DSM Engineering Plastics

DS

ME

N G

I N

E E

R I

N G

P

L A

S T

I C

S

1

Contents

DSM: A Pioneer in Wear and Friction Resistant Thermoplastic Materials for Over 50 Years 2

Tribology: A Science in Motion 3 Wear 3Friction 4

Wear and Friction Measurement Techniques 5Test procedure 5Test data and significance 6Multiple point test data 8

Thermoplastic Polymers 11Thermoplastics 11Crystalline thermoplastics 11Amorphous thermoplastics 12

Lubricants 13Internal lubrication 13Polytetrafluoroethylene (PTFE) 13Polymethyldisiloxanes 14PTFE and Silicone 15Binary lubricant packages 15Molybdenum Disulfide (moly) 16

Reinforcements 17Glass fiber 17Carbon fiber 17

Plastic on Plastic Wear 18

Using Tribological Data for Material Selection 19

Key Tribological Application Parameters 21

Typical PV Situations and Material Selection 22

Key DSM Tribological Grades 23

DSM Engineering Plastics is aBusiness Group in the performancematerials cluster of DSM, with sales in2001 of $558 million (Euro 603 million)and approximately 1,350 employeesworldwide. It is one of the world’s lead-ing players in the field of engineeringthermoplastics offering a broad portfolioof high performing products.

DSM Engineering Plastics operates in allmajor markets of the world including theAmericas, Asia, and Europe. Withineach region customers can count on ourinnovative research, development, andsupport facilities. Our in-houseresources are backed by a corporateresearch and development center that isutilized in creating new solutions forcustomer needs. The advanced level ofaccount management, in combinationwith our effective global communicationnetwork, secures the support customersneed wherever it is required.

With polymerization and compoundingfacilities for a range of polyamides,polyesters, polycarbonates, and UltraHigh Molecular Weight PE and extrud-able adhesive resins, we serve our glob-al customer base and assure a constant,reliable supply of products.

All our compounding facilities in theworld (in the Netherlands, Belgium,USA, Canada, China, and India) arebeing expanded continuously to keepup with the growing demand.

As a result of a constant product innova-tion and creation process, DSMEngineering Plastics can offer a cohesiveportfolio of high performing engineeringplastics. Established trade names are:

Akulon® (nylons)Akulon® Ultraflow™ (a high flow nylon 6)Arnite® (thermoplastic polyester)Arnitel® (copolyester elastomers)Stamylan® UH (UHMWPE)Stanyl® PA46 (PA46)Stanyl® PA46 High Flow™ (high flow PA46)Stapron® (PC-blends)Xantar® (polycarbonate)Xantar® C (PC/ABS-blends)Yparex® (extrudable adhesive resins)

Complemented in some regions byproducts such as:

Electrafil® (conductive thermoplastics)Fiberfil® (reinforced & filled thermoplastics)Nylatron® (lubricated thermoplastics)Plaslube® (lubricated thermoplastics)

These materials all have their specificproperties, yet they share the same highquality thanks to state-of-the-art produc-tion processes and quality systems likeTotal Quality Management, ISO 9001,and QS 9000.

It’s an approach to quality that can befound throughout the DSM organization:

- in relations with industry partners,working closely together in truecooperation, ready to meet any tech-nical challenge

- in technical service and after sales,providing support to help customersoptimize their processes

- in logistics and delivery, shippingproducts anywhere in the worldquickly and reliably.

From product concept, through pro-cessing, to final application, DSMEngineering Plastics brings the portfolio,skills, and global presence to help itsindustrial partners create world-classproducts and solutions.

DSM is active worldwide in life scienceproducts, performance materials, andindustrial chemicals. The group has annu-al sales of close to $5.5 billion (Euro 6 billion) and employs about 20,000 peopleat more than 200 sites worldwide. DSMranks among the global leaders in manyof its fields. The company’s strategic aimis to grow its sales (partly through acqui-sitions) to a level of approximately $9.2billion (EUR 10 billion) in 2005. By thattime at least 80% of sales should be generated by specialties, i.e. advancedchemical and biotechnological productsfor the life science industry and perform-ance materials.

2

For more than 50 years, DSM technol-ogy and expertise have enabled plas-tics engineers to incorporate morevalue and innovation into their designs.The broad DSM product portfolio ofengineering thermoplastic resins andcompounds allows designers thegreatest flexibility in solving wear andfriction design challenges.

The use of engineering thermoplas-tics in self-lubricating dynamic partshas revolutionized virtually everyindustry and application since theirintroduction. Designs not previouslypossible in other materials havebecome commonplace using theseunique engineering materials.

Internally lubricated thermoplasticsoffer many benefits over standardplastics. Those benefits include:

- elimination of the need for external lubrication

- improved load bearing capabilities- reduced wear rates- lower and more consistent

frictional responses- elimination of "stick-slip"- elimination of "chatter" and other

motion-induced noise

- reduced part weight and inertial mass

- cost savings due to parts consolidation

- elimination of secondary finishing operations.

Plastics are a relatively new engineer-ing material and our understanding oftheir capabilities, especially comparedto metals, is still an evolving science.As we approach the performance limi-tations of polymer resins in thesedemanding applications, the need tospecifically modify them for increasedutility becomes necessary. As always,knowing precisely what is expected ofa material for an application is requiredto determine the most effective cost-to-performance balance demanded bycurrent designs.

This brochure is designed to assistthe plastics parts designer in under-standing the fundamentals of polymerwear and friction. The methods ofcharacterizing these tribological prop-erties, as well as the effective inter-pretation of these results in relatingtheir use to dynamic applications, willbe explored. In addition to informa-tion about individual material capabili-

ties, we will examine the complexinter-relationship of application condi-tions to the successful operation ofdynamic thermoplastic parts.

DSM: A Pioneer in Wear and Friction ResistantThermoplastic Materials for Over 50 Years

The first significant use of a thermoplastic inside of an automobile

engine block, the Valve Lifter Guide has revolutionized valve train

technology since its introduction by Mid-American Products, Jackson,

MI in 1991. Manufactured exclusively from Nylatron® internally

lubricated thermoplastics and Stanyl® PA46, this part significantly

reduces valve lifter radial shuck, an important cause of engine noise.

This single thermoplastic part replaced the previous eight metal ones

and allowed for simplified assembly techniques at a substantial cost

savings. Now found in many major domestic engines, these DSM

materials have the long term wear, temperature, and chemical

resistance to survive this very aggressive operating environment.

Tribology is the science and practicesrelating to the interactions of surfacesin relative motion. Due to concernsabout durability, component reliability,and design integrity, this new scienceis gaining increasing importance in thedesign of many mechanical products.

