Bearings Technical Informations
- Nov 30, 2018 -

Bearing Material (inner race, outer race, balls)

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Steel, stainless steel and some variation in ceramic are all common types of bearing materials.


Steel

Modern industrial bearings have been made in a hardened type of steel (chromium) for many years and are by far the most popular material type in all applications today. All of the major manufacturers use steel as the de facto standard offering. All elements of the bearing (inner races, outer races and balls) are ground to produce a very smooth running track that allows the balls to rotate freely. Standard steel bearings have a useful characteristic in that they respond well to micro damage, they simply bed in some more with running. The friction does increase but it does not prevent a seizure


Stainless Steel bearings

Stainless steel is used as a material when the bearing is likely to be attacked by substances or when the ultimate in cleanliness is required (food/medical industry). From a rolling perspective, they have more friction than standard chromium steel bearings. Stainless steel bearings have an unwanted habit of going through a failure mechanism called galling, this is where the material micro delaminates and causes pitting, this generates more heat and eventually causes a seizure. On a bike, this is not a recommended material as the ingress of dirt can cause premature galling. They also have higher rolling friction coefficient.


Ceramic Bearings

Fully ceramic and hybrid ceramics have been popularized by companies like Enduro and Ceramicspeed. These bearings give good initial low friction but have an extremely poor life. They are really only fast for 500-600km. Check out the bearing performance chart. The material characteristics mean that these bearings are inherently brittle. Despite claims that the balls are rounder and therefore faster, the fact is the standard bearings are plenty round enough and do not destroy themselves. Ceramic bearings are extremely expensive.


Bearing cage material

The bearing cage is a guide piece that holds the balls in that separates the inner and outer races. It has light contact with the balls. Bearing cages in small bearings are generally made in two types. Either a pressed metal cage or an injection moulded plastic cage. At the time of writing SKF and Koyo were using injection moulded cages whilst INA, NTN, NSK, Nachi were using metal cages. From a performance perspective, the plastic cages make the bearings slightly lighter but compromise with a reduced life.


Bearing Seals

SpecificationNTNSKFFAGKoyoTimkenNSKEnduro
Two Seals Non ContactLLB2RZ2BRS--VVLLB
Two Seals ContactLLU2RS2RSR2RSPPDDULLU
One Seal ContactLURSRSRRSPPDU-
Two ShieldZZ2Z2ZR2ZDDZZ-
One ShieldZZZZRZDDZZ-
Snap RingNRNRNRNRGNR-
Steel CageBlankBlankJBlankBlankBlank-
Polyamide CageT2TN9TNH or TVHTN9PRBT1X-
Brass CageL1MYMMBRM-
Heat StabilizedPrefix TS3S1S1S1-X28-
Tight ClearanceC2C2C2C2HC2-
Normal ClearanceBlankBlankBlankBlankRBlank-
Greater than Normal ClearanceC3C3C3C3PC3-
Greater Than C3 ClearanceC4C4C4C4JC4-
Radial Clearance in MicronsRLXX-RLXX-CGXX--


If you need any bearings,just feel free to contact us.

Skypehannagreenpower
Wechat0086-137 7145 6936
WhatsApp0086-137 7145 6936
E-mailhanna@zkbearings.com
Hotmailhannabearing@hotmail.com


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