Branching andcontrol manualwith DuPontEngineeringPolymers

®

DuPont Engineering Polymers

® DuPont registered trademark

2

CONTENTS

Synergy at work 3

DuPont Engineering Polymers in the branching and control industry 4

Outstanding performance 5-8

Research and development 9

Applications

• Protection 10-11

• Control 12-14

• Wiring devices 15-17

• Secondary protection 18

Technical resources for effective cost reduction 19

Thermoplastics versus thermosets: a cost comparison for Branching and Control devices 20

Summary 22

It all started with simple insulatorsmade of wood, marble, slate andceramics.

Then came thermoset polymers,which could be transformed frompalette or other forms into intricateshapes while retaining the requiredthermal and electrical propertiesand which are still used, to a certain extent, today.

More recently, engineering thermo-plastics, with their excellent elec-trical and thermal properties havebeen adopted by the Branchingand Control industry.

The design and processing possi-bilities inherent in thermoplasticshas led to added component andintegration functionality - forexample, in assemblies usingsnap-fit or welding technologies.This has, in turn, led to productminiaturisation and cost reduction.

An outstanding feature of thermo-plastics is that they can be remeltedand re-used.

Today’s broad thermoplastic product offering enables electricalengineers to reduce energy, costand weight, driving the evolutiontowards new-generation Branchingand Control components.

Synergy at work

3

4

Electricity is a part of our lives.People use it for heat, light, theactivation of household appliances,transportation and communication- to name just a few examples.

But electricity has certain inherentrisks - and it is therefore essentialthat strict controls are applied toguarantee safety in its daily use.

Branching & Control (B&C) iscomprised of devices that:- guarantee the safe use of

electricity (protection)- help control electricity (control)- establish connections

(wiring devices)- include all the above-mentioned

functions (such as secondaryprotection and enclosures)

In this brochure, we will focus onthe use of DuPont EngineeringPolymers such as Crastin® PBT andRynite® PET thermoplastic polyesterresins, Delrin® acetal resins, Hytrel®

thermoplastic polyester elastomers,Minlon® mineral reinforced nylonresins, Vespel® polyimide parts,Zenite® LCP liquid crystal polymersand Zytel® nylon resins.

These products are complementedwith a range of well known products such as Mylar® polyesterfilm, Kapton®polyimide film,Nomex® brand thermal technologyand Teflon® fluoropolymer resin.

All these DuPont products haveopened new opportunities forelectrical engineers in the areas ofcost reduction, miniaturisationand higher efficiencies.

DuPont’s Engineering Polymerrange was developed to serve the

B&C industry’s most demandingrequirements and has helped engineers throughout the industryto optimize quality, performance,and productivity.

DuPont has also established fundamental data regarding theenvironmental and recyclingproperties of various materials toback up existing procedures andfacilitate future industry, customerand end-user requirements.

With regard to specific regulationsconcerning flame retardant (FR)products, it should be noted that,globally, DuPont does not manu-facture any materials containingPolybromiated Biphenyls (PBBs)or Polybromiated Diphenylethers(PBDEs). Likewise, DuPontEngineering Polymers has ledthe way in eliminating heavymetal colouring systems such ascadmium and chromium.

In addition, DuPont is drivingactivities to offer non-halogen,non-red phosphorous-containingflame retardant resins to theBranching & Control industry byusing a variety of FR packagessuch as:- standard halogen and phospho-

rous-free flame retardants- unique and patented FR

packages- inherently flame retardant

polymers or blends - for example those containingLiquid Crystal Polymers

DuPont Engineering Polymers in theBranching and Control industry

Fig. 1. DuPont product portfolio for the B&C market

Crastin® PBT

Delrin® acetal

Zytel® HTNHigh TemperatureNylon

Zytel® nylon

Zenite® LCPLiquid CrystalPolymer

Rynite® PET

Hytrel® TEEE

Non FR

extrusiontoughenedreinforcedunreinforced

FR

extrusiontoughenedreinforcedunreinforced

FR = flame retardent

5

The basic function of Branching& Control equipment is to connectand interrupt electrical circuitssafely over the life cycle of adevice.