Wear

The progressive loss of material due tothe dynamic interactions of two sur-faces in relative motion contact isknown as wear. Some common appli-cations rely on the steady and progres-sive wear of one material againstanother; pencil graphite (lead) againstpaper, for example. For most mechan-ical applications, however, the wearloss of material surfaces is a functionalliability. For example, the loss of onlyseveral grams of material from theoperational parts of an automotiveengine is enough to cause a total func-tional cessation of a 4,000 pound vehicle.A commonly expressed goal for manydesigns is either the total elimination oran absolute minimum of wear. In prac-tice, cost constraints usually dictatethat the designed part exhibit anacceptable amount of part wear overthe projected life of the part.

There are several recognized types ofwear, each with a unique modality andresulting in varying amounts andforms of material removed during theprocess. Usually one form is preva-lent. Typically, though, most relativemotion wear is a combination of thefollowing types of wear:

- adhesive- abrasive- fatigue- corrosive.

Adhesive wear. The predominantform of polymer wear is adhesivewear which is characterized by theformation of fine powder debris.Initially, a momentary adhesive junc-tion is formed between the polymerand mating surface. This junction isformed either through physical attrac-tions, such as van der Waals forces,or by thermal softening or melting atthe surface. Still other mechanismsinvolve material transfer through lami-nar shear or cold drawing.

This wear type is also characterizedby the formation of transferred poly-mer film to the usually harder coun-terface surface. The generation andsuccessful maintenance of this filmusually results in a low equilibriumrate of wear.

Abrasive wear. When deformationof the polymer surface exceeds theelastic limits of the material abrasivewear occurs. It is characterized by thecutting, plowing, or tearing of the poly-mer by the harder asperities of themating counter-surface. This mecha-nism is determined by the actual con-tact stresses, as well as mating sur-face characteristics such as surfacehardness and finish.

In addition, the presence of hard "thirdbody" particles, such as sand or metaldebris that are trapped between mov-ing surfaces, contribute to the abrasivedestruction of plastic materials.

DS

ME

N G

I N

E E

R I

N G

P

L A

S T

I C

S

3

Tribology: A Science in Motion

Table 1 Friction and wear energy dissipation.

4

Fatigue wear. When cyclical con-tact stresses on the polymer causethe deterioration of surface integrity,fatigue wear is encountered.Eventually, the compromised plasticsurface will slough and pit, resultingin material loss at the interface.

Corrosive wear. When materialsin motion react chemically with theirsurrounding environment and pro-gressively lose material, this is knownas corrosive wear. This form of wearis usually associated with metals andthe oxidation of their surfaces. Truecorrosive wear in polymers is notusually evident, however, chemicalresistance issues with specific plasticresins can contribute to the loss ofmaterial in sliding motion.

Friction

The natural resistance to the slidingmotion of one surface against anotheris known as friction. The successfulfunctioning of some applications arebased on the existence of a certainminimum amount of friction. Anexample of this would be the stop-ping of a vehicle through the frictionof the brake pads against the brakedisc or achieving forward motion viafrictional resistance of a shoe soleagainst the ground.

Most equipment design, however,requires a relatively low and consis-tent amount of frictional resistance toassure smooth functioning and actua-tion. Also, knowledge of the frictionalcharacteristics allows for a moreaccurate understanding of the actuat-ing forces necessary to determinemotor power.

Nylatron® internally lubricated thermoplasticgears provide improved wear and frictional resis-tance to the conjugateaction of mating teeth. These highly capable com-pounds also offer improvedresistance to repeated flexu-ral bending, a prime causeof gear tooth failure.

Originally undertaken as a

cost reduction, a metal

bicycle hub and bearing

assembly were redesigned

using several DSM

thermoplastic resins and

compounds. Using

advanced tribological

information to help create

this novel design, the OEM

not only achieved their

target cost-down, but also

increased life expectancy of

the assembly over 600%

compared to the original

metal parts.

DS

ME

N G

I N

E E

R I

N G

P

L A

S T

I C

S

5

Wear and Friction Measurement Techniques

Wear rates and coefficients of frictionare often used as the initial basis forthe materials selection process in plas-tics part design for dynamic applica-tions. There are numerous types of tribological test methods, primarily dictated by the nature of the materialsand by regional preferences. In NorthAmerica, the prevalent test standardfor the evaluation of rigid plastics isASTM D-3702: Wear Rate andCoefficient of Friction of Materials inSelf-Lubricated Rubbing Contact Usinga Thrust Washer Testing Machine. It is a constant contact, constant veloc-ity test in which a plastic specimen isrotated against a low carbon steelcounterface until an equilibrium amountof wear has been experienced. Aswith all standardized tests, D-3702does not purport to be indicative ofany individual application, but ratheris to be used as an initial guide in thematerial selection process.

Test procedure

An injection molded thermoplasticthrust washer is loaded to a constantpressure and then placed in rotational

motion against a stationary counter-face for a prescribed period of time.The mating surface is manufacturedfrom an AISI C-1018 steel with a hardness of Rc 20 ± 5 and a surfacefinish of 16 ± 2 µin. AA.

The standard allows for a matrix of 12 test PV (pressure x velocity) products, ranging from 1,250 to10,000 lbs/in2–ft/min at velocities of10, 50, and 250 ft/min. After a break-inperiod of 40 hours, the thrust washeris removed from the test apparatusand cleaned of all debris. After con-ditioning at room temperature for aperiod of at least one hour, the heightof the washer is measured to a preci-sion of 0.0001 inches in four places,each 90 degrees apart. Those valuesare then averaged.

The washer is again placed in dynamiccontact with the same mating surfaceand tested for an additional period oftime, sufficient to achieve an equilib-rium loss of material. The typical testduration during this phase is to bebetween 50 and 2,000 hours. Aftertesting, the specimen is cleaned ofdebris and allowed to come to room

temperature equilibrium. The washerheight is then measured at the samequadrants and those values are aver-aged. The net average loss in heightof the thrust washer is then recordedin inches.

Frictional resistance is monitored dur-ing the test by means of a load cellfixed to the stationary lower specimenholder and those torque values arerecorded in lb-in units.

More sophisticated wear machineversions incorporate the use of acomputer to control test functions, aswell as collecting real time data dur-ing each test. Test parameters suchas thrust washer loss in height, coeffi-cient of friction, interfacial tempera-ture and sound generation can bemonitored as a function of elapsedtime in order to more closely assesstribological responses.

DSM’s tribological test facility in Evansville, Indiana utilizesleading-edge analytical equipment, such as this dual headLewis Research LRI-1A Automated Tribometer which providesunparalleled information about the wear and frictional responsesof polymers in sliding motion. This fully automated, PC con-trolled thrust washer wear tester is capable of duplicating various sliding modes, velocities, pressures, and chemicaland thermal environments while monitoring real time propertychanges and responses versus time. This sophisticated analytical tool can detect material wear losses as small as0.00001 inch, collect 250 frictional data points within 3.5 sec-onds, continually measure interfacial frictional temperatures,and record frictionally generated noise at 35 frequencies withinthe audible spectrum.

