polylube design-guide copy

5/28/2018 POLYLUBE Design-guide Copy

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103 Industrial Park DrIVE / P.O. Box 176 / Walkerton, IN 46574 USA / 800.918.9261 / Ph: 574.586.3145 / Fx: 574.586.7336 / polygoncompOSITES.com

POLYLUBECOMPOSITE BEARINGS

& BUSHINGS

POLYMEDCOMPOSITE MEDICAL

TUBING

POLYSLIDECOMPOSITE CYLINDER

TUBING

POLYSTRUCTURECOMPOSITE SHAPES

& FORMS

POLYGON TUBEELECTRICAL GRADECOMPOSITE TUBING


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HIGHLIGHTS


2

POLYLUBE Design guideTABLE OF CONTENTSSELF LUBRICATED COMPOSITE BEARINGS

INTRODUCTION 3-9Polygons company history and product manufacturing divisions.

PRODUCT INFORMATION 10-29

POLYLUBE FIBER SERIES BEARINGS 10-12The ideal candidate for highly loaded bearing joints requiring low friction and low wear over 1.5 million cycles.

POLYLUBE MRP AND MRP-SL BEARINGS 13-14A superb bearing material for agriculture, construction and material handling applications requiring good

load capacity, low frictional values, and superior wear characteristics.

POLYLUBE GLASS TAPE BEARINGS 15-19An excellent solution for bearing applications where stick/slip is of concern.

POLYLUBE IFR BEARINGS 20-21A bearing with optimized structure for resistance to applications with repeated impact fatigue orstress/strain conditions.

POLYLUBE HIGH TEMPERATURE BEARINGS 22-23A bearing designed for environments over 450F or where thermal expansion stability is critical.

POLYLUBE GUIDE ROD BUSHINGS 24-29A guide rod bushing for pneumatic cylinder applications where corrosion, high misalignment or edgeloading, low friction and excellent wear characteristics are desired.

BEARING DESIGN PRINCIPLES 30-35

STANDARD SIZES 36-46

SUPPLEMENTARY DATA 47


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POLYLUBE Design guide

HIGHLIGHTS

INTRODUCTIONSELF LUBRICATED COMPOSITE BEARINGS


POLYGON COMPANYFounded in 1949 by a chemist work-

ing on advanced composite materials

during World War II at the U.S. Wright-

Patterson Air Force base, Polygon Com-

pany has grown into an engineered materials company

with multiple manufacturing facilities and global distribu-

tion and sales offices around the world. Polygons original

patents on composite self-lubricating bearings in the mid 1960s stand as a hallmark in the devel-

opment of journal bearing technology. Since that time, Polygons ongoing research and develop-

ment activities have resulted in multiple patents on innovative self-lubricating products as well as

proprietary manufacturing capabilities that allow Polygon to project superior value in the journal

bearing marketplace.

Corporate research and development activities, including an in-house

bearing test laboratory, are located in the companys corporate offices

and primary manufacturing location in Walkerton, Indiana (approxi-

mately 90 miles east of Chicago, Illinois).

POLYGONS CORPORATE STRUCTURE IS CENTERED AROUND

FIVE PRODUCT MANUFACTURING DIVISIONS: PolyLube self-lubricating composite bearings.

PolyMed (USP Class VI approved) medical composites for minimally invasive surgeries.

The Polygon Tube double insulation for hand-held power tools and electrical and distribution.

Electrical Distribution and Control composite insulation materials.

Continuous Fiber Thermoplastic (CFT) materials and pultruded products.

Polygons original

patents stand as a hall-

mark in the development o

bearing technology.


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HIGHLIGHTS


4

WHAT IS A COMPOSITE BEARING?Polygons line of PolyLube bearingsuses a fiberglass filament wound

structure which incorporates a propri-

etary epoxy resin matrix that results

in a very high strength bearing that is

naturally concentric with no seam or

overlap. This high strength laminate

construction allows for the use of a

thin wall (1/16" to 1/8") bearing

which reduces the size and weight of

the assembly. The resulting compos-

ite material exhibits a very low coeffi-

cient of friction coupled with highload-bearing capacity.

POLYLUBE LINER DESIGNPolyLube bearings utilize a proprietary design that ensures the anti-friction backing is locked into

the backing material with more than a simple adhesion effect. This proprietary design also drives

excellent resistance to impact fatigue and cavitation problems.

The PolyLube Fiber and MRP series bearings have their liners applied in a dry manufacturing

mode. They are inherently very resistant to impact because the liner backing has high strength

fiberglass filaments interwoven into the liner backing.

The differences in liner construction can be seen most dramatically during three periods: first,

how coefficient of friction and wear change during the break-in period, second, how the bearing

handles contamination in a dirty or unsealed environment, and third, long term bearing life. Differ-

ences in liner construction can also impact performance in the following areas:

Coefficient of FrictionThe required breakaway torque & startup forces required.

Impact FatigueHow the bearing handles shock or impact loading.

Amount of WearThe orientation of the PTFE in relation to the mating surface as well as the

content of the PTFE will impact the amount of wear the finished journal bearing will exhibit.

Time for Achieving Sufficient PTFE Film TransferThe liner construction will impact the length oftime as well as the operating conditions required to have the PTFE film properly transfer from

the inner diameter of the bearing to the outer diameter of the mating surface.

This high strength

laminate construction

allows for the use of a

thin wall bearing.

POLYLUBE Design guideINTRODUCTIONSELF LUBRICATED COMPOSITE BEARINGS

PolyLube Fiber Series Wear Surface

PolyLube MRP Wear Surface


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HIGHLIGHTS



GO GREASELESS!PolyLube bearings not only exhibit excellent load capacities, low frictional valuesand resistance to corrosion, they also allow for true self-lubrication. As a result, all

secondary lubrication systems and design guidelines that are related to lubricants

can be eliminated from industrial applications.

WHAT ARE THE DESIRED CHARACTERISTICS OFJOURNAL/PLANE BEARING MATERIALS?In general, journal/plane bearing materials should have the following characteristics

in order for the bearing assembly to be properly designed:

The PTFE super-filament

used in the bearing wear

surface exhibit tensile

strengths 20-times greate

than traditional PTFE

resins.

10,000

20,000

30,000

40,000

CastBronze

PorousBronze

AlloyedBronze

Steel-BackedBronze

HardenedSteel

ZincAluminum

Fabric-ReinforcedPhenolic

ReinforcedTeflon

POLYLUBE

REQUIRESLUBRICATION

SELFLUBRICATING

MAX.

DYNAMICCAPACITY-PSI

(LESSTHAN5SFPM)

MATERIAL

WITH

NOLUBRICATION

ONLY

WHENLUBRICATED

GREASED VERSUS GREASELESS JOURNAL BEARING COMPARISONS

0 2 4 6 8 10 30 40 50

0

20

40 BEARING PRESSURE (psi 1,000s)

Molded Nylonsand Acetals

Single or Multi-Lubricated FilledMolded Composites

Sintered Iron-Bronze

Metal Backed, Plastic LinedGreased Bearings

30% Reinforced Thermoplastics

Metal Backed

KEY

2 fpm

Filled PTFEsand Unfilled Polyethylenes

PolyLubePTFE Fiber SeriesBearing

PolyLube Bronze Tape Liner

ENGINEEREDWEARSURFACES

MATERIALFAMILYCOMPARISONS

0 2 4 6 8 10 30 40 50 60

0

20

40 BEARING PRESSURE (psi 1,000s)

ENGINEEREDWEARSURFACES

MATERIALFAMILYCOMPARISONS

Filled PTFEsand Unfilled Polyethylenes

Molded Nylonsand Acetals

Single or Multi-Lubricated FilledMolded Composites

Sintered Iron-Bronze

Metal Backed, PlasticLinedGreased Bearings

30% Reinforced Thermoplastics

Metal Backed

PolyLubePTFE BronzeTape Liner

PolyLubeFiberSeriesBearing

JOURNAL BEARING STATIC LOAD COMPARISONS JOURNAL BEARING DYNAMIC LOAD COMPARISONS

1. TRULY SELF-LUBRICATING. Many materials

claim to offer some level of self-lubrication;

however, many (especially sintered metal

structures) lose their self-lubrication proper-

ties quickly during operation. When the lubri-

cation fails, metal-on-metal contact results.

Premature bearing failure generally quickly

follows.

2. EMBEDDABILITY. A properly designed com-

posite journal bearing should have the ability for

the bearing liner to absorb or embed within it-

self wear debris or airborne dirt particles.

3. PV RATING. The PV rating should be easy to

understand, and fit most application environ-

ments with a good match between the bear-

ing pressure and surface velocity

capabilities.