This can sometimes be complex,as in automatic circuit interrup-tions in the case of overload orleakage (e.g. MCBs, RCCBs orfuses) and controlled interruptions(e.g. plugs, switches, connectors,contactors or relays).

During the service life of a circuit,various electrical phenomena mayoccur which can adversely affectinsulating properties. Consequently,electrical engineers need to selectthe best materials to manage theseeffects.

Some factors affecting the engineer’s choice of insulatingmaterials include:- overheat resulting from current

overload or poor contact resis-tivity

- the formation of an electricalarc resulting in sudden tempera-ture increase, the generation ofpressure wave, and an erosionor chemical decomposition inthe insulating material

- surface contamination from theoutside environment causingtracking between the activeparts

- ignition of the insulator- the insulation of contacts due to

outgassing of organic materialsin the immediate surroundingof the device

For optimal performance underconditions like these, insulatingmaterials need to possess the fol-lowing characteristics:

Flammability - self extinguishing

Electrical- good dielectric strength - sufficient volume and surface- resistivity adequate arc andtracking resistance

Thermal - heat resistance (both short and longer term)

Mechanical- stiffness, toughness and impactresistance

Chemical- chemical and weather

resistance to aggressive environments

Dimensional- warpage, coefficient of thermal

expansion, moisture pick-up

The electrical industry has devel-oped specific standards to mini-mize or eliminate risk when usinginsulating materials.

DuPont ThermoplasticEngineering Polymers enableelectrical engineers to meet awide variety of these standards.

It’s often a case of combiningsmart design with the right product. This brochure aims tohelp design engineers to find theright mix of products, designtechniques and innovative ideasfor cost effective solutions tonew applications.

Outstanding performance

Standard B&C industry testmethodsBesides the high standards of mechanical, chemical and dimensional stability of DuPontEngineering Polymers, a group ofspecific electrical design require-ments is herewith described indetail, including:- flammability- long term temperature ageing- short term temperature perfor-

mance- insulation properties including

CTI

FlammabilityThe burning and damping behav-iour of an insulator is related notonly to resin formulation but alsoto the shape of the applicationsurface. For an overall comparison,and to aid selection by the engineer,two different test methods will bedescribed in more detail. DuPontEngineering Polymers will be ratedto facilitate customer selection.

The Unterwriter Laboratories UL 94is widely recognized as an estab-lished selector for B&C products.

UL 94 HB, V2, V1, V-0, 5V areused as criteria to differentiateplastic materials for flammabilitybehaviour. The glow wire test iswidely established in Europe todifferentiate thermoplastic insula-tion material. IEC 60695-2-1 isthe appropriate standard which isshown in Fig. 3.

CTI Comparative TrackingIndexThe CTI is one of the key electri-cal tests carried out to differentiateand select thermoplastic materialsaccording to cost performance.

It is performed to determine thesafety of components carrying liveparts. According to IEC 60112 andUL 746, it indicates the voltage atwhich a material continues to resisttracking. According to Europeanstandards for direct support of live

parts, a CTI greater than 175V isrequired. A more rigorous test isthe CTIM requirement which isdescribed in the DuPont Electricalbrochure Comparative Test methods, TRG 1424. Generallyspeaking, most semi-crystallineengineering polymers carry a CTIof > 175 V. However, it should benoted that all results are based ontests with materials in their naturalcolours and that certain additives(such as colour pigments andfillers) require a detailed investi-gation when used in the formula-tion of a given material (Fig. 4).

Fig. 2. Selection of DuPont Engineering Polymers in accordance with UL 94

Crastin® PBT HB HB HB HB V0 V0 V0 V0

Delrin® acetal HB HB HB HB — — — —

Rynite® PET — HB HB — — V0 — —

Zytel® HTNHigh Temperature — HB — — — V0 — —Nylon

Zytel® nylon V2 HB HB V2 V0 V0 — V0

Zenite® LCPLiquid Crystal — V0 — — — V0 — —Polymer

Hytrel® TEEE HB — HB HB V2/V0 — V2/V0 —

Non FR

extrusionT/ST technologyreinforcedunreinforced

FR

extrusionT/ST technology

reinforcedunreinforced

Almost all DuPont engineering products carry an UL 94 yellow card— = Not available