6

Test data and significance

Wear rate. The equilibrium loss ofmaterial per unit time is known as thewear rate. According to the ASTM stan-dard, it is the loss in linear height of thethrust washer divided by the elapsedtime of the wear test. The value isexpressed in in/hr x 10-6 .

WR = (Xa) _ (Xb)

Twhere:

WR = wear rate (in/hr)Xa = average thrust washer lip

thickness (inches) after the break-in period

Xb = average thrust washer lip thickness (inches) after at least 50 hours of additional testing

T = test duration (hours)

Wear rates for plastic materials rangefrom 1 to 10 in/hr x 10-6 for highlywear resistant materials at lower PVconditions to over 2,000 in/hr x 10-6

for unmodified amorphous thermo-plastics, such as ABS. For manyapplications, wear rates of less than100-200 may be an indicator ofacceptable wear performance.

To put the wear rate numbers intoperspective, we need to relate theequilibrium loss of material to anapplication. For example, a materialwith a wear rate of 500 x 10-6 in/hrindicates the thrust washer is losing0.0005 inch during each hour of oper-ation. Assuming an operational life of500 hours, the total linear loss ofmaterial could be 0.25 inch. Foralmost every application this magni-tude of material loss probably wouldnot be acceptable. In contrast, if a

material exhibited a wear rate of 10 x10-6 in/hr, the overall material loss in500 hours would be 0.005 inch, amuch more reasonable value.

Most plastic materials wearing againsta harder surface, such as steel, exhibita higher initial wear rate, known asbreak-in wear. This typically occursas the softer material (in this case theplastic) transfers itself to the steelcounterface. Under most conditions,at a discrete point, this high rate ofmaterial transfer reduces to a muchslower rate, known as the equilibriumwear rate. Figure 1 details the wearloss of material as a function ofelapsed time. These real time dataare acquired through the use of aninstrumented wear tester and graphi-cally show the two significantly differentrates of wear.

Wear (K) factor. Data availablefrom many plastic resin suppliers is inthe form of a wear (K) factor, which isa proportionality constant equatingwear rate and the PV product.

WR = KPVwhere:

WR = wear rate (in/hr)K = proportionality constantP = test pressure (lbs/in2)

V = test velocity (ft/min)

Solving for K:K = WR/PV

The resulting value is expressed as awhole number, x 10-10, with units ofin3-min/lb-ft-hr.

The use of the wear (K) factor assumesthat the wear rate of plastics is propor-tional to the operating PV. This relation-ship, for most plastic resins and com-pounds, is valid within a very smallrange of PVs, if it exists at all. Thewear rate and frictional characteristicsof all plastics are highly dependentupon the specific PV. The fact that aplastic material will exhibit a proportionalwear rate at higher or lower PV points,unless actually tested, cannot beassumed. When evaluating materialsusing wear data, the test PV must beidentical as well as compliant with thesame standardized procedures.

Figure 1 Thrust washer wear test loss in specimen height versus time: Plaslube® AC-80/TF/20 (acetal copolymer with 20% PTFE) at 120 lbs/in2 x 100 ft/min.

Coefficients of friction (Cƒ).Plastic wear in a given application istypically a "go-no go" proposition:either the material wears an accept-able amount over the operational life ofthe part - or it doesn’t. Friction, theresistance to motion experienced bymating surfaces, is a much more sub-tle design parameter. Dynamic coeffi-cient of friction values are obtainedfrom torque measurements duringequilibrium and are calculated as:

ƒ = T/rW

where:ƒ = coefficient of friction

T = specimen torque (lb/in)r = mean test specimen radius

(0.531 in) W= normal force (lbs)

The coefficient of friction is the unit-less ratio of the force necessary toinitiate or maintain motion to the nor-

mal force pressing the surfacestogether. The force needed to initiatemotion from rest is the static value; theforce needed to maintain motion is thedynamic value. Two surfaces exhibit-ing a dynamic coefficient of frictionvalue of 0.50, therefore, would requiretwice the actuating force of a similarpair with a frictional coefficient of 0.25.

Torque measurements are continuallymonitored during the thrust washerwear test through the use of a loadcell attached to the stationary lowersample holder. At the successfulconclusion of an evaluation, thesedata are expressed as a RMS value.

In many cases, the evolution of fric-tional characteristics begin with thematerial transfer process. During this initial phase ever increasing frictionalvalues may be experienced until apeak value is reached.

After this peak, the frictional resistancewill decline until a consistent coefficientof friction level is achieved. Many problems can occur during the break-inperiod including stick-slip, chatter,motor stall and noise generation.

Figure 2 shows the frictionalresponse versus time of an unmodi-fied nylon 66 sliding against low car-bon steel at a velocity of 100 ft/min,under a load of 50 lbs/in2. While theequilibrium dynamic coefficient offriction averages 0.57, the break infriction peaked at a value that wasalmost twice as high - 1.11.

DS

ME

N G

I N

E E

R I

N G

P

L A

S T

I C

S

7

Figure 2 Dynamic coefficient of friction versus time: nylon 66 against C-1018 steel at100 ft/min and 50 lbs/in2.

8

Multiple point test data

Wear rates. This tribological valueprovides a good relational number incomparing several materials for initialconsideration. As an example, let’srelate the performance of an unmodi-fied PA46 with acetal. Both materialsare known for their excellent tribologicalcharacteristics. The equilibrium wearrates of these two materials, at a testpressure of 20 lbs/in2 and velocity of100 ft/min are shown in Table 2.

At this test PV of 2,000, acetal exhibitsabout 15% better resistance to wearthan does PA46. Other design con-siderations aside, acetal would bethe material of choice in a relativemotion application at an operationalPV similar to this test condition.

Without further information, an engi-neer would have to assume that acetalis still the polymer of choice for anapplication at another PV condition.

The wear resistance relationship of thetwo materials reverses dramatically,however, when tested at a higherpressure of 50 lbs/in2, but at the samevelocity of 100 ft/min (see Table 3).Under this increased load, the nylonpolymer exhibits approximately thesame rate of wear loss, while the wearrate of the acetal increases by almostan order of magnitude.

This dramatic change in the relativewear rates underscores the depen-dency upon operational conditionssuch as pressure and sliding velocity.

