideline as there are many influencing factors to be considered such as.

Load, speeds and temperatures
Ease of assembly and disassembly
Rigidity and accuracy requirements
Machining tolerances

Therefore the appropriate fit may fall somewhere in between.

ROTATING RING			INNER RING	OUTER RING
APPLICATION	DESIRED FIT TYPE	FIT(inches)	USE SHAFT DIAMETER	USE HOUSING DIAMETER
Low speed, or spring preload.	Loose	.0001L to .0005L	d – .0003 d – .0005	D .0001 D .0003
Medium speed	Line to Line	.0002L to .0002T	d – .0000 d – .0002	D – .0000 D – .0002
High speed	Light press	.0000 to .0004T	d .0002 d – .0000	D – .0002 D – .0004
High speed, high load	Tight press	.0002T to .0006T	d – .0002 d – .0004	D – .0004 D – .0006

STATIONARY RING			INNER RING	OUTER RING
Most applications	Line to line to loose	.0000 to .0004L	d – .0002 d – .0004	D – .0000 D .0002

L = Loose fit, T = Tight fit, d = Bearing I.D., D = Bearing O.D.

INNER RING TOLERANCE

ABEC 1 / ABEC 3
VALUES ARE IN .0001″

BORE DIAMETER				BORE TOLERANCE 0		RADIAL RUNOUT		WIDTH TOLERANCES 0
MM		INCH		ABEC 3	ABEC 1	ABEC 3	ABEC 1	ABEC 3	ABEC 1
OVER	INCL.	OVER	INCL.	ABEC 3	ABEC 1	ABEC 3	ABEC 1	ABEC 3	ABEC 1
0.6	2.5	.0236	.0984	-3	-3	2	4	-16	-16
2.5	10	.0984	.3937	-3	-3	2.5	4	-47	-47
10	18	0.3937	0.7087	-3	-3	3	4	-47	-47
18	30	0.7087	1.1811	-3	-4	3	5	-47	-47
30	50	1.1811	1.9685	-4	-4.5	4	6	-47	-47
50	80	1.9685	3.1496	-4.5	-6	4	8	-59	-59
80	120	3.1496	4.7244	-6	-8	5	10	-79	-79

INNER RING TOLERANCE

ABEC 5 / ABEC 7
VALUES ARE IN .0001″

BORE DIAMETER				BORE TOLERANCE 0		RADIAL RUNOUT (MAX.)		WIDTH VARIATION (MAX.)		REFERENCE RUNOUT WITH BORE (MAX.)
MM OVER	MM INCL.	INCH OVER	INCH INCL.	ABEC 7P	ABEC 5P	ABEC 7P	ABEC 5P	ABEC 7P	ABEC 5P	ABEC 7P	ABEC 5P
0	10	0	0.3937	-1.5	-2	1	1.5	1	2	1	3
10	18	0.3937	0.7087	-1.5	-2	1	1.5	1	2	1	3
18	30	0.7087	1.1811	-1.5	-2	1.5	1.5	1	2	1.5	3
30	50	1.1811	1.9685	-2	-2	1.5	2	1	2	1.5	3
50	80	1.9865	3.1496	-2	-3	1.5	2	1.5	2	2	3
80	120	3.1496	4.7244	-2.5	-3	2	2.5	1.5	3	2	3

OUTER RING TOLERANCE

ABEC 1 / ABEC 3
VALUES ARE IN .0001″

OUTER DIAMETER				OUTER DIAMETER TOLERANCE LIMIT 0		RADIAL RUNOUT		WIDTH TOLERANCES 0		FLANGE WIDTH TOLERANCE LIMITS 0		FLANGE DIAMETER TOLERANCE LIMITS 50
MM		INCH		ABEC 3	ABEC 1	ABEC 3	ABEC 1	ABEC 3	ABEC 1	ABEC 3	ABEC 1	ABEC 3	ABEC 1
OVER	INCL.	OVER	INCL.	ABEC 3	ABEC 1	ABEC 3	ABEC 1	ABEC 3	ABEC 1	ABEC 3	ABEC 1	ABEC 3	ABEC 1
0	18	0	0.7087	-3	-3	3	6	-47	-47	0	-47(2)	106(1)	-17(1)
18	30	0.7087	1.1811	-3	-3.5	4	6	-47	-47	0	-47	130	-20
30	50	1.1811	1.9685	-3.5	-4.5	4	8	-47	-47	0	-47	154	-24
50	80	1.9685	3.1496	-4.5	-5	5	10	-47	-47	0	-47	181	-29
80	120	3.1496	4.7244	-5	-6	7	14	-59	-59	0	-47	213	-34
120	150	4.7244	5.9055	-6	-7	8	16	-79	-79

OUTER RING TOLERANCE

ABEC 5 / ABEC 7
VALUES ARE IN .0001″

OUTER DIAMETER				OUTER DIAMETER TOLERANCE 0		RADIAL RUNOUT (MAX.)		WIDTH VARIATION (MAX.)		OUTSIDE CYLINDRICAL SURFACE RUNOUT WITH REFERENCE SIDE (MAX.)
MM OVER	MM INCL.	INCH OVER	INCH INCL.	ABEC 7P	ABEC 5P	ABEC 7P	ABEC 5P	ABEC 7P	ABEC 5P	ABEC 7P	ABEC 5P
0	18	0	0.7087	-2	-2	1.5	2	1	2	1.5	3
18	30	0.7087	1.1811	-2	-2	1.5	2	1	2	1.5	3
30	50	1.1811	1.9685	-2	-2	2	2	1	2	1.5	3
50	80	1.9685	3.1496	-2	-3	2	3	1	2	1.5	3
80	120	3.1496	4.7244	-3	-3	2	4	2	3	2	3
120	150	4.7244	5.9055	-4	-4	3	4	3	3	2	4