Fig. 3. Glow wire test 1 mm according to IEC 60695-2-1

Crastin® PBT 650 650 650 650 960 960 960 960

Delrin®

acetal 550 — 550 550 — — — —

Rynite® PET — 650 650 — — 960 — —

Zytel® HTNHigh Temperature — 850 — — — 960 — —Nylon

Zytel® nylon 850 850 750 750 960 960 — 960

Zenite® LCPLiquid Crystal — 960 — — — 960 — —Polymer

Hytrel® TEEE 650 — 650 — 960 — 960 —

Non FR

extrusionT/ST technologyreinforcedunreinforced

FR

extrusionT/ST technology

reinforcedunreinforced

GW 650750 Ask your local DuPont representative for information about glow wire testing.850 A broad range of products can be made available to fulfill these requirements.960

6

Delrin®

7

Thermal testingThermoplastic materials softenwith increasing temperatures. To differentiate their functional performance, the three most rele-vant test methods for the B&Cindustry are detailed below.

UL 746 B-RTI: this relative tem-perature index indicates the mat-erial’s ability to retain particularproperties (electrical, mechanical)when exposed to elevated temper-atures for long periods of time (up to 60,000 hours). This indexis further defined in relation toimpact performance (Fig. 5).

For ball pressure tests (BPT) (in accordance with IEC 60335-1):see DuPont brochure, ComparativeTest method TRG 1424 whichdescribes performance at elevatedtemperatures for the company’scomplete engineering polymersproduct portfolio.

Fig. 4. CTI test according to UL 746

Crastin® PBT 0 3 3 0 2 3 3 2

Delrin®

acetal 0 — — 0 — — — —

Rynite® PET — 3 3 — — 2 — —

Zytel® HTNHigh Temperature — 2 — — — 2 — —Nylon

Zytel® nylon 0 1 0 0 0 2 — 0

Zenite® LCPLiquid Crystal — 2 — — — 2 — —Polymer

Hytrel® TEEE 0 — — 0 3 — 3 —

Non FR

extrusionT/ST technologyreinforcedunreinforced

FR

extrusionT/ST technology

reinforcedunreinforced

Class 0 (≥ 600V)1 (400-600 V)2 (275-400 V)3 (175-250 V)

Fig. 5. RTI performance according to V0 UL 94 746B (electrical)

Crastin® PBT ➍ ❸ ❸ ➍ ➍ ❷ ❸ ➍

Delrin®

acetal ➍ ❸ ➍ ➍ — — — —

Rynite® PET — ❷ ❸ — — ❶ — —

Zytel® HTNHigh Temperature — ❷ — — — ❶ — —Nylon

Zytel® nylon ❸ ❸ ❸ ❸ ❷ ❷ ❸ ❷

Zenite® LCPLiquid Crystal — ❶ — — — ❶ — —Polymer

Hytrel® TEEE ➍ — — ➍ ➍ — ➍ —

Non FR

extrusionT/ST technologyreinforcedunreinforced

FR

extrusionT/ST technology

reinforcedunreinforced

❶ = RTI > 150°C ➋ = RTI ≤ 150°C ❸ = RTI ≤ 130°C ➍ = RTI ≤ 100°C

(available in the respective product range)

(available in the respective product range)

Zytel®

Zytel® HTN

8

HDT, heat deflection temperatureaccording to ISO 75: indicatesproduct performance at elevatedtemperatures while supporting aload. Unlike amorphous materi-als, semi-crystalline products suchas DuPont Engineering Polymerscan be used at temperatures wellabove the HDT, dependant onfactors such as load and time (Fig. 6).

Post treatment technologies forDuPont Engineering PolymersEase of integration, using avail-able post-treatment processes, area substantial factor in the costreduction of a finished part.

Post-treatment could be differen-tiated into two areas labelledproactive and reactive.

Proactive post-treatment will helpto add value to the semi-finishedcomponent, including:• assembly technologies such as

- welding (hot plate, rotationwelding, vibration welding,ultrasonic welding)

- snap fit (use caution whenusing a snap fit one way assembly)

- ability to be riveted (metalrivets)

- press fit, etc.