In order to determine the tribologicalcapabilities of a polymeric material overits useful range of PV values, at leastnine separate tests are conducted. Atypical capability grid covers pres-sures from 8 to 300 lbs/in2 and slidingvelocities between 40 and 250 ft/min.When viewed as a 3D graph, this tri-bological information yields a "perfor-mance envelope" which graphicallyportrays where a material is capableof supporting a dynamic load - andwhere it is not.

In addition to individual information ateach PV point, general trends can bemore easily assessed. For example,at some points within this performancegrid, PA46 exhibits essentially thesame resistance to wear at a givenvelocity as the load is increased (seeFigure 3). This phenomena is a gen-eral attribute of most nylon resins and isrelated to the effectiveness of materialfilm transfer mechanisms at specificminimum dynamic loads.

Table 2 Equilibrium wear rate comparing Stanyl® TW341 (PA46) to acetal copolymerat 20 lbs/in2 x 100 ft/min.

Table 3 Equilibrium wear rate comparing Stanyl® TW341 (PA46) to acetal copolymerat 50 lbs/in2 x 100 ft/min.

Figure 3 Wear rate performance envelope: Stanyl® TW341 (PA46).

Test Standard Units Stanyl® TW341 Acetal

Wear Rate ASTM D-3702 in/hr x 10-6 79 69

Test Standard Units Stanyl® TW341 Acetal

Wear Rate ASTM D-3702 in/hr x 10-6 89 652

DS

ME

N G

I N

E E

R I

N G

P

L A

S T

I C

S

9

In general, the PA46 wear rateincreases as load or velocities areraised. As important, a point atwhich this material is not capable ofsupporting dynamic load has beendetermined at 48 lbs/in2 and 250ft/min. Shown on wear grids aspoints using the legend “NotCapable”, these failures to supportdynamic load are determined by cri-teria like excessive wearing, sampledeformation, gross destruction of thepolymer or mating surface, or theinability to achieve an equilibrium inter-facial temperature. The knowledge ofwhere the performance edges of amaterial lie is important in the initialselection process.

Using this expanded tribologicalinformation the relative strengths andweaknesses between two materialsbecomes graphically evident. Thechart comparing the wear rates ofStanyl® TW341 (PA46) and acetal isdetailed in Figure 4. At several PVpoints both materials exhibit similarlygood resistance to sliding wear. Athigher velocities and PV test points,the acetal resin becomes incapableof successfully supporting dynamicloads and the nylon 46 becomes thematerial of choice for applicationsoperating at these PV conditions.

As with wear rate, frictional data pointsare also generated at various PV pointsand the information is placed in a 3Dgraph for evaluation. Figure 5 com-pares the frictional response of PA46 toacetal. From these data, one can easilysee the tribological "strong suit" ofacetals: low coefficients of friction con-sistent across all capable PV points.

In comparison, PA46, like allpolyamides, exhibits a broad rangeof frictional values, dependent uponPV test conditions. In some cases thePA46 values approach those foracetal, while at other points the coef-ficient is more than double.

In terms of low frictional performance,acetal would be the clear choice. Aswith the wear rate, however, there arePV points at which the material is notcapable of supporting dynamic load -hence, no frictional value is published.

Figure 4 Wear rate performance comparing Stanyl® TW341 (PA46) to acetal.

Figure 5 Dynamic coefficient of friction comparing Stanyl® TW341 (PA46) to acetal.

10

Noise generation. The presenceof frictionally induced noise in motionparts has become significant in allindustries, especially the automotive,business machine, and appliancemarkets. The integrity of an entireproduct is suspect by virtue of thesqueaking of a single internal part.Noise generation may be presentcontinually, only during the break-inperiod or transient in nature. Sincethe actual sound produced is highlydependent upon the configurationand materials used in the entireassembly, this again is not an inher-ent property of a plastic material.The potential for noise generation,however, may be identified early inthe design process using real timefriction and sound data.

In Figure 6 the sound pressure levelincrease correlates to the frictionalpeak in Figure 2. The doubling offrictional response during the break-in period, in this case, has causedthe noise generated from rubbingcontact to reach 109 dB. The eventualreturn to an equilibrium sound levelof 97 dB also correlates to the fric-tional equilibrium shown in Figure 2.

In addition to assessments of sound asfull sound pressure levels, the digitalacoustic sampling during the wear testallows for analyzing any sound frequencyrange. This capability is particularlyuseful in determining the origin ofunwanted noise.

Figure 7 details the frictionally gener-ated sound of a polymer versus itself, broken down into the component of 1/3octave frequencies which comprise thehuman audible spectrum (20 Hz to20K Hz). This chart graphically shows the extreme sound increase

localized around the 12K Hz frequency,which was found to be characteristicof the noise generated by this specificwear couple. This specific informationwould be useful in confirming the ori-gins of undesirable sound in anoperating system.

Figure 7 Frictionally generated sound pressure levels at 1/3 octave frequenciesversus time.

Figure 6 Frictionally generated sound pressure level versus time: nylon 66 against C-1018 steel at 100 ft/min and 50 lbs/in2.

Thermoplastics

The initial choice in selecting thermo-plastic resins for tribological applica-tions begins with the two major groupsof these melt-processible engineeringmaterials. Thermoplastics are classi-fied as either amorphous or semi-crys-talline, which is a primary determiningfactor in tribological, as well as physi-cal and mechanical properties.

Examples of amorphous plastics are polycarbonate, stryrenics, and severalhigh temperature resins. Semi-crys-talline resins include such materials aspolyamides (nylons), polyesters, poly-propylene, and acetal.

Compared to amorphous plastics,crystalline resins display intrinsicallygreater resistance to wear. Amorphousresins, in fact, do not possess any sig-nificant level of dynamic load-bearingcapability. They rely heavily on modifi-cation through the use of additives toserve in these types of applications.

Dynamic Mechanical Analysis(DMA). A common cause of tribolog-ical failure of thermoplastic parts isthe inability to support a given loaddue to the loss in modulus at friction-ally-induced elevated temperatures.An analytical test, dynamic mechani-cal analysis, or DMA, provides aninsight into the modulus characteris-tics of plastics as a function of tem-perature. Figure 8 compares thechange in modulus of several glassfiber reinforced, PTFE lubricated ther-moplastics against increasing temper-ature. Semi-crystalline resins such asPPS and PEEK display a high degreeof stiffness at points below their indi-vidual glass transition temperatures(Tg), a major thermal transition com-mon to all thermoplastics.

Once past these critical points, thecompounds rapidly lose a significantpercentage of their original stiffness.In contrast, nylon polymers (PA66 andPA46) display a much more gradualloss of modulus after these points.This is a primary factor in explainingthe superior dynamic load bearingcapabilities of polyamides.

Amorphous resins, such as polycar-bonates, are extremely stiff up to theirTg, after which they become essential-ly fluid. From a design point, amor-phous plastics should be used at tem-peratures (either ambient or frictionallyinduced) that are at least -1˚C (30˚F)below these critical transitions.