4. QUICK TRANSFER OF PTFE FILM TO SHAFT.

The key to self-lubricating bearings is the rapid

transfer of PTFE from the bearing ID to the shaft

surface during the initial break-in phase. The film

of PTFE on the shaft functions as a dry lubricant,

which reduces the friction and wear rate.

5. FIBER ORIENTATION TO MINIMIZE FRICTION.

In a properly designed self-lubricating bearing,

the bearing will exhibit a low coefficient of fric-

tion when the contact surface is on the ends of

the PTFE fibers.

6. HIGH PERCENT OF PTFE NEAR THE SURFACE.

It is not sufficient to simply have PTFE fibers

on the wear surface. A high percent of PTFE is

desirable near the surface of the bearing to

provide an ample amount of dry lubricant for

wear and friction reduction.


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HIGHLIGHTS


6

Many materials claim to

offer some level of self-

lubrication; however, many

lose their self-lubrication

properties quickly during

operation.


WHAT COMPOSITES PROFESSIONALS MEANS TO YOU!Unlike any other company in the journal bearing market, Polygon is the only organization withcomposite self-lubricating bearings as a primary product focus. Other bearing organizations see

this product line as a necessary offering to satisfy the design needs of the OEM market.

FOR POLYGON, THIS FAMILY OF MATERIALS IS OUR CORE COMPETENCY, IT IS WHAT WE DO, IT IS

WHAT WE ARE PROFESSIONALS AT. Polygon can better predict the performance of this type of

bearing, can better define what factors drive product performance, and has a stronger manufac-

turing infrastructure to support your business needs. Our abilities as an organization to specify

sizing, assembly, and design parameters are unmatched in the self-lubricating composite bear-

ing industry. Why? Because it is what we do. The value to you? Polygon Company has the best

designed, highest performing bearing material available, at the best cost in the industry.

THE TRUE VALUE OF SELF-LUBRICATIONTodays design engineering community must continually search out materials that allow for an

increase in performance capabilities in conjunction with total, system based cost savings. The

question still remains: What is the true value of self-lubrication?

Experienced OEM design engineers know that one of the most common failures for bearing de-

signs is when lubrication is not properly maintained. Conceptually, a bearing design that is prop-

erly sealed and lubricated should result in trouble-free field service. Unfortunately, this is not the

case in most applications. In todays environments it is fairly common that greased joints are not

maintained properly. As a result, the boundary/mixed lubrication condition diminishes and thebearing life is limited.

AssemblyCost

2

0

4

6

8

Co

stFactor

Greased Bearing Self-Lubricating Composite Bearing

HousingFabrication

Cost

ZerkAssembly

Cost

FactoryGreasing

UnitPurchase

Price

OngoingMaintenance

Cost

TotalCost of

Ownership

TOTAL COST OF OWNERSHIP ANALYSIS

Self-lubricating bearings eliminate secondarypin and housing fabrication required forgreased bearings.

The environmental issues around grease are

only now coming to light. With self-lubrica-tion all environmental contaminants areeliminated.


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HIGHLIGHTS



THE TRUE VALUE OF SELF-LUBRICATION (CONTINUED)In addition to the potential of failure if bearings are not properly lubricated, the total cost of owner-ship for a bearing that must be lubricated is greater than the total cost of a self-lubricating com-

posite bearing. Most OEMs clients have found that the cost of purchasing, assembling, and

maintaining a greased bearing joint is at a minimum 1.5 times to a maximum of 4 times the cost

of a self-lubricating bearing joint. Equipment rental yards are becoming increasingly sensitive to

the liability associated with greased bearings.

At the most simple level, external lubrication introduces an uncontrollable design variable for

todays OEM engineers. Once the finished product is shipped to the customer, the customer must

properly maintain the bearing assembly or deal with the potential for failure, and whatever liability

or warranty claims may come from that. If proper maintenance is a concern, the best solution is a

self-lubricating composite bearing. Self-lubrication is the ideal solution since it fully lubricates the

contact surfaces, does not attract dust or dirt (as both grease and oil will), results in no environ-mental problems as grease or oil can, and requires absolutely no field or long term maintenance.

WHEN TO USE POLYLUBE BEARINGS When self-lubrication is required.

When bearing neglect could lead to product liability claims or premature failure.

When conventional lubricants will not function or cannot be used (as in the food processing and

pharmaceutical industries).

When bearing, lubrication system, and maintenance costs need to be closely monitored.

When wide temperature ranges, particularly at low temperatures, require bearing performance

stability.

When stick-slip conditions exist.

When high load capacities are needed.

When resistance to chemical, galvanic, or fretting related corrosion is a problem.

When weight reduction is desired.

When galling and scoring need to be minimized.

When shock loads present a problem.

When electrical insulation is required.

COMPOSITE BEARINGS ARE SIMPLY BETTERIt is a design reality that todays OEM engineering community has many bearing alternatives tochoose from. When making a design decision, it can be difficult to weigh through performance dif-

ferences between materials, and come to a conclusion that optimizes your design. In the following

pages, a basic application-driven discussion is presented between composite bearings and tradi-

tional metallic or thermoplastic bearings.

Hex ID and special ID shapes can be incorpo-

rated into the bearing as well.

Polygons CNC fabrication equipment allows fospecial designs to be economically incorporat

One of the most common

failures for bearing design

is when lubrication is not

properly maintained.

PolyLube bearings elimina

lubrication maintenance.


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HIGHLIGHTS

GREASED BEARINGSThe most obvious difference? This family of bearing materials requires perpetual greasing. When

the lubricating film fails due to contamination, the bearing will prematurely wear. Performance of

this bearing is entirely reliant on the end user properly maintaining and servicing the bearing

joint in question.

ADDITIONAL PERFORMANCE DIFFERENCES:

Loads only to 20,000 PSI with lubrication compared to PolyLube dynamic loads to 30,000 PSI

and static loads of 60,000 PSI without lubrication.

Greased metal-backed bearing materials have very fine operating temperature ranges. They

traditionally span from -40 to +210F compared to PolyLube ranges from 325F. Once mixed-mode lubrication (grease &/or oil) fail due to particulate ingestion and contamination,

this type of bearing can no longer operate successfully.

SINTERED METALLIC BEARINGSSintered metallic bearings have innate limitations due to their structure and to the mechanisms

by which they achieve lubrication. The structure of a sintered material bearing dramatically re-

duces impact or shock loading capability as well as limits both the static and dynamic loading ca-

pacities when compared to PolyLube bearing materials.


At best, dynamic capacities of 8,000 PSI.

Alloyed bronze bearings have the highest dynamic capacity within

this family-and that is 10,000 PSI or less than 5 SFM with lubrication.

Lowered impact or fatigue strength properties.

Prone to corrosion and shaft fretting.

Many times burnishing tools are required to get product to final geometric tolerances.


8


Performance of a greased

bearing is entirely reliant

on the end user properly

maintaining and servicing

the bearing joint

Cast Bronze 6,000* 160* 10 8.8

Porous Bronze 4,000** 160** 10 7.5

Alloyed Bronze 10,000* 200* 16 8.1

Steel-Backed Bronze 3,500* 200* 8 8.0

Hardened Steel 40,000* 200* 7 7.9

Zinc Aluminum 5,500* 200* 15 5.0

Fabric-Reinforced Phenolic 6,000* 200* 20 1.6

Reinforced Teflon 2,000 500 55 2.0

POLYLUBE Fiber Series 30,000 325 7 1.87

*with lubrication **oil impregnated DuPont

When grease fails these bearings quicklywear through and produce intimate contactbetween the shaft and bearing.

MATERIAL MAX. DYNAMIC MAXIMUM THERMAL SPECIFICCAPACITY-PSI TEMPERATURE EXPANSION GRAVITY

(LESS THAN 5 SFPM) F 10-6 IN./IN./F

Sintered structure bearings cant handle theload of composite bearings.

Filled thermoplastics have no chancein highly loaded environments.


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HIGHLIGHTS



FILLED THERMOPLASTIC BEARING MATERIALS Sizing predictability. Due to the fact that these bearings are manufactured via injection molding,

sizing can be difficult to predict.

Impact Fatigue. Even glass filled thermoplastic resins can only go

so far with resistance to repeated impact.

Limited Self-Lubrication Capabilities. Lubrication for filled thermoplastics

does not utilize as significant a percentage nor as effective a type of PTFE

as do PolyLube bearing materials. As a result, the in-use coefficient of

friction and break-in characteristics of each bearing material is different.

METAL BACKED BEARINGSMetal backed bearing materials have been an obvious choice for design engineers given their fea-ture/benefit combination in association with product price. With recent developments in manu-

facturing techniques, Polygons line of PolyLube bearings are attaining market penetration

against this family of conventional bearing materials.


