Bearing Cage Materials

7/25/2019 Bearing Cage Materials

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earing Cage Materials

Presented by : Aditya Gupta

MT-Mechanical

Under Guidance of

Mr. Manish Pandey Mr. Manish Singh

Mechanical Maintenance (Rotary)


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Acknowledgment

I am thankful to Mr. Manish Pandey Sir for giving me anopportunity to work on this topic while my stay at RotaryDepartment.

I am also thankful to all the people of Rotary from Mr.Manish Singh, Mr. Prabal Gupta, Mr. Ram, Mr. ManojGupta, Mr. Subish, Mr. Jayant, Mr. Subish and Mr.Shamroj Khan for giving me time out of their busy

schedule.


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WHAT IS BEARING

A bearing is a machine element that constrains relativemotion and reduces friction between moving parts to onlythe desired motion. The design of the bearing may, forexample, provide for free linear movement of the movingpart or for free rotation around a fixed axis; or, it may

preventa motion by controlling the vectors of normalforces that bear on the moving parts.

Bearings are classified broadly according to the type of

operation, the motions allowed, or to the directions of theloads (forces) applied to the parts.


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The term "bearing" is derived from the verb "tobear" a bearing being a machine element thatallows one part to bear (i.e., to support)another. (1)

Bearing is a mechanical element that permitsrelative motion between two parts, such as theshaft and the housing with minimum friction. (2)


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FUNCTIONS OF BEARING

The Bearing ensures free rotation of the shaft or the axlewith minimum friction.

The Bearing Supports the shaft or the axle and holds itin correct position.

The Bearing takes up the forces that act on the shaft orthe axle and transmits them to frame or the foundation.


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BEARING CAGE

In applications involving rolling element bearings,proper attention to cage design and materialsselection is essential in order to ensure reliable, long-term bearing performance. 3

With the exception of full complement bearings, allrolling bearings contain a cage. The number of cagesdepends on the number of ball or roller sets within the

bearing and on the cage design.


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The primary purposes of a cage are:

Keeping the rolling elements at a proper distance from each

other to reduce the frictional moment and frictional heat in thebearing.

Keeping the rolling elements evenly spaced to optimize loaddistribution and enable quiet and uniform operation.

Guiding the rolling elements in the unloaded zone, to improvethe rolling conditions and to prevent damaging slidingmovements.

In separable bearings, the cage is designed to retain the ballsin the outer ring so the rings can be handled separately. 4


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FACTORS IN CAGE SELECTION

Cost will always be a factor but following are important fromEngineering Point of View

Low coefficient of friction with ball and race materials

Compatible expansion rate with ball/ring materials

Low tendency to gall or wear

The ability to absorb lubricant

Dimensional and thermal stability

Suitable density

Adequate tensile strength

Creep resistance

High temperature

Corrosive atmospheres


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Classification of cages


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Cages can be classified according to themanufacturing process and material group into:

stamped metal cages

machined metal cages

polymer cages


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Stamped metal cages

Stamped metal cages are generally made of sheet

steel and with some exceptions, of sheet brass.

Depending on the bearing type, the following stampedmetal cages are available:

(a)ribbon-type cage

(b)riveted cage

(c)snap-type cage

(d)window-type cage


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a ribbon-type cage (a) a riveted cage (b) a snap-type cage (c) a window-type cage (d)

Stamped metal cages are lightweight. They provide ample space inside thebearing to maximize the effects of the lubricant.


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Machined metal cages

Machined metal cages are made of brass, steel or light

alloy.

Depending on the bearing type, design and size, thefollowing machined metal cages are available:

(a)two-piece machined riveted metal cage

(b)two-piece machined metal cage with integral rivets

(c)one-piece machined window-type metal cage

(d)double prong-type machined metal cage


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Machined metal cages generally permit higherspeeds, are typically used when forces, otherthan pure rotational forces, are superimposed

on the cage.


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a) two-piece machined riveted metal cage

b) two-piece machined metal cage with integral rivets

c) one-piece machined window-type metal cage

d) double prong-type machined metal cage


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Polymer cages

Polymer cages are injection moulded. Fabricreinforced phenolic resin cage are also there, but onlyfor super-precision bearings.

Depending on the bearing type, design and size, thefollowing polymer cages are available:

(a) polymer window-type cage

(b) polymer snap-type cage


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Good Combination of strength and elasticity

Good sliding properties on lubricated steel surfaces

Smoothness with the rolling elements resulting in less

frictional heat and wear in the bearing are

minimized.

Low density means that the inertial forces generated

are minimum.

Excellent running properties under poor lubricationconditions permit continued operation of the

bearing for some time without the risk of seizure and

secondary damage.


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(a)polymer window-type cage

(b)polymer snap-type cage


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Cage guidance

Stamped metal cages are typically guided bythe rolling elements.

Depending on the bearing type and design,machined metal and polymer cages areradially centred either on:

(a) rolling elements

(b) inner ring (shoulder(s))

(c) the outer ring (shoulder(s))


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Cages guided by the rolling elements permit thelubricant to enter the bearing easily.

Ring guided cages provide more precise guidance,

are typically used when bearing arrangements must

accommodate high speeds, frequent, rapid

accelerations or high vibration levels.


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Cage materials

Stamped metal cages

Sheet steel cages

Stamped sheet steel cages : continuously hot-rolled low carbonsteel.