Crystalline thermoplastics

Crystalline resins tend to have higherstrength and rigidity than amorphousresins. Over a wider temperaturerange they have an inherent resis-tance to chemical attack and exhibit abroader processing window.

Polyamides. Polyamide (nylon)resins, such as DSM’s Akulon® family ofnylon 6 and nylon 66 materials, exhibitlow wear rates, as well as chemicalresistance to oils and greases. Theyalso retain a high degree of theseproperties at elevated temperatures.A relatively new family of high tempera-ture polyamides, Stanyl® PA 46, exhibitsome of the highest load bearing capa-bilities of any thermoplastic resins.

Overall, nylons possess an excellentengineering combination of tough-ness and high strength. Most nylonsare hygroscopic (water absorbing), aprocess which decreases modulus,improves toughness and may alsoaffect post-molding dimensions.

DS

ME

N G

I N

E E

R I

N G

P

L A

S T

I C

S

11

Thermoplastic Polymers

Figure 8 DMA modulus versus temperature comparing 30% glass fiber reinforced,15% PTFE lubricated thermoplastics.

12

Polyesters. Arnite® polyesterresins, both PBT and PET, are highlyresistant to solvents and to moisture.They are very rigid plastics and pos-sess good electrical properties. Whiledisplaying wear rates typically higherthan those of nylons, polyesters havea very uniform rate of material lossand frictional response.

Acetals (POM). Acetal resinsexhibit low coefficients of friction andgood wear resistance under certainPV conditions. Coupled with excellentresistance to dynamic fatigue and pos-sessing a high unreinforced modulus,this resin is a good choice for plasticgear applications. Acetal is not a highuse temperatures resin and is not suit-able for mechanical applications inexcess of 104˚C (220°F).

Amorphous thermoplastics

The polymer chains of amorphousthermoplastics are randomly orderedas compared to structured semi-crys-talline thermoplastics. They are lessresistant to absorption and diffusion ofcontaminants, thus making amorphousthermoplastics more susceptible tochemical attack. Resins with amor-phous character, however, show lessmold shrinkage and less post-molddimensional change. Amorphousmaterials are more isotropic, shrinkingsimilarly in all directions, which leads toless warpage in molded parts as com-pared to crystalline resins. Thesematerials are used in dimensionallycritical applications, such as businessmachine parts.

Polycarbonates (PC).Polycarbonates, such as DSM’sXantar® resins, display a good balanceof rigidity and stiffness at elevatedtemperatures, excellent electricalproperties and good impact strength.

In order to be used in most dynamicapplications, such as bushings orgears, polycarbonate must be eitherreinforced or internally lubricated toprovide adequate wear resistance.PC compounds are used extensivelyin business machine applications thatrequire dimensional accuracy andhigh strength.

Styrenics. Styrenics are lowercost resins and are available in avariety of forms: higher impactstrength ABS and higher heat SANas compared to low-end polystyrene(PS). Again, in terms of wear appli-cations, all styrenics must either bereinforced or internally lubricated.

Gears

Injection molded gears are used in applica-tions ranging from motion translation incopiers and printers to transmitting torque inthe horsepower range. The ability to be usedunlubricated, the reduction or elimination ofrunning noise, and the high productivity/lowcost potentials of plastics gearing are someof the reasons for the high growth seen inthis area. DSM produces a broad portfolio ofthermoplastic resins and compounds thatcan provide the correct balance of these crit-ical properties, meeting the most demandingperformance criteria in a cost-effective form.

Internal lubrication

The most effective method of reduc-ing wear rates and frictional charac-teristics of thermoplastic resins isthrough the process of internal lubri-cation. As a logical extension ofexternal lubrication, this involves theincorporation of either solid or liquidlubricants into the polymer matrix dur-ing the melt extrusion compoundingoperation. As a finished part, thesethermoplastics offer a high degree ofsurface lubricity that is presentthroughout the life of the unit. Inmany cases, internal lubricants elimi-nate the need for ongoing externallubrications, dramatically reducingmaintenance and improving reliability.

Polytetrafluoroethylene(PTFE)

The most common thermoplastic internallubricant is another thermoplastic resin -polytetrafluoroethylene, or PTFE. Bestknown as the non-stick coating onfood cooking surfaces, this solidexhibits the lowest known coefficientsof dry sliding friction. The discreteparticles of PTFE that are suspendedin the thermoplastic matrix easilyshear from the plastic interface andtransfer to the mating surface. Whena sufficient amount of lubricant hasformed a surface film on the matingsurface, friction, wear, and noisebecome dramatically reduced.

The significant tribological value ofincorporating PTFE into a thermoplas-tic matrix can be seen in Figure 9.Plaslube® NY-1/TF/15 (nylon 66 +15% PTFE) was evaluated for dynamiccoefficient of friction values com-pared to the unmodified nylon 66tested in Figure 2. Under identicaltest conditions the equilibrium fric-tional value is almost 1/3 of that forthe unmodified resin.

In addition, the break-in peak becomesinsignificant and the stability of thefrictional response throughout the testis remarkably stable. The optimalamount of PTFE additive for a givenresin is dependent upon the require-ments of an individual application, butweight loadings between 15 and 20%typically yield optimal results.Increasing amounts of PTFE usuallyproduce lower friction and wear ratevalues for the polymer.

DS

ME

N G

I N

E E

R I

N G

P

L A

S T

I C

S

13

Lubricants

Figure 9 Dynamic coefficient of friction comparing nylon 66 to Plaslube® NY-1/TF/15(nylon 66 with 15% PTFE) at 100 ft/min and 50 lbs/in2.

Figure 10 shows the frictionalimprovement due to the addition ofPTFE in Stanyl® PA46. This compara-tive performance envelope shows thatStanyl® TW371 displays a consistentlylower frictional character across awide matrix of PV test points, whencompared to the unmodified material,Stanyl® TW341. The PTFE internallubricant also provides dynamic loadbearing ability to the nylon 46 resin atPV points that were originally inca-pable of such performance.

Due to the effective reduction of inter-facial friction and generated heat,PTFE also substantially reduces wearrate, as seen in Figure 11. At someconditions, the rate of wear is reducedtenfold. At other PVs, where Stanylwas previously unable to supportdynamic load, the wear rate is similarlylow. The additive PTFE significantlyimproves an already capable tribo-logical material.

Polymethyldisiloxanes

Polymethyldisiloxanes, commonlyreferred to as silicones, are highmolecular weight, viscous polymersthat are used in thermoplastics toreduce “break in” frictional peaks.Under some tribological conditions, silicones maintain reasonable frictionallevels until the polymer’s transfermechanism to their mating surfaces isaccomplished. In this regard, internalsilicone lubricants impart an actionsimilar to externally applied greasesduring assembly procedures.