With any metal backed bearing, once the overlay is broken into the shaft is in intimate contact

with the metal backingthis can result in premature failure.

Dynamic capacities of this family of bearings is typically at a maximum of 20,000 PSI

compared to 30,000 PSI with a PolyLube Fiber Series bearing.

As with any metal structure, this type of bearing is subject to severe corrosionan issue that

can occur as quickly as 24 hours into basic immersion testing.

ROLLING ELEMENT BEARINGSPolyLube bearings are able to handle higher load capacities, and in particular shock loading,

than traditional rolling element bearings.


Reduce the weight and profile of the bearingin many cases the weight and profile of the bearing

can be reduced by over 50%.

The PolyLube bearing family exhibits much higher static load capacities than traditional rolling

element bearingsan equivalent sized needle bearing will only have 30% of the static capacityof a composite PolyLube bearing.

No external lubrication is required with the PolyLube bearingthere are no concerns with failed

lubrication media resulting in shaft damage.

By using the PTFE film transfer process instead of macro mechanical moving parts, the PolyLube

family of bearing materials is able to have more predictable performance stability over the

life of the application.

Thermoplastics are highly sub-ject to cold flow under load-ingsomething PolyLubebearings do not struggle with.

Metal backed bearings ar

subject to severe corro-

sionan issue that can

occur as quickly as 24

hours into basic immersion

testing

Once the overlay is worn through, intimate

contact and failure can quickly result.


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HIGHLIGHTS

FIBER SERIES BEARINGSSELF LUBRICATED COMPOSITE BEARINGS

Product DescriptionThe PolyLube Fiber Series bearing is a high load,low RPM bearing designed for rigorous industrial

equipment applications. The bearing is manufac-

tured by a filament winding process that results in a

continuous fiberglass filament backing composition-

ensuring excellent mechanical properties (especially

fatigue resistance). The filament wound fiberglass

structure uses a high strength, corrosion resistant

epoxy resin as the matrix material. The high strength

backing permits the use of a thin wall (1/16" to 1/8")

bearing which can often reduce the size and weight of

the finished bearing assembly. PolyLube Fiber Series

bearings will support a bearing load of 30,000 PSI,while handling high radial and axial stresses. They re-

sist high shock loading and impact fatigue due to their

unique high strength continuous fiberglass backing.

These qualities make PolyLube bearings ideal for high

load operation in rotational and linear movements as

well as in oscillation. This family of materials exhibits

exceptional dimensional stability and performance

predictability over wide temperature ranges (325F).

Product SchematicThe high strength composite fiberglass backing permits optimal strength and rigidity, with a modulusof elasticity of approximately 6 x 106 PSI. This property allows the PolyLubebearing to be rigid enough

to support heavy loads and pliant enough to tolerate moderate shaft

misalignments without over-stressing the bearing edges.

The bearing surface is composed of a uniquely designed woven struc-

ture of PTFE super-filaments, which exhibit tensile strengths twenty

times greater than PTFE resins. As a result, the bearing is not subject to

cold flow under high loading conditions. These PTFE super-filaments

are also the primary mechanism for allowing the PolyLube product to

operate in a true self-lubricating mode. No secondary lubrication is

necessary, even during start-up conditions, due to the film transferself-lubrication process.

As the bearing joint begins service, the PTFE undergoes a phase

change and smears around the mating pin surface. As the PTFE film

develops, it transfers from the inner diameter to the outer diameter of

the pin, smoothing out any macroscopic surface imperfections and al-

lowing the bearing to have a very low coefficient of friction and mini-

mal long term wear, even under high loading conditions.


10

PTFE WITH WEARRESISTANT MATERIAL

WEAVE

HIGH STRENGTHCOMPOSITE FIBERGLASS

EPOXY BACKING

WEAR RESISTANT DEBRISLAYS IN VOIDS

EXPOSED PTFEREDUCES FRICTION

RADIAL LOADING PRESSURE (PSI x 103)

COEFFICIENT OF FRICTION FOR A POLYLUBE FIBER BEARING

COEFFICIEN

TOFFRICTION

0.025

0.050

0.075

0.100

0.125

0.150

0.175

0.200

0.225

0.250

0.275

2 4 6 8 10 1 2 1 4 1 6 1 8 2 0 2 20

PolyLube

Fiber SeriesBearings are the ideal

candidate bearing material

for highly loaded bearing

joints requiring long term,

trouble free maintenance.

FIBER SERIESBEARINGS


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HIGHLIGHTS


In some conditions, as much as

0.001" of wear may occur during the

break-in period, while in other opera-

tions, break-in wear may be negligi-

ble. The elapsed time for break-in is

PV (Pressure and Velocity) depend-

ent. The equilibrium wear rate varies

from operation to operation, due to a

number of factors including: loads,

speeds, shaft hardness, material, and

shaft surface finish. For more specific

guidance on the break-in period to

anticipate given your specific applica-

tion, please contact a PolyLube appli-cation engineer.

Following the break-in period, the wear rate stabilizes, remaining relatively constant for the bearings

life. Testing of the Fiber Series Bearing at 22,500 pounds, with 50 oscillation angle, resulted in stable

wear under 0.005" at over 1.5 million cycles.

PolyLube Fiber Series bearings are designed to minimize wear; however, the bearing wear is ef-

fected by the general operating conditions, such as speed, sliding distance and load. With inter-

mittent rotation or oscillation, radial wear should be negligible over thousands of hours. Hard

chrome plating gives excellent wear performance and protects the shaft from corrosion. Coatings

such as chrome, electroless nickel, or nitro carbonizing are all common treatments for shaft ma-

terials used with PolyLube bearings.


PolyLube Fiber Series

bearings will support

a dynamic bearing load

of 30,000 PSI

PTFE Film Transfer Process

Before Film Transfer Process

After Film Transfer Process

PTFE Film

The above schematic represents a detailedperspective on how the surface condition othe mating pin changes both before and aftthe PTFE film transfer process.

FIBERGLASS BACKING

PTFE WEAVE

PTFE WEAVE

FIBERGLASS BACKING BREAK-INMATERIAL

TOP OFRESIN

FLAKES

TOP OFWEAVE

NEW

BEARING

STABILIZEDBEARING

As the bearing begins to cycle, the initial coefficient of friction will increase inrelationship to the longer term, broken-in frictional values. This is due to the

fact that a small layer of resin, generated by the manufacturing process of thecomposite backing, is being slowly worn away.


13/48


HIGHLIGHTS



With intermittent

rotation, radial wear

should be negligible over

thousands of hours.

MECHANICAL AND PHYSICAL PROPERTIESThe PolyLube Fiber Series bearing can withstand static loads of approximately 60,000 PSI and30,000 PSI under dynamic loading. At these loading levels, minimum distortion will occur. For

dry running applications, the maximum speed is approximately 10 surface feet per minute.

This bearings operating temperature range is 325F. Maximum continuous operational surface

temperature for the standard formulation is 325F, depending upon load characteristics. The bear-

ing has been heat stabilized at these temperatures, so that little dimensional change will occur in

the bearing during operation. In a free state, the coefficient of expansion of the PolyLube Fiber Se-

ries bearing is approximately 7 x 10-6 in/in/F, similar to the coefficient of expansion for steel, and

actually less than some metals.

APPLICATIONSPolyLube Fiber Series bearings are the bearing of choice in

highly loaded bearing joints where a life cycle of over

500,000 cycles is desired. Testing has shown this bearing

has wear under 0.006" after 1.6 million cycles. Applications

include material handling equipment, high duty cranes,

earth-moving equipment, construction equipment, agricul-

ture equipment and food processing systems.

Ultimate Compression Strength (PSI) 60,000

Unit Load Limit (PSI) 30,000

Temperature Range (Standard Formulation)* 325F

Coefficient Of Thermal Expansion (in/in/F) 7 x 10-6

Thermal Conductivity (BTU in/(hr Ft2 F)) 1.8-2.3

Water Absorption (2 Hours) 0.12%


Specific Gravity 1.87

Maximum Velocity (SFM) 10

*Note: Special resin formu lation available up to 500F.

FIBER SERIESBEARINGS

12


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HIGHLIGHTS

MRP AND MRP SL BEARINGSELF LUBRICATED COMPOSITE BEARINGS


These issues come togethe

to allow Polygon to sell

a product better matched

customers needs.

PRODUCT HISTORYFrom a pure load carrying and performance perspective PolygonsFiber, MRP and MRP-SL series bushings are practically identical. Our

desire has not to only be the industry leader in performance, but in

cost as well. A through analysis and value stream mapping of the

manufacturing process resulted in the development of the MRP and

MRP-SL product. Essentially a bushing family of equal performance,

but at a lower price point.