Properties : Lightweight cages, Relatively high strength. Surfacetreated to further reduce friction and wear. Used in Stainless steel

bearings

Sheet brass cages

Brass, Some small and medium-size bearings.Properties : In applications like refrigeration compressors that use

ammonia, season cracking in sheet brass might occur, thereforemachined brass or steel cages should be used instead.


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Stamped metal cages

Type Material Properties uses

Sheet Steel cages Hot Rolled LowCarbon steel

Light Weightcage

High StrengthStainless steel

bearings

Sheet Brass cages Brass Susceptible to

corrosion from

NH3and OtherLubricants

Small and

Medium Sizedbearings


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Machined steel cages

Non-alloyed structural S355GT (St 52) steel

Properties : To improve sliding and wear-resistance properties,some machined steel cages are surface treated. Not affected bythe mineral or synthetic oil based lubricants normally used for

rolling bearings, or by the organic solvents used to cleanbearings.

Used for large bearings or in applications where there is a dangerthat season cracking, caused by a chemical reaction, may occur

if a brass cage is used.

Operating temperatures :


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Machined brass cages

CW612N cast or wrought brass

They are unaffected by most common bearinglubricants, including synthetic oils and greases, andcan be cleaned using normal organic solvents.

Operating temperatures


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Type Material Properties Max Temp. Uses

MachinedSteel cages

Non AlloyedStructural

steel S355GT

Good wearingand slidingProperties

Not effected by

Lubricants

3000 C LargeBearings,harsh

aggressiveMedium

MachinedBrass

Cages

CW612N castor wrought

brass

Unaffected byLubricants

2500 C Small andMedium size

bearings


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Polymer cages

Polyamide 66

Injection moulded polyamide 66 (PA66) with or withoutglass fibres

Properties : Good combination of strength andelasticity. Mechanical properties are temperature andlubricant dependent.


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The permissible operating temperature is defined as the temperature that provides acage ageing life of at least 10 000 operating hours.


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Medias can be aggressive and mild. A typical example isammonia, used as a refrigerant in compressors. In those cases,cages made of glass fibre reinforced PA66 should not be used atoperating temperatures above 70 C (160 F).

Low temperature limit

Polyamide loses its elasticity, which can result in cage failuresunder extremely cold conditions. As a result, cages made of glassfibre reinforced

Operating Temperature >=40 C (40 F).

In applications where a high degree of toughness is a criticaloperational parameter, such as in railway axle boxes, a super-tough modified PA66 can be used.


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Polyamide 46

Glass fibre reinforced polyamide 46 (PA46) is the standard cage materialfor some small and medium-size CARB toroidal roller bearings.

Permissible operating temperature is 15 C (25 F) higher than for glassfibre reinforced PA66.

Polyetheretherketone

Glass fibre reinforced polyetheretherketone (PEEK)High speeds, chemical resistance or high temperatures.Properties : Superior combination of strength and flexibility, highoperating temperature range, high chemical and wear-resistanceTemperature


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Phenolic resin

Lightweight, fabric reinforced phenolic resin cages Withstand

heavy inertial forces, but are not able to accommodate highoperating temperatures.

Used as standard in super-precision angular contact ballbearings.

Polymer cages


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Polymer cages


Polyamide66

Injectionmoulded

PA66 w orw/o Glass

fibres

GoodCombination ofstrength andelasticity

Temp &

LubricantDependent

200oC150oC (HighSpeed use)

High speeds,chemicalresistance orhightemperatures.

Polyamide46

PA46 Greater TempResistant

15oC (+PA66Temp)

Small andMedium size

bearings


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Polyetheretherketone Glass fibrereinforcedPEEK

Superior

Combination ofstrength andelasticity

High Temp,chemical andwear resistance

Upper : 70o

C(foraggressive

media)Lowe : -40oC

Applications

of High degreeof toughnessas in railwayaxle boxes

Phenolicresin

Withstand HighInertail forcesbut not High

Temp.

super-precisionangular

contact ballbearings.


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Selection of bearing type

Bearing LoadBall Bearings Low and Medium

Roller Bearings Heavy

Bearing Shaft Diameter

Ball Bearings Low and Medium

Roller Bearings Large

Bearing Alignment

Self Aligning Ball & Roller Chances of Misalignment

Normal No


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Bearing Load Direction Visual

Deep Groove ball

Bearings Angular Contact

Bearings Spherical Roller

Bearings

Radial Combined

Radial andAxial

Thrust Ball Bearings Medium Axial

Cylindrical RollerBearings

Heavy Thrust


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Bearing Speed and Temperature

deep groove ball bearings angular contact bearings cylindrical roller bearings

High

Brass Bearings Low and Medium

Bearing Rigidity Control

Double Row Cylindrical Roller Taper Roller Bearings

High

Single Row bearings Normal


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Bearing Noise

Deep Groove Ball Bearings Low (Household)

Ball Bearings Medium

Cylindrical roller Bearings High


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References

Thanking them in anticipation

1- Wikipedia

2- Gary Hughes, Product Engineering Manager at The Barden Corporation

3- SKF Rolling bearing Manual

Mechanical Engineering Design 7thEd. Shigley

Design of Machine Elements by Bhandari

SCHAEFFLER Website

Thank you

Documents

Bearing Cage Materials