Silicone modified thermoplastics aremanufactured by DSM using propri-etary compounding techniques.Silicones are true boundary lubricants,having the ability to readily absorbonto the mating surfaces.

Only a few molecular layers arerequired to dramatically change inter-facial behavior. Low loading levels ofsilicone are, therefore, very effective.During operation, the silicone boundarylayer is replenished by new siliconefrom within the polymer matrix.

This is possible because of the sili-cone’s slight incompatibility with thethermoplastic, resulting in exclusionand eventual migration to the matrixsurface through normal diffusion processes. Silicones, however, canalso trap abrasive particles at thewear interface, leading eventually tocatastrophic failures. While it is veryhard to predict these occurrences, the presence or potential presence of abrasive third body particles, suchas sand or glass fiber debris, mightcontraindicate the use of internal silicone fluids.

14

Figure 11 Wear rate performance comparing Stanyl® TW341 (PA46) to Stanyl® TW371(PA46 with 15% PTFE).

Figure 10 Dynamic coefficient of friction comparing Stanyl® TW341 (PA46) to Stanyl®

TW371 (PA46 with 15% PTFE).

PTFE and Silicone

Using a combination of PTFE and silicone as internal lubricants canresult in a synergistic improvement ofwear and friction properties. Formationof a complete silicone boundary layeris faster than the transfer and formationof a PTFE solid boundary layer.

Binary lubricant packages

Binary lubricant packages are combi-nation of solid lubricants that performsynergistically in enhancing tribologicalproperties. Compared to traditionalPTFE internal lubrication, these binarypackages also offer increased loadbearing capabilities, improved tough-ness, and fatigue endurance. Whileslightly less effective in reducing wearrates and frictional response, the binarypackages offer a reduced cost to volume ratio - on the order of 10-20%.

The wear rate performance graph inFigure 12 shows the relative advan-tages and disadvantages of binary lubricant packages compared to PTFElubricants. Stanyl® TW371, a 15%PTFE lubricated nylon 46, displays theuniformly low wear rates associatedwith this type of tribological aid.Stanyl® TE373, which contains

a binary lubricant package, allows thePA46 resin to support dynamic loadsat several high PV points at whichPTFE was ineffective. The TW371exhibits wear rates consistently lowerthan those of TE373, however, it shouldbe noted that both compounds areremarkably wear resistant.

DS

ME

N G

I N

E E

R I

N G

P

L A

S T

I C

S

15

Bushings

Used as a boundary between moving parts, bush-ings have been made from materials ranging fromleather to metal alloys. Thermoplastics and theircompounds now provide the greatest range of unlu-bricated wear and friction reduction performance inbushing applications at the most cost-effective, highproductivity rate available from modern materials.Ranging from nylon 66 to sophisticated carbon fiberreinforced, internally lubricated high temperaturecompounds, industrial bushings are used in all mar-kets from appliances and sporting goods to aeronau-tics and sophisticated medical diagnostic equipment.

Figure 12 Wear rate performance comparing Stanyl® TE373 (PA46 with binarylubricant package) to Stanyl® TW371 (PA46 with PTFE).

16

Molybdenum Disulfide (moly)

DSM pioneered the use of molybde-num disulfide as the first internal lubri-cant used in a thermoplastic. Nylatron®

lubricated thermoplastics remain thebest known and most widely used inthis class. A geologically minedmaterial, MoS2, is incorporated intonylon resins in amounts less than 2%by weight. This very finely dividedpowder acts as a nucleating agent innylon resins, resulting is a highly crys-talline surface "skin". This morphological

attribute causes a Nylatron part toexhibit improved surface hardness and,as a result, better tribological behavior.

The improvements to both wear ratesand load bearing capacity of nylon 66by the use of moly can be seen inFigure 13. Nylatron GS-HS wear ratesat lower and middle PV ranges areremarkably reduced, while other higherPV points become capable of supportingdynamic loads.

Moly is not as effective as PTFE inreducing wear and friction, however,the use of moly does not reduce thetoughness of nylons in the manner ofPTFE. It also provides for more costeffective materials than PTFE lubricatedcompounds. Flexural fatigueendurance characteristics are signifi-cantly improved over PTFE lubricants,making gear applications a natural forthese materials.

Figure 13 Wear rate performance comparing Nylatron® GS-HS (nylon 66 withmolybdenum disulfide) to nylon 66.

DS

ME

N G

I N

E E

R I

N G

P

L A

S T

I C

S

17

Glass fiber

Glass fiber may be added to resins inorder to improve short-term mechanicalproperties and thermal performanceproperties - strength, stiffness, hard-ness, and heat deflection. These cost- effective reinforcing agents alsoimprove the long term property of creepresistance. In general, reinforcement ofthe bulk leads to slower wear rates andhigher PV limits.

Glass fibers at the surface may increasethe wear of the counter-surface and,perhaps, increase the coefficients offriction, depending on the materials.PTFE, or a combination of PTFE/sili-cone, may be added as a lubricant inorder to minimize these effects.Additionally, molding with the meltflow parallel to the wear surfaceresults in fewer exposed glass fiberends and hence, less wear of thepolymer counterface.

One of the most significant detrimentaleffects of glass fiber reinforcement inthermoplastic wear is the abrasive-ness to mating counterfaces. Thesereinforced thermoplastics can causesignificant damage to all but thehardest metals.

Figure 14 compares the metal matingsurface abrasion of two nylon 66 com-pounds: Plaslube® J-1/30/TF/15 (30%glass fiber reinforced / 15% PTFE lubri-cated) and Plaslube® NY-1/TF/15 (unre-inforced /15% PTFE). At all PV levelstested, the addition of glass fiberextensively abraded the soft steelcounterface and this effect increasedwith added load. Since relative motionrequires two surfaces to be in movingcontact, the wear of both sides mustbe taken into account when assessingoverall tribological capability.

Carbon fiber

Engineering thermoplastics reinforcedwith carbon fibers are high perfor-mance materials. Such compoundsexhibit the highest combination ofstrength, modulus, short-term heatresistance, and creep resistance for anyfiber reinforcement. They are also bothelectrically and thermally conductive.In addition to causing plastic parts tobecome electrostatically dissipative,the carbon fiber aids in the thermalconductivity of frictionally generatedheat from the wear interface.

The abrasive effect carbon fiber has onmating surfaces is significantly lessthan that of glass fiber. While slightlymore abrasive than unreinforced resins,the relatively low abrasion of carbonfibers is one of the primary reasons forthe use of these composites in tribolog-ical applications. Carbon fiber rein-forced compounds, internally lubricat-ed with PTFE, are among the mostcapable thermoplastic compoundswhen considering the combination ofmechanical and tribological properties.