PRODUCT DESCRIPTIONThe MRP and MRP-SL are identical in liner architecture components

and construction. The MRP-SL has one unique and added lubricant em-

bedded within the surface of the liner material to decrease the initialcoefficient of friction. This small change was initiated because in cer-

tain lightly loaded joints, upon initial actuation, an intermittent stick-

slip or noise could be generated. The MRP-SL addresses this issue by

decreasing friction and reducing the typical break in period.

PIN SURFACE FINISH

CALCULATED INITIAL COF FOR POLYLUBE MRP BUSHINGS4140 Nitrided Shafts

COEFFICIENTOFFRICTION

0.00

0.05

0.10

0.15

0.20

0.25

MRP 13 Ra MRP 13 Ra MRP 65 Ra MRP-SL 65 Ra MRP-SL 13 Ra

0.30

0.35

MRP-SL 13 Ra

STATIC COF

DYNAMIC COF


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HIGHLIGHTS

MRP AND MRP SL BEARINGSELF LUBRICATED COMPOSITE BEARINGS


14

With intermittent

rotation, radial wear

should be negligible over

thousands of hours.

PRODUCT DESCRIPTION (CONTINUED)PolyLube MRP bearings are designed to minimize wear; however, the bearing wear is effected by thegeneral operating conditions, such as speed, sliding distance and load. With intermittent rotation or

oscillation, radial wear should be negligible over thousands of hours. Hard chrome plating gives ex-

cellent wear performance and protects the shaft from corrosion. Softer coatings such as cadmium

or zinc may wear off more quickly and may not stand up to the desired service requirements.

MECHANICAL AND PHYSICAL PROPERTIESThe PolyLube MRP bearing can withstand static loads of approximately 60,000 PSI and 30,000

PSI under dynamic loading. At these loading levels, minimum distortion will occur. For dry running

applications, the maximum speed is approximately 10 surface feet per minute.

This bearings operating temperature range is 325F. Maximum continuous operational surfacetemperature for the standard formulation is 325F, depending upon load characteristics. The bear-


the bearing during operation. In a free state, the coefficient of expansion of the PolyLube MRP

bearing is approximately 7 x 10-6 in/in/F, similar to the coefficient of expansion for steel, and ac-

tually less than some metals.

APPLICATIONSPolyLube MRP bearings are the bearing of choice in highly

loaded bearing joints where a life cycle of over 500,000 cycles

is desired. Testing has shown this bearing has wear under

0.006" after 1.6 million cycles. Applications include material

handling equipment, high duty cranes, earth-moving equip-

ment, construction equipment, agriculture equipment and food

processing systems.



Temperature Range (Standard Formulation)* 325F


Thermal Conductivity (BTU in/(hr Ft2 F)) 1.8-2.3Water Absorption (2 Hours) 0.12%




*Note: Special resin formulation available up to 500F.


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HIGHLIGHTS

GLASS TAPE BEARINGSELF LUBRICATED COMPOSITE BEARINGS


The Glass Tape bearing

has a lower coefficient of

friction and will handle

higher surface velocities

than the Fiber Series.

PRODUCT DESCRIPTIONThe PolyLube Glass Tape bearing is a moderate RPM bearing designed for applications with highersurface velocities or when mixed film conditions are desired.

Similar to the Fiber Series bearing, the Glass Tape bearing is manufactured by a filament winding

process that results in a continuous fiberglass filament backing composition-ensuring excellent

mechanical properties (especially fatigue resistance) are attained. The filament wound fiberglass

structure uses a high strength, corrosion resistant epoxy resin as the matrix material. The high

strength backing permits the use of a thin wall (1/16" to 1/8") bearing which can often reduce the

size and weight of the finished bearing as-

sembly. PolyLube Glass Tape bearings will

support a dynamic bearing load of 7,000 PSI,

while handling high radial and longitudinal

stresses with a static bearing capacity of40,000 PSI. This family of materials exhibits

exceptional dimensional stability and per-

formance predictability over wide tempera-

ture ranges (325F).

PRODUCT SCHEMATICThe PolyLube Glass Tape lined bearing is similar in backing construction

when compared to its sister product-the Fiber Series bearing; however, the

difference in the construction of the liner material drives the variations in

performance. The primary performance variations between the Glass Tape

and the Fiber Series bearing are that the Glass Tape bearing has a lower co-

efficient of friction and will handle higher surface velocities. However, the

Glass Tape bearing sacrifices some capabilities with a slightly lower dy-

namic and static load capacity.

These differences are driven from fact that the Glass Tape bearing uses a

proprietary filled PTFE resin structure as opposed to the continuous PTFE

filaments used in the Fiber Series product. Two liner thicknesses are avail-

able with the 0.015" thick liner being standard and a 0.030" thick liner

being available for unique applications. The 0.030" thick liner is designedfor applications where boring the inner diameter might be required in order

to achieve tighter tolerances in an effort to address sizing and minor mis-

alignment conditions.


17/48


HIGHLIGHTS



16

MECHANICAL AND PHYSICAL PROPERTIESThe PolyLube Glass Tape bearing can withstand static loads of approximately 60,000 PSI and7,000 PSI under dynamic loading. At these loading levels, minimum distortion will occur. For dry

running applications, the maximum speed is approximately 80 surface feet per minute.

BEARING MANUFACTURER AND TYPE

RESULTS FOR VARIOUS BEARINGS TESTED BY RENSSELAERP=200 psi (constant)

AVG.

COEFFICIENTOFFRICT

ION

0.00

0.05

0.10

0.15

0.20

0.25

Metal BackedBearing

Legacy EraFW Bearing

PolyLubeFiber Bearing

PolyLube BronzeTape Bearing

PolyLube GlassTape Bearing

BEARING MANUFACTURER AND TYPE

RESULTS FOR VARIOUS BEARINGS TESTED BY RENSSELAERP=200 psi (constant)

AVERAGEPV

LIMIT

0.00

20,000

40,000

60,000

80,000

Metal BackedBearing

Legacy EraFW Bearing

PolyLubeFiber Bearing

PolyLube BronzeTape Bearing

PolyLube GlassTape Bearing

Testing performed independently at Rensselaer Department of Mechanical Engineering

COMPARATIVE PV and COEFFICIENT OF FRICTION TEST RESULTS


18/48


HIGHLIGHTS



The PolyLube bearing

offers a more elastic,

damage tolerant structur

when compared to tradi-

tional metallic bearingmaterials.

MECHANICAL AND PHYSICAL PROPERTIES (CONTINUED)This bearings operating temperature range is 325F. Maximum continuous operational surfacetemperature for the standard formulation is 325F, depending upon load characteristics. The bear-


the bearing during operation. In a free state, the coefficient of expansion of the PolyLube Glass

Tape bearing is approximately 7 x 10-6 in/in/F, similar to the coefficient of expansion for steel,

and actually less than some metals.

POLYLUBE GLASS TAPE BEARINGAPPLICATIONSApplications for PolyLube Glass Tape Bearings range

from guide rod bushings to linear motion compo-nents to hydraulic pumps. Swashblock mounted

bearings are ideal applications for the Glass Tape

bearing material as long as application considera-

tions are consistent with a mixed film condition.

The PolyLube bearing offers a more elastic, damage

tolerant structure when compared to traditional

metallic bearing materials. In addition, the Glass

Tape bearing exhibits good cavitation resistance

when subjected to high pressure fluids during

cyclic conditions.

DESIGNING AROUND STICK-SLIP (STICK-TION) WITHPOLYLUBE GLASS TAPE BEARINGSStick-slip, commonly referred to as stick-tion, is a phenomena many OEMs experience when de-

signing with self-lubricated bearings. This condition can be alleviated through a design change

from the PolyLube Fiber bearing to a PolyLube Tape bearing material.

Stick-Slip in self-lubricated bearing can be attributed to a number of factors that all have a direct

relation to the coefficient of friction between the bearing liner and the shaft. Among these factors

is the surface finish of the shaft, the pressure exerted on the bearing, the type and structure of

the bearing liner in use, and any contamination present on the interface between bearing and pin.The attributes of the bearing liner itself also contribute significantly to the stick-slip condition.

Two of these attributes include the presence of a solid lubricant in the resin (MoS2, Graphite,

etc.), and the amount of resin present at the surface that must be worn through in order to have

intimate contact between the PTFE in the bearing liner and the pin itself.