• decoration technologies such as- hot foil stamping- painting- printing- laser marking or a combinationof these

- vacuum metallisation- plating- two component moulding

All these added-value post opera-tions provide extra value to theapplication for requirements suchas:MID - Moulded InterconnectDevicesSMD - Surface Mount DevicesEMI - Electromagnetic Interference Shielding

Hard/soft combinations as a func-tional requirement should also beconsidered.

Rynite® PET

Hytrel®

Delrin® and Zytel®

Fig. 6. HDT performance of DuPont Engineering Polymers at 1.80 MPA

Crastin® PBT � � � � � � � �

Delrin®

acetal � � � � — — — —

Rynite® PET — � � — — � — —

Zytel® HTNHigh Temperature — � — — — � — —Nylon

Zytel® nylon � � � � � � � �

Zenite® LCPLiquid Crystal — � — — — � — —Polymer

Hytrel® TEEE � — � � � — � —

Non FR

extrusionT/ST technologyreinforcedunreinforced

FR

extrusionT/ST technology

reinforcedunreinforced

� = HDT ≤ 100°C � = HDT 100 - 200°C � = HDT 200 - 250°C � = HDT > 250°C

(available in the respective product range)

QMFZ2 December 30, 1997Component - PlasticsE I DUPONT DE NEMOURS & CO INC E41938 (M)

(L020 - cont. from L015 card)Note: Material designations that are color pigmented may be followed by suffix letters and numbers.#Minimum density is 60.7 PCF (1.03 g/cc).+ Virgin and Regrind from 1% to 50% by weight inclusive, have the same basic material characteristics.++ Minlon is designated Zytel in Japan.+++ “Zytel” may be designated “Maranyl” in Japan.@ Supplied in Black color.(f1) Suitable for outdoor use with respect to exposure to Ultraviolet Light, Water Exposure andImmersion in accordance with UL 746C.(f2) Subjected to one or more of the following tests: Ultraviolet Light, Water Exposure or Immersion inaccordance with UL 746C, where the acceptability for outdoor use is to be determined by ULI.(f3) Refer also to guides FDNP-2 and IQDY-2 for additional information regarding suitability for use inNSF 61 and NSF 51 applications.Replaces E41938L020 dated January 16, 1997. (Cont. on M card)324299147 Underwriters Laboratories Inc. D1I/0243370

45

9

DuPont invests considerableresources into research and devel-opment for its engineering polymerproduct line. The enclosed resultsare confined to already-publisheddata; further information is pub-lished on an ongoing basis.

One of the most exciting R&Dareas concerns DuPont’s activitiesin the recycling of thermoplasticengineering polymers. Followingpart integration and miniaturisation,recycling has the next largestpotential area of cost reduction for a wide range of product applications.

It is specified that up to 25% ofthe initial resin can be re-used inexisting applications, as definedfor all DuPont EngineeringPolymers in compliance with UL 746B.

In addition, DuPont has variousproducts available with a recyclingrate of up to 50%. This substantialcontribution to customer costreduction was achieved throughin-depth product and processingperformance evaluation which isalso available from your localDuPont representative.

Research and Development

Institute of low-voltageswitching devices. With the courtesy of theTechnical University,Vienna.

Fig. 7

QMFZ2 May 15, 1997Component - Plastics

E I DUPONT DE NEMOURS & CO INC E41938 (M)(A005 - cont. from A card)

E42NC 0.81 94HB - - - 4 0 - - -

1.5 94HB - - - 2 0 - - -

3.0 94V-2 - - - 2 0 0 5 0

45HSB+All 0.71 94HB 140 95 115 4 0 - - -

1.5 94HB 140 110 125 4 0 0 - 03.0 94HB 140 110 125 3 0 1 6 -

101(f2)+, 101F+,All 0.71 94V-2 130 75 85 4 0 - - -

101L+,1.5 94V-2 130 75 85 3 0 0 - -

E101L+, E101(f1)+,3.0 94V-2 130 75 85 2 0 0 6 0

132F+, 133L+, 135F+6.0 94V-2 130 75 85 2 0 0 - -

Reports: July 29, 1996; July 30, 1996; July 29, 1996.Replaces E41938A005 dated April 14, 1997. (Cont. on A010 card)

324299147 N7047 Underwriters Laboratories Inc.® D1I/0236590338

Up to 50%

10

DuPont Engineering Polymers arefast becoming the new industrystandard materials for the B&Cindustry, replacing thermosets inmany miniature circuit breakerapplications (MCBs) of up to 63Amp. nominal current.

The flammability, thermal andelectrical properties of these polymers, in combination withmechanical features such asdimensional stability, have estab-lished a proven track record forreliability, high quality, recyclingand cost reduction in today’s market place.

The optimal economics of multi-functional chassis design and easeof processing have made engi-neering polymers an ideal choicefor protective devices.

According to EN 60898 forhousehold overload protectionand similar applications, DuPont’sThermoplastic EngineeringPolymer portfolio provides anexcellent fit when key criteria likeflame retardency, CTI, thermalbehaviour, dimensional propertiesand cost are taken into considera-tion. Fig. 8 demonstrates thestrength of the complete DuPontproduct offering.

Protection

Fig. 8. DuPont offering for MCB housings

This summary indicates a selection of most stringent MCB requirements. The final choice of resin will always depend upon thespecific requirements of a particular application.

HB

V2

V1

V0

5V

UL 94

Ultras

onic

welding

Snap f

itBothAsse

mbly

technolo

gy

≥ 200

≥ 150

≥ 100

≥ 50

4 3 2

Very low Low High

1 0

UL RTIelectrical test

>1%

>5%

>10%

>15%

Moisture pickup

saturated

300

250

150

200

50

100

HDT 0,8 M

Pa

Glow wire

550

650

750

850

960

Nowarpage

CTIUL 746 B

Colour Ral 7035

11

Examples of the DuPontoffering for protection applications

12

Materials requirements forswitches, micro switches andpush buttons are similar to thosefor contactors

Control

Like circuit breakers, switch gear applications require certainadditional features for their designwhich take into account increasedlife cycle test methodology andreliable thermal and electricalperformance. To support theserequirements, special resins havebeen designed with features suchas arc-quenching or low out-gassingperformance, as well as reliabilityat elevated temperatures. Fig. 9provides an indication of whichproducts test meet a givenrequirement.

The following range of specificgrades of DuPont high perfor-mance polymers: Crastin® PBT,Kapton®, Mylar®, Nomex®,Rynite® PET, Zytel®, Zytel® HTN,Zenite® LCP are compatible withthe insulation components listedin UL File E75735 - the mostextensive material selection guideavailable.

Wear resistanceAs a critical part of the DuPontoffering for control applications,the wear resistance of the polymersupporting the contact must betaken into consideration.

Requirement Solution 1 Solution 2 Solution 3

Arc Zytel® 101L Delrin® 500 Zytel® EFE7298quenching

Low Crastin® PBT SK645 Crastin® PBT CE7931 Zenite® LCP 6130outgassing

UL94 Almost all FR gradesV0

UL94 Zytel® 101L Zytel® FR70G25V0 Zytel® FR70M40GWV2

CTIA variety of different products≥ 250V

CTI Crastin® PBT LW9020FR Crastin® PBT LW9330FR Crastin® PBT LW9320FR≥ 300V

Halogen and red Zytel® FR7026V0F Zenite® LCP 3130L Zenite® LCP 6130phosphorous freeflame retardant

Fig. 9. Requirement for control components

13

Examples of DuPont offering for control applications

14

Insulation and encapsulationAs a mark of its commitment tothe control industry, DuPontoffers a unique portfolio of insula-tion and encapsulated systemsfrom Class B 130°C to R 220°Caccording to UL 1446. This cov-ers systems such as transformers,contactors, motors and starters upto 600 Volts.

DuPont insulation materials offera unique combination of thermalstability, electrical and mechanicalproperties and flammability rat-ings up to 5 V, according UL 94.

The DuPont encapsulation systemsalso offer reduced processingsteps with substantial cost reduction potential for insulationsystems.

Fig. 10. Comparison and classification of electrical insulation