Reinforcements

Figure 14 C-1018 steel mating surface abrasion comparing Plaslube® J-1/30/TF/15(nylon 66 with glass fiber and PTFE) to Plaslube® NY-1/TF/15 (nylon 66 with PTFE).

18

The vast majority of thermoplasticwear and frictional data generatedhave been against the low carbonsteel counterface dictated in ASTM D-3702. Specifying a common matingsurface in these tests provides for con-sistent and reproducible tribologicaldata that is well suited for initial com-parisons. Since C-1018 steel is not acommonly used dynamic plasticmate, questions about the tribologicalcapability against other materials are

very valid. The use of very hard met-als or even softer ones will almostcertainly affect wear and frictionaldata results of plastic materials.

Plastics in motion against other plas-tics is a very common design situation.The possible matrix of thermoplasticsand their compounds against otherthermoplastics is prohibitively large toallow for comprehensive testing.Using similar materials together in an

unlubricated dynamic motion appli-cation is well recognized as anavoidable wear couple. Contrary tobelief, identical polymeric materialsare successfully used as mating sur-faces in many applications. As withall wear applications, knowing theoperational limitations of the materialsunder consideration is a key successfactor. Figure 15 summarizes aseries of plastic on plastic wearrates. Stanyl® PA46 and acetal weretested as unmodified and also asPTFE lubricated materials againstthemselves and each other. All testswere conducted at a velocity of 40 ft/min and the wear rates devel-oped at various loads are plottedtogether on a semi-logarithmic scale.A wear rate of 200 x 10-6 in/hr waschosen as an arbitrary acceptablelimit to determine maximum dynamicload on the wear couple at this velocity.Acetal against itself supported only 11 lbs/in2, while the nylon 46 couplewas capable of up to 68 lbs/in2, anincrease that is six-fold. AddingPTFE dramatically improved wearperformance of both materials. Themating of nylon 46 against an acetalcounterface yielded a load bearingability that was 30% better than theacetals with PTFE and only slightlyless than the nylon 46 compounds withPTFE. By utilizing these dissimilar,unmodified resins as mates, wearresistance approximates the level ofthe more expensive PTFE modifiedcouples. Figure 16 summarizes thedynamic frictional responses of thesetests. Again, the use of unmodifiedPA46 against the unmodified acetalyielded frictional values that were significantly lower than those for thePTFE modified resins.

Figure 15 Plastic-on-plastic wear rate comparison of various thermoplastics andcompounds at a sliding velocity of 40 ft/min.

Plastic on Plastic Wear

Figure 16 Plastic-on-plastic dynamic coefficient of friction comparison of variousthermoplastics and compounds at a sliding velocity of 40 ft/min.

DS

ME

N G

I N

E E

R I

N G

P

L A

S T

I C

S

19

It cannot be overemphasized thatstandardized wear and frictional testvalues may not be used as actualdesign parameters. They are intendedto provide the designer with an initialpoint of reference in evaluating poten-tial candidates for relative motionapplications. Rather than relying ontribological data developed at a sin-gle PV point for the initial selectionprocess, the use of multiple point testdata, arranged in comparative 3Dgraphs, yields an unprecedentedlevel of engineering sophistication. In this example we will consider therelative capabilities of two thermo-plastic bearing materials:

- Stanyl® TW271F6 (PA46 +

30% glass fiber + PTFE)

- PPS + 30% glass fiber +

15% PTFE.

Both materials exhibit high temperatureresistance, excellent wear resistanceand a high degree of mechanicalstrength. Viewing the information inFigure 17, the wear resistance of bothcompounds is excellent and compara-ble at all velocities within the 2,000 PVlevel. Based on this characteristic,either would be a good materialchoice. Performance similaritiesdigress as the test load is increased. At the moderate velocity of 40 ft/minand a dynamic load of 300 lbs/in2, thePPS-based compound is clearly unac-ceptable in terms of wear resistance,while the PA46-based analog contin-ues to exhibit a very capable level ofperformance. It is at these points thatthe relative differences in materialsbecome apparent.

Figure 18 shows the frictionalresponses for these two compounds.While reasonably similar, the PA46material consistently yields lower

dynamic frictional values, surely aprimary reason for the improved rela-tive wear resistance.

Using Tribological Data for Material Selection

Figure 17 Wear rate performance comparison of Stanyl® TW271F6 (PA46 with glassand PTFE) to PPS with glass and PTFE.

Figure 18 Dynamic coefficient of friction comparison of Stanyl® TW271F6 (PA46 withglass and PTFE) to PPS with glass and PTFE.

While all glass fiber reinforced thermo-plastics are abrasive to many matingcounterfaces, Figure 19 details thesedifferences. As with the comparativewear rates of the plastics, the PPScompound uniformly exhibits a higherdegree of abrasiveness to the mildsteel counterface. This is no doubtdue to the more rigid and brittlenature of PPS compared to nylon 46and the stiffness in which the glassfibers are held in the polymer matrix.

A major reason for the superior wearand frictional attributes of nylon 46as a tribological polymer and com-pound compared to PPS can bereadily seen in Figure 20. A com-parison of modulus versus tempera-ture characteristics shows the PPScompound to exhibit approximately20% higher modulus than the nylon46 from far sub-ambient, up to justbeyond the PPS glass transition tem-perature, about 90˚C (194˚F). Atabout 116˚C (241˚F), the decliningmodulus of the PPS crosses thePA46 value. From this point untilboth approach their respective crys-talline melt points [288˚C (550˚F) forPPS, 295˚C (563˚F) for nylon 46], theStanyl® compound exhibits about60% greater modulus. This dramaticimprovement in being able to supporthigher loads at these temperaturesexplains the superior tribologicalcharacter of Stanyl® PA46 resins andcompounds.

20

Figure 19 Mating surface abrasion comparison of Stanyl® TW271F6 (PA46 with glassand PTFE) to PPS with glass and PTFE.

Figure 20 DMA comparison of modulus versus temperature of Stanyl® TW271F6 (PA46with 30% glass and PTFE) to PPS with 30% glass and 15% PTFE.

DS

ME

N G

I N

E E

R I

N G

P

L A

S T

I C

S

21

In addition to resins, internal lubri-cants and reinforcements, the multi-tude of operating conditions to whicha plastic part is subjected helps todetermine tribological capability.Some of these conditions can bealtered in a given design to enhanceperformance; some cannot.

It is still of primary importance to rec-ognize the effect these criticalparameters may have on the tribolog-ical capabilities of plastics, especiallyin the initial phases of the design pro-cess. Some of the most importantapplication conditions that affectwear and friction of plastic parts are

shown in Table 4. If a majority ofthese application parameters can bedetermined, and optimized to someextent, the chances of success of agiven thermoplastic or compound in atribological design may be increased.