Temperature Range (Standard Formulation) 325FCoefficient Of thermal Expansion (in/in/F) 7 x 10-6







19/48


HIGHLIGHTS



18

DESIGNING AROUND STICK-SLIP (STICK-TION) WITH

POLYLUBE GLASS TAPE BEARINGS (CONTINUED)The surface finish of the shaft relates directly to

the coefficient of friction at the interface between

the shaft and the bearing. Polygon recommends a

shaft with a surface finish between 16 and 32 Ra.

In applications where stick-slip is especially sen-

sitive, a shaft with a surface finish approaching

16 Ra should be used. This will be extremely im-

portant when the Fiber liner is used with pres-

sures less than 6,000 psi. The reduced surface

finish relates to the depth the peaks on the sur-

face of the shaft embed into the bearing liner. Arougher surface finish will force larger peaks of

the shaft to be dragged through the liner. This

causes the breakaway friction to be increased ini-

tially. Using the PolyLube Fiber liner at pressures

greater than 6,000 psi will force both the shearing of the peaks and the filling of the valleys with

PTFE to occur significantly faster due to the increased shear stress. The PolyLube Tape liner will

not be as sensitive to surface finish due to the softness of the liner in contrast to the standard

Fiber liner. The tape will fill in the valleys on the surface to build up the shaft surface as opposed

to shearing the surface down slightly.

The pressure exerted on the bearing is inversely proportional to the coefficient of friction between

the bearing surface and the shaft. As the load is increased, the coefficient of friction decreases.This is due to the properties of the PTFE contained in the liner. Applications that exert a pressure

above 6,000 psi will usually not experience the stick-slip problems when using the Fiber liner. Ap-

plications sensitive to stick-slip that exert pressures below 3,000 psi should use a filled PTFE

Tape liner. This suggests that if the pressure exerted on the bearing is between 3,000 and 6,000

psi, the bearing length should be adjusted to achieve the proper pressures.

Some applications will generate a noise problem which is the result of a non-optimized design re-

lationship between the type of bearing liner, PV and pin conditions. Noise is a symptom of coeffi-

cient of friction being amplified through the entire bearing assembly. A PolyLube Fiber liner can

generate noise due to the interaction of all of the above variables. One design option is to lengthen

the bearing to bring the pressure down to approximately 4,000 psi. Such a modification will allow

Polygon to specify the tape liner. Most times, the noise problem can be solved as a result of thedrop in the coefficient of friction.

Applications sensitive to

stick-slip that exert

pressures below 3,000 psi

should use a filled PTFE

Tape Liner.

PTFE WITH WEARRESISTANT MATERIAL

WEAVE

HIGH STRENGTHCOMPOSITE FIBERGLASS

EPOXY BACKING

WEAR RESISTANT DEBRISLAYS IN VOIDS

EXPOSED PTFEREDUCES FRICTION


20/48


HIGHLIGHTS



Under start-up condi-

tions, the coefficient of

friction of the tape liner

is significantly lower.

DESIGNING AROUND STICK-SLIP (STICK-TION) WITH

POLYLUBE GLASS TAPE BEARINGS (CONTINUED)The differences between the PolyLube Fiber and Tape liners are primarily load capacity and fric-

tional response. Under start-up conditions, the coefficient of friction of the tape liner is signifi-

cantly lower. This is a result of the compositional and structural differences between the two

liners. The tape bearings use a liner that is a filled PTFE tape that creates a PTFE rich wear surface

immediately. The Fiber liner uses a uniquely designed and proprietary woven architecture of high-

tenacity PTFE monofilaments that are capable of handling higher pressures but has an epoxy

resin that migrates to the surface as a result of the manufacturing process. The epoxy resin pres-

ent at the surface will increase the coefficient of friction to about 0.2. The elevated coefficient of

friction of the Fiber liner with respect to the tape liner is not solely based on this difference.

Polygon has the ability to hone the Tape liners if required for unique applications. This honing fea-ture allows the Tape lined bearings to have a coefficient of friction that is about 0.1 during start-

up conditions. The trade-off for this low coefficient of friction is load capacity. Polygon has rated

the Tape bearing to have a maximum operating pressure of 4,000 psi. In comparison, the PolyLube

Fiber lined bearings can operate as high as 20,000 psi (design thresh-hold).

The presence of solid lubricants alone does not solve the whole stick-slip

problem. Such a design concept is similar to an initial greasing with a

greased bearing. Greasing will simply prolong the break-in process until

the lubricant is used up or pushed out. Noise can develop after the lubri-

cated layer of resin was penetrated and the PTFE fiber wear surface was in

intimate contact with the pin. The noise phenomenon is due to the abra-

sive nature of the PTFE filaments.

The designed pressures and the choice of liners are critical in applications

that have an increased sensitivity to stick-slip. The major design criteria

would be to use the Tape liner if a bearing can be used that will keep the

pressures to 4,000 psi or below. If the pressures must be designed higher

than 4,000 psi, a bearing length should be used to keep the pressures

above 6,000 psi. This will enable the Fiber bearing to be used with a

greater probability of success as it relates to stick-slip.

PTFE

BRONZEPARTICLES

DRY LUBRICANTFILLERS

TAPE (BRONZE) BEARING

GLASSFILAMENTS

GLASS TAPE BEARING


21/48


HIGHLIGHTS

IFR BEARINGSELF LUBRICATED COMPOSITE BEARINGS


20

PRODUCT DESCRIPTIONThe PolyLube IFR bearing offers the same inherentanti-friction components that allow it to achieve the

low wear characteristics of the Fiber and MRP series

bearings. However, in comparison to these two prod-

ucts, the IFR bearing (for Improved Fatigue Resist-

ance) offers a proprietary laminate structure of the

bearing backing that increases the bearings resist-

ance to repeated stress/strain conditions.

Several years ago, Polygon Company was approached with a seemingly straight-forward applica-

tion for traditional filament wound composite bushings. At issue was an application that was re-

sulting in bearing failure after just 10,000 oscillatory cycles. The pressure on the bearing was

well under the design threshold (actual applied pressure to the bearing was 10,000 PSI). In re-sponse to this customers demand, Polygon Company developed an improved impact fatigue

bearing that in the case of the above application, increased the life of the bearing by over 50%.

Because composite filament wound bearings are not isotropic

materials as are metals, Polygon Companys FEA laminate

analysis focused on what was believed to be the limiting factor:

optimization of systems interlaminar shear. The PolyLube IFR

bearing offers a more than twofold increase in the impact fa-

tigue over traditional composite bearing materials.

PRODUCT ADVANTAGESThe PolyLube IFR bearing is the first bearing with such an opti-

mized resin system and fiber/laminate architecture.

The PolyLube IFR bearing

offers a proprietary struc-

ture that improves resist-

ance to fatigue failure.

CONTINUOUS FIBERGLASSFILAMENT WINDING

= WIND ANGLE

40

60

20

STRENGTH PROPERTIES AT VARIOUS WIND ANGLES

WIND ANGLE

STRENGT

H(ksi)

20 40 60 80 100

80

FxT ksiFyT ksiFxC ksi

FyC ksiFxy ksi

100

120

140

160

1

MODULUS OF ELASTICITY AT VARIOUS WIND ANGLES

WIND ANGLE

E

LASTICMODULUS(Msi)

20 40 60 80 100

2

Ex MsiEy MsiGxy Msi

TraditionalWind Angle

PolyLubeHigh StrengthWind Angle



3

4

5

6

PRODUCT SCHEMATICTraditional filament wound composite bearings will tend to show fatigue failure in the formof resin shear failure in the traverse direction to the reinforcing fibers. The logical solutionto this problem was to try to cross-tie the reinforcing fibers together with other reinforcingfibers so as to minimize the shear stresses in the resin.

A low friction, self-lubricating composite bearing withsignificantly improved fatigue resistance against re-peated stress/strain conditions.


22/48

HIGHLIGHTS

SELF LUBRICATED COMPOSITE BEARINGS


MECHANICAL AND PHYSICAL PROPERTIESThe PolyLube IFR bearing can withstand static loads of approximately 60,000 PSI and 30,000 PSIunder dynamic loading. At these loading levels, minimum distortion will occur. For dry running ap-

plications, the maximum speed is approximately 10 surface feet per minute.

This bearings operating temperature range is 325F. Maximum continuous operational surface

temperature for the standard formulation is 325F, depending upon load characteristics. The bear-


the bearing during operation. In a free state, the coefficient of expansion of the PolyLube IFR bear-

ing is approximately 7 x 106 in/in/F, similar to the coefficient of expansion for steel, and actually

less than some metals.

POLYLUBE IFR BEARING APPLICATIONSExcellent applications for IFR bushings include bearing systems using alloyed bronze, spring-

retained, hardened bushings and hardened steel bearings.