Key Tribological Application Parameters

Table 4 Application conditions that affect wear and friction of plastic parts.

Parameter Considerations

Velocity Surface speed, Acceleration

Load Amount, Constant, Intermittent, Shock, Sinusoidal

Duty Cycle How Long "On", How Long "Off"

Motion Unidirectional, Reciprocal, Oscillatory, Sliding, Rolling, Radial, Axial

Mating Surface Type, Hardness, Surface Finish, Stationary or Dynamic

Ambient Temperature Constant, Min-Max, Unusual Peaks

External Lubrication None, Initial, Continual, Filtered/Non-Filtered

Environment Dusty, Aqueous, Chemical

Fabrication Degraded, Crystallinity, Fiber Orientation

Business Machines

DSM supplies a vast array of thermoplasticsused in the many relative motion parts found intoday’s printers and copiers. These applicationsdemand rigidity, dimensional stability, strength,impact resistance and electrostatic dissipation –while also providing low and consistent frictionand wear. The elimination of frictional noise,improved durability and simplified assemblyhave been the primary drivers for theseadvanced information technology applications.

22

Typical PV Situations and Material Selection

High P, HIgh V

Tribological • Load-induced increase in real contactResult area, severe frictional responses, rapid

and unmitigated interfacial temperature increases.

General Material • High temperature resistant resins, use ofRecommendations reinforcements to increase modulus, high

conductivity fiber reinforcements (carbon fiber), optimal PTFE internal lubrication.

DSM Product • Stanyl® TW271F6Recommendations • Electrafil® J-1/CF/30/TF/15, J-50/CF/30/TF/15

Applications • High PV bushings, bearings, thrust washers, cams and high torque, high pitch line velocity gears

High P, Low V

Tribological • Bulk material properties predominate,Result need for higher modulus and/or internal

lubrication.

General Material • Fiber reinforcement is recommended to Recommendations increase modulus and hardness. Need

for internal lubrication (with and without reinforcement) may be needed.

DSM Product • Stanyl® TW200F6, TW271F6, TE373Recommendations • Akulon® J-1/30, J-3/30

• Fiberfil® J-50/30• Nylatron® GS-51• Plaslube® J-1/30/TF/15, J-50/30/TF/15

Applications • High pressure bearings, bushings, cams and slides, higher torque gears

Wear involves a number of processes,all of which may be influenced by oper-ating conditions: temperature, load,velocity, contact area, duration, environ-ment, bulk material properties, surfacefinishes, and vibration. Wear effects can

be minimized by modification of the ther-moplastic with additives, fillers, or rein-forcements. Table 5 below describesdifferent effects of varying pressure andvelocity combinations experienced inbearing or gear related applications.

It should be used as a general guide toassist in the selection of the resin/rein-forcement/lubrication combination foryour component. The PV ranges usedare not absolute and represent relativePV ranges typically experienced.

Low P, Low V

Tribological • Bulk stresses are low, heat generated at

Result interface is easily dissipated.

General Material • Unmodified semi-crystalline thermo-

Recommendations plastics, MoS2 lubricated nylons.

DSM Product • Stanyl® TW341

Recommendations • Nylatron® GS-HS

• Akulon® F223D

Applications • Low torque, low velocity gears

• Low PV bushings, bearings and slides

Pressure

Slidin

g V

elo

cit

y

Low High

Hig

hLow

Low P, High V

Tribological • Interfacial effects predominate, creep

Result and modulus are typically not factors.

General Material • Unreinforced semi-crystalline or

Recommendations amorphous resins, internally lubricated.

DSM Product • Stanyl® TW371

Recommendations • Plaslube® NY-1/TF/15, PC-50/TF/15,

AC-80/TF/20

Applications • Thrust collars and washers

• High velocity seals, bushings, bearings

Table 5 Typical PV situations and material selection.

DS

ME

N G

I N

E E

R I

N G

P

L A

S T

I C

S

23

Product Material Description

Akulon® F-223D Nylon 6, Medium Viscosity

Akulon® J-1/30 Nylon 66, 33% Glass Fiber Reinforced

Akulon® J-3/30 Nylon 6, 33% Glass Fiber Reinforced

Akulon® S-223D Nylon 66, Medium Viscosity

Arnite® TO6 202 PBT, Medium Viscosity

Arnite® TV4 261 PBT, 30% Glass Fiber Reinforced

Electrafil® J-1/CF/30/TF/15 Nylon 66, 30% Carbon Fiber, 15% PTFE

Electrafil® J-1/CF/30/TF/13/SI/2 Nylon 66, 30% Carbon Fiber, 13% PTFE, 2% Silicone

Electrafil® J-50/CF/30/TF/15 Polycarbonate, 30% Carbon Fiber, 15% PTFE

Fiberfil® J-50/30 Polycarbonate, 30% Glass Fiber Reinforced

Nylatron® GS-HS Nylon 66, Molybdenum Disulfide, Heat Stabilized

Nylatron® GS-51 Nylon 66, 30% Glass Fiber Reinforced, Molybdenum Disulfide

Plaslube® AC-80/TF/20 Acetal, 20% PTFE

Plaslube® J-1850/30/TF/15 PBT, 30% Glass Fiber Reinforced, 15% PTFE

Plaslube® J-1/30/TF/15 Nylon 66, 30% Glass Fiber Reinforced, 15% PTFE

Plaslube® J-1/30/TF/13/SI/2 Nylon 66, 30% Glass Fiber Reinforced, 13% PTFE, 2% Silicone

Plaslube® J-50/30/TF/15 Polycarbonate, 30% Glass Fiber Reinforced, 15% PTFE

Plaslube® J-50/30/TF/13/SI/2 Polycarbonate, 30% Glass Fiber Reinforced, 13% PTFE, 2% Silicone

Plaslube® NY-1/TF/15 Nylon 66, 15% PTFE

Plaslube® PC-50/TF/15 Polycarbonate, 15% PTFE

Stanyl® TW341 PA46, Medium Viscosity

Stanyl® TW200F6 PA46, 30% Glass Fiber Reinforced

Stanyl® TE373 PA46, Binary Lubricant

Stanyl® TW371 PA46, 15% PTFE

Stanyl® TW271F6 PA46, 30% Glass Fiber Reinforced, 15% PTFE

Table 6 DSM materials for tribological applications.

Key DSM Tribological Grades

Tribological data library. Thematerials in Table 6 are the key DSMgrades for tribological applications.DSM has completed full tribological

performance grid evaluations of ourprimary thermoplastic resins andcompounds used for relative motionapplications.

For more information please contactyour local DSM sales representative.