Ex(axial), Msi

Ex(hoop), Msi

Gxy, Msi

Tx(tensile), Ksi

Tx Ksi

Cx(compression), Ksi

V-xy(Poissons Ratio)

V-yx

1.3

3.2

1.0

5.5

64.5

18.8

.314

.762

1.6

2.4

1.0

11.9

48.7

20.0

.312

.435

MECHANICALPROPERTIES

POLYLUBE FIBER ORMRP SERIES BEARING

POLYLUBE IFRBEARING

This picture represents the initial on-set codition commonly related to fatigue failure du

to repeated impulse loading of the bushing.Composite bearings that do not have an optimized resin system and laminate architectuwill be very susceptible to this type of failure

POLYLUBE Design guideIFR BEARING


23/48


HIGHLIGHTS

HIGH TEMPERATURE BEARINGSELF LUBRICATED COMPOSITE BEARINGS


22

PRODUCT DESCRIPTIONThe PolyLube HT bearing is a high load, low RPM bearing de-signed for applications where self-lubrication is desired, but

conventional composite bearings will not perform at high

temperatures. This product has been designed to provide

excellent performance at elevated temperatures. With a

glass transition temperature of over 450F this epoxy fila-

ment wound structure exhibits superb performance over

extended exposure to elevated temperatures. The bearing

material is focused on applications where the bearing will

be exposed to temperatures up to 450F.

In addition to its high compressive properties (in both static and dynamic modes), this bearing

material is inherently self-lubricating. The self-lubrication capability of Polygons new materialmeans that the use of expensive high temperature external lubricants such as polyurea grease,

lithium grease, some bentone greases, as well as advanced ester based oils and complex thicken

ing systems may no longer be necessary.

The PolyLube HT bearing creates a high strength, self-lubricating journal bearing material that can

offer performance enhancements over greased systems, as well as graphite loaded bronze struc-

tures, some iron-copper graphites, polysulfone, PEEK, and polymide bearing materials.

PRODUCT SCHEMATICThis bearing is based on the same filament wound structure as the PolyLube Fiber Series bearing

and has the same wear liner. The result is that the HT bearing has a high static and dynamic load

capacity. The HT bearing is also inherently self-lubricating through the same film transfer process

as the Fiber Series bearing.

The result of a higher temperature

resin matrix, the same high strength

filament wound backing, and the same

self-lubrication process combine to

make the HT bearing an ideal solution

for high temperature applications.

The PolyLube HT bearing

can offer performance

enhancements over greasedsystems, as well as polysul-

fone, PEEK, and polymide

bearing materials.

The PolyLube High Temperature bearing was originated from developmentwork the company was doing on high temperature, high RPM, high radiallystressed composite materials for ring reinforced commutators. The end wasreplacing steel-mica rings with a high strength composite material.


24/48


HIGHLIGHTS

HIGH TEMPERATURE BEARINGSELF LUBRICATED COMPOSITE BEARINGS


MECHANICAL AND PHYSICAL PROPERTIES

**Note: These are typical properties. Specific properties may vary, depending on the composite design for each application.

APPLICATIONSPolyLube High Temperature applications are not just

for elevated temperature environments but also for

applications where the bearing may need to resist

thermal expansion during operation. One example of

this is in snowmobile clutch markets. In these appli-

cations, the clutch speed goes from 0 to very high

RPMs in micro-seconds (and vice versa). During this

cycling, friction is rising because speed is being dra-

matically increased. As the friction goes up so doesthe temperature of the associated components. A

high temperature composite bearing material can re-

sist these expansion phenomena and as a result

offer better long term wear, improved bearing durabil-

ity, and less seizure opportunity than conventional

metal bearing materials.

Ultimate Compression Strength (PSI) 60,00 0


Temperature Range 200C





PHYSICAL PROPERTIES**

Hoop Strength (Fy x 103) 120

Tensile Strength (Ft x 103 PSI) 20

Flexural Strength, Axial (Fbx x 103 PSI) 20

Poissons Ratio, Axial 0.08

Shear Modulus (Gxy x 106 PSI) 0.6

Elastic Modulus (Ex x 106 PSI) 0.6

Elastic Modulus, Transverse (Ey x 106 PSI) 5.0

THERMAL PROPERTIES**

Thermal Conductivity (BTU/hr/sq ft/F/in) 1.8 to 2.3

Specific Heat (BTU/lb/F) 0.27

Coefficient of Thermal Expansion (in/in/F) 5.0 to 7 x 106

Heat Resistance, Continuous 200C

ELECTRICAL PROPERTIES**

Insulation Resistance (ohm/8" length) 2.38 x 1012

Volume Resistivity (ohm/cm) 2.41 x 1015

Surface Resistivity (ohms) 2.92 x 1015

Dielectric Strength, Short Time (volts/mil)Minimum 100

Dielectric Constant (60 cps) 4.15Dissipation Factor (60 cps) 0.0094

Impulse (11/2 40u Wave (Axial) volts/mil) 400 to 550

Power Factor @ 60 cps (100v pct mx)

As Received 5.0

@100C 10.0

After 24 hours @100F @ 98% rel. hum. 10.0


25/48


HIGHLIGHTS

GUIDE ROD BUSHINGSELF LUBRICATED COMPOSITE BEARINGS


24

PRODUCT DESCRIPTIONPolyLube Guide Rod Bushings are de-signed as replacements for traditional

metallic guide rod bushing materials. Re-

placing conventional metallic guide rod

bushings with a PolyLube guide rod bush-

ing is a straight-forward change out. Typi-

cal replacement programs where metallic

guide rod bushings are replaced are

driven from one or a combination of sev-

eral of the following factors.

PolyLube Guide Rod Bushings are commonly available in two formats: a PolyLube bushing utiliz-

ing a sintered PTFE liner or a PolyLube bushing utilizing a PTFE fabric liner. The most commonPolyLube guide rod bushing in use today is the sintered PTFE liner due to two primary perform-

ance enhancements over the PTFE fabric lined bushing: the frictional response under start-up

conditions and the transfer of PTFE to the wear surface.

COMPARISONS TO COMMON GUIDE ROD BUSHING MATERIALSSINTERED (PM) STRUCTURE BRONZE

Sintered powder metal (PM) structure bushings rely on an internal lubricant that is entrapped

into the metallic structure as it undergoes the sintering process. As the bushing is cycled the lu-

bricant migrates to the wear surface both as a natural function of relieved internal bushing stress

which allows the lubricant to flow to the area of bushing wear, but also as the bushing itself is

worn away and the lubricant finds itself in contact with the

pin material. Several problems exist for this type of bushing

material.

First, these bushings have a poor load capacity in either dy-

namic or static conditions. In linear slide block applications,

this load capacity can become increasingly problematic. As

the load on the bushing assembly increases, the bushings

will wear to accommodate the emerging load pattern during

the bushings cycle. As this process advances, the bushing

assemblys accommodation will translate into increased slopin the slide block itself, and will ultimately result in a slide

block that is no longer cycling per the manufacturers re-

quirements as well as causing increased seal wear from

piston misalignment.

REASONS TO DESIGN WITH POLYLUBE GUIDE ROD BUSHINGS:

Improved stick-slip properties

Optimal frictional response during cycling

Significant reduction in shaft scoring

Extension in the bushing life

Reduction in bushing profile

Greatly improved side load/misalignment capacity

Increase in load capacity of bushing Enhanced corrosion resistance

Tolerance of more cost effective shaft finishes

Lower in weight

PolyLube Guide Rod

Bushings offer improved

stick-slip properties and

a reduction in shaft

scoring.


26/48


HIGHLIGHTS



COMPARISONS TO COMMON GUIDE ROD BUSHING MATERIALS (CONTINUED)Second, sinter structure bronze bushings have a lubrication mechanism that is both unreliableand easy to deplete. This means that shaft scoring, high friction, and high wear are all anticipated

with these bushing materials. PM structure bushings must wear in order to continue to transfer

lubricant to the wear surface. In linear slide applications the surface area that must be covered

with lubricant is significantly greater than what is seen in oscillatory or rotational movement envi-

ronments. As such, the frictional response and wear patterns of PM structure bushings degrade

much more rapidly than higher performance bushing materials.

METAL-BACKEDThis family of bushing materials is divided into two product types: the first is true ring structure

metal backed bushings and the second is split seam journal bushings. Ring structure bushingsare expensive to manufacture given the means by which the bushing liner is inserted into the

bushing ID. The labor required to complete this process, as well as the necessary secondary labor

to manufacture the bushing to the tolerances required, result in an overly expensive bushing.

The second type of metal-backed bushing is the more common split seam journal bushing. This

bushing exhibits good frictional response during start up conditions but is prone to excessive

wear. The PTFE overlay is very thin (typically only 0.005") and is quickly worn away in linear mo-

tion applications where the surface area

that the PTFE must be transferred to is

fundamentally greater than the surface

area of a conventional rotational or os-

cillatory application. In addition, start-up

running clearances change very quickly

in metal-backed bushings due to the

thin soft PTFE overlay on top of the

bronze inter-structure being scrubbed

off of the bushing bore surface. Strict

running clearances quickly disappear

as the liner wears and tries to stabilize.

Depending upon shaft finishes, wear

simply accelerates resulting in un-

wanted clearances and assembly loose-

ness. A PolyLube compositeself-lubricating bushing offers minimal

break-in and reliable self-lubrication

through application life.

With metal-backed jour-

nal bushings, startup run

ning clearances change

quickly due to the thin an

soft PTFE overlay on top o

the bronze interstructure

being scrubbed off the

bushing surface.


27/48


HIGHLIGHTS



26

COMPARISONS TO COMMON GUIDE ROD BUSHING MATERIALS(CONTINUED)THERMOPLASTICA common and low cost guide rod bushing material is thermoplastics. These type of bushing ma-

terials share most of the design and performance limitations that PM structure metal bushings

do because the thermoplastic bushing material itself is similar in its structure as that of a PM

metallic bushing. Thermoplastics however have two additional problems associated to linear mo-

tion environments.

First, in applications where the slide velocity is high, a thermoplastic guide rod bushing does not

tolerate the heat generated from such quick response requirements. The most common thermo-

plastic bushing grade materials will bind on the shaft and actually begin to break down mechani-

cally as the bushing is cycled. The amount of lubricant and

fillers will play a dynamic role in the relationship between

mechanical and performance degradation as it relates tovelocity.

Second, thermoplastic bushing materials are prone to cold

flow. Under constant load many thermoplastic guide rod

bushings will exhibit creep. This creep will result in slop in

the bushing assembly and will negatively effect any preci-

sion the slide block is expected to maintain.

BLACK DEBRIS SHAFT DEPOSITIONIn some linear motion application environments, a

black debris develops on the distal and proximal ends

of the shaft during normal cycling conditions. This

debris is commonly seen when a sintered PTFE lined

bushing is used.

This debris is most commonly the result of a complex

interaction between the pin material itself, the liner

selection, and the rate of deceleration of the bushing

assembly. In some linear guide applications, the

weight of the bushing assembly itself creates a

macro-mechanical edge rolling condition as the as-sembly decelerates. For a sintered PTFE lined bush-

ing (not a fabric PTFE lined bushing), this

deceleration causes parts of the bushing liner to roll

as the motion reverses itself. The nature of the resin the PTFE is entrapped within can create the

potential for the resin itself to bind against the shaft. As this phenomena is repeated, the liner will

fatigue and begin to transfer macroscopic portions of the liner onto the shaft.

In applications where the

slide velocity is high, a

thermoplastic guide rod

bushing does not tolerate

the heat generated from

such quick response

requirements.


28/48


HIGHLIGHTS



BLACK DEBRIS SHAFT DEPOSITION (CONTINUED)This debris deposition is application specific and is not seen in all application environments. Inother application environments, the black debris is seen in relation to sintered (PM) structure

bronze or brass bushings. In this case, the black discoloration is not purely a deposition of mate-

rial onto the shaft, but rather a scoring effect common to ring structure bushings that have a low

tolerance for missing lubricant or contamination.

The solution to an application where liner debris is being deposited on the shaft is to alter the

bushings wear surface to a non-resinous and non-metallic liner. In these cases, Polygon recom-

mends transfer to one of its PolyLube fabric lined bushings such as the PolyLube Fiber, MRP or Z-

Series bushings. These bushings incorporate high tenacity PTFE filaments in their continuous

architecture. This is in contrast to PTFE resinous systems which rely on either a sintered powder

form of the PTFE polymer or to another resin (such as acetal) with PTFE fibers randomly dis-

persed within the resin itself.

The PolyLube bushings that have high tenacity PTFE filaments in their architecture allow for the

bushing assembly to undergo aggressive deceleration conditions without depositing the PTFE or

the resin carrier medium onto the shaft. This is because the wear surface of the fabric lined bush-

ings utilize the filaments themselves without reliance on a resinous impregnation.

POLYLUBE ID SEAL CONFIGURATIONSIncorporating T-lip wiper seals, radial shaft seals, o-rings

or any other similar internal sealing system is not a prob-

lem for PolyLube Guide Rod Bushings. Polygons internal

fabrication capabilities allow for easy and economical in-

corporation of ID features required to install common

sealing systems.

Two liner thicknesses are available in the standard Poly-

Lube PTFE tape lined bushing configuration: the 0.015"

thick liner being standard and a 0.030" thick liner also

being available for applications where seal geometry

might require the introduction of a thicker liner to accom-

modate a unique ID feature. The 0.030 thick liner can

also be used in applications where boring the ID might berequired in order to achieve tighter tolerances in an effort

to address sizing and minor misalignment conditions.

The solution to an appli-

cation where liner debris

is being deposited on the

shaft is to alter the

bushings wear surface to

a non-resinous and non-

metallic liner.


29/48


HIGHLIGHTS



28

POLYLUBE FABRICATION CAPABILITIESOne common fabrication detail seen on guide rod bushing appli-cations deal with corner radiuses on internal and external

grooves. Because Polygon uses a diamond wheel or groove tool

to form the grooves we need to have at least a .015-.020" corner

radius. When threads are used there is usually clearance in-

volved. When assembled with the mating part the bushing could

shift to one side or the other impacting the location of the bush-

ing surface in relation to the piston shaft. This could have a nega-

tive impact on wear.

The only other fabrication issue commonly seen on incoming prints is a surface finish called out

on the internal diameter. This is typically related to an OEMs historical use of machined bronze

bushings in the application. Since the bronze is machined from a solid piece or casting, the sur-face finish is called out since it is related to the speeds and feeds of their fabrication process. The

wear surface on PolyLube bushings is not machined so the surface finish call out can be removed

from fabrication requirements.

Polygon is capable of holding a TIR I.D. to O.D. within .002" and straight diameters to +/-.0005".

MECHANICAL AND PHYSICAL PROPERTIESPolyLube Guide Rod bushings are manufactured by a filament winding process that results in a

continuous fiberglass filament backing ensuring excellent mechanical properties (especially fa-

tigue resistance). The filament wound fiberglass structure uses a high strength, corrosion resist-

ant epoxy resin as the matrix material. The high strength backing permits the use of a thin wall

(1/16" to 1/8") bushing which can often reduce the size and weight of the finished bushing as-

sembly. This family of materials exhibits exceptional dimensional stability and performance pre-

dictability over wide temperature ranges (325F).

The high strength backing

permits the use of a thin

wall (1/16" to 1/18")

which can often reduce the

size and weight of the

finished bushing.


30/48


HIGHLIGHTS



MECHANICAL AND PHYSICAL PROPERTIES (CONTINUED)This bushings operating temperature range is 325F. Maximum continuous operational surfacetemperature for the standard formulation is 325F, depending upon load characteristics. The bush-


the bushing during operation. In a free state, the coefficient of expansion of the PolyLube Guide

Rod Bushing is approximately 7 x 10-6 in/in/F, similar to the coefficient of expansion for steel,

and actually less than some metals.

POLYLUBE SINTERED PTFE LINER



Temperature Range (Standard Formulation) 325F






POLYLUBE PTFE FABRIC LINER



Temperature Range (Standard Formulation) 325F







31/48


HIGHLIGHTS

BEARING DESIGN PRINCIPLESSELF LUBRICATED COMPOSITE BEARINGS


30

PV CALCULATIONSPV (Pressure & Velocity) is the most common empirical tool to use when comparing and contrast-ing bearing performance. P is related to pressure or pounds per square inch on the projected

bearing area, while V is velocity in feet per minute of the wear surface. Knowing the PV limit of a

bearing, the designer can determine the loads and surface running speeds under which a bearing

can safely operate. Since heat generated by friction is one of the major causes of degradation in

liners, evaluation of the operating conditions of a fiberglass-reinforced, composite journal bearing

requires that you know the approximate temperature generated on or near the actual wear sur-

face. The temperature rise is also dependent on the running speed and is not a linear function of

the PV product.

AS A GUIDELINE, POLYGON SPECIFIES A 20,000 PV LIMIT FOR THE POLYLUBE BEARINGS. TEST

RESULTS CONDUCTED AT 15,000 PV GAVE ONLY 0.002" WEAR AFTER 10 MILLION CYCLES, 25

OSCILLATION RUN AT 60 CPM AND 343 POUNDS RADIAL LOAD. FOR SPECIAL APPLICATIONS,50,000 PV IS POSSIBLE.

BEARING

PROJECTEDAREA

FDFL

Ft

Fd FLT

D

L

BEARING

SHAFT

SHAFT

BEARING

AREA = L x D

PRESSURE =FORCE

AREA

VELOCITY IN FEET/MIN =D

12x RPM

PV = PRESSURE x VELOCITY

FORCE

CALCULATING SLEEVE BEARINGPV LIMIT

EXAMPLE: .750" Shaft @200 rp

85.0 lb. total load, bearing

length .750"

V = 0.262* x rpm x diameter

= 0.262 x 200 x .750 = 39.3 fpm

P = total load / projected area (A)**

A = .750 (shaft) x .750 (bearing

length) = .562 in.2

P = 85.0 lbs. / .562 in.2

= 151.2 psi TDTd

D = Flange Diametert = Flange Thicknessd = Bearing Inside DiameterL = Flange Length

SLEAVEBEARING

FLANGEDBEARING

THRUSTWASHER

Additional calculations for flanged bearings & thrust washers follow:

FOR A PRACTICAL ILLUSTRATION OF APPLIED AND DEFINED PV CALCULATIONS, REFERENCETHIS ILLUSTRATION:

d L

BEARING

PROJECTEDAREA


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LENGTH RATIOOptimum performance can be achieved by specifying a length to inside diameter ratio (L/ID)ranging from 0.5 to 2.0. Below an L/ID of 0.5, highly stressed areas at the bearings corner may

cause premature cracking. If the L/ID ratio is higher than 2.0, a small shaft misalignment could

cause cross-corning jamming. At this point, the units radial and/or longitudinal stresses could ex-

ceed 30,000 PSI. However, bearings constructed with the proper L/ID ratio can accept misalign-

ment and shock loads without premature failure.

MISALIGNMENT CONDITIONSMany applications undergo regular stressing of the bearing corners due to a misalignment condi-

tion. Should that condition be irregular, the existing PolyLube series bearings are acceptable. It is

important; however, to understand how misalignment impacts bearing performance and whatconditions are identified and analyzed by Polygons PolyLube application engineers. Misalignment

conditions create a non-linear pressure area and significantly increase the edge stresses on the

bearing. As a result, premature fatigue cracking can occur. The schematic below illustrates both

conditions. For PolyLube bearings, concerns with edge stress and fatigue cracking become acute

as the effective misalignment increases to 0.015 in/in. Beyond that level, a different backing con-

struction can be used to increase the bearings resistance to impact and resulting fatigue.

Properly designed composite bearings can accommodate edge loading

above other bearing materials. As a result of the high strength but elastic

fiberglass backing, PolyLube bearings can handle up to a 0-51' -34" angle

misalignment.

A A

B B

SHAFTANGLE

BEARINGLINEAR

PRESSUREAREA

A-A PRESSURE

B-B PRESSURE

ANGLE EFFECTIVE MISALIGNMENT

0 - 13' - 45" ............................0.004 in./in.

0 - 20' - 38" ............................0.00 6 in./in.

0 - 34' - 23" ............................0.010 in./in.

0 - 51' - 34" ............................0.015 in./in.

A A

B B

SHAFTANGLE

PARABOLICPRESSURE

AREA

BEARING

A-A PRESSURE

B-B PRESSURE

Linear pressure areasare indicative of a slightmisalignment condition.

Parabolic pressureareas are indicativeof a gross misalign-ment condition.

Many applications un-

dergo regular stressing of

the bearing corners due to

a misalignment condition


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HIGHLIGHTS



32

DESIGNING FOR EDGE LOADINGAs with liner construction, in order to optimize acomposite bearings impact resistance, the bear-

ing must also take advantage of the performance

drivers that are related to the wind angle of the

fiberglass backing. The fiberglass backings orien-

tation off of the neutral axis is a significant driver

in the finished performance of the bearing itself. Most composite bearing companies utilize wind-

ing equipment that produces bearings between a 40 and 55 degree wind angle. For most applica-

tions this is acceptable; however, for applications where repeated high stress/strain is of concern,

the backing can be further optimized by positioning the wind angle closer to a theoretical 90 de-

gree wind angle. This type of performance optimization is what Polygon does that other compa-

nies do not. Our manufacturing equipment is all precisely computer controlled and as a result,

wind angles can be modified to accommodate higher impact resistance.

For further information

on impact fatigue and the

technical bulletin on liner

construction contact a

PolyLube product engineer.

1

MODULUS OF ELASTICITY AT VARIOUS WIND ANGLES

WIND ANGLE

ELAST

ICMODULUS(Msi)

20 40 60 80 100

2

Ex MsiEy MsiGxy Msi



3

4

5

6

40

60

20

STRENGTH PROPERTIES AT VARIOUS WIND ANGLES

WIND ANGLE

STRENGTH(

ksi)

20 40 60 80 100

80

FxT ksi

FyT ksiFxC ksiFyC ksiFxy ksi

100

120

140

160



CONTINUOUS FIBERGLASSFILAMENT WINDING

= WIND ANGLE

The result of an ability to optimize perform-ance is that conditions of high edge loadingcan be better controlled and designed aroundby utilizing Polygons design skill. This allowsfor a direct translation between theoreticallaminate theory, the manufacturing process it-self, and the performance of your product.


34/48


HIGHLIGHTS



LOAD CAPACITYPolygons proprietary process of fiberglass filament winding results in exceptionally strong struc-tures that can support the bearing surface more than adequately. Loading in excess of 30,000

PSI can be tolerated in many situations, provided the design and the conditions of service are

fully outlined and analyzed by a Polygon bearing specialist. Fatigue is not a limiting factor in the

use of PolyLube bearings. Frequent laboratory tests have shown that the bearing is often more fa-

tigue-resistant than the shaft.

BEARING WEARDuring the initial break-in period of a

PolyLube bearing, a transfer film is

created on the mating surface. Insome operations, as much as 0.001"

of wear may occur during this period,

while in other operations, break-in

wear may be negligible. For more de-

tail on the break-in period and the

mechanism by which each bearing

achieves sufficient film transfer, refer

to the respective product inserts.

ASSEMBLYWhen a PolyLube bearing is press fit into a housing, it expands into the housing and creates a

highly loaded press fit condition. This is possible because of the elastic properties of the bearings

backing material. Press fits on wall thicknesses up to 1/8" have demonstrated that the close-in

ratio is one-to-one (0.001 press yields a 0.001 close in). However, press fits should be mini-

mized, even though the tube will readily take presses of 0.004" to 0.005". The use of a standard

H7 housing bore is also recommended.

DEFLECTION VS. LOAD

RADIAL DEFLECTION, INCHESChart represents typical deflection and permanent set for heavy wall POLYLUBE bearings

STATICRADIALLOAD,

PSIx10

3

PSI

50

40

30

20

10

.004 .008 .012 .016 .020 .024 .028 .032

Deflection

TYPICAL VALUES FORPGP16F24-8

(LOADING RATE, 10,000 PSI/MIN)

Permanent Set

POLYGON POLYLUBE FIBERPV=11,416 CONTINUOUS ROTATION

TIME IN HOURS

WEARININCHES

0.0005

25 50 75 100 125 150 175 200 225 250

0.001

0.0015

0.002

0.0025

0.003

0.0035


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HIGHLIGHTS



34

The thinner the wall, the

greater the transfer of

heat.

ASSEMBLY (CONTINUED)Due to thermal lag, the bearing wear surfacemay be hotter than the adjacent housing,

when heat is generated from running friction.

As a result, the installed bearing may expand

inward, reducing the shaft clearance. For opti-

mum performance. Polygon recommends a

smooth, hardened steel shaft with a 16 micro

finish. However, PolyLubes rugged bearing surface will permit use of a rougher finished shaft,

such as a standard drill rod, if the bearing to shaft clearance is increased. (See Part # listings for

recommended shaft clearances).

Shaft clearances should be increased for dry running applications with high rubbing velocities. Fluid

cooling and lubricants will reduce the operating temperatures, permitting tighter shaft clearances. Heatransfer through the bearing wall is inversely proportional to the wall thickness. The thinner the wall,

the greater the transfer of heat. Thermal conductivity, for example, is 1.8 to 2.3 Btu in/(hr ft2 F).

SYSTEM LUBRICATION INFORMATIONSince lubrication is inherent in the bearing su

polylube design-guide copy

Documents

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polylube ifr bearings

polylube glass tape

polylube fiber series

polylube guide rod bushings

bearing design principles

mrpsl bearings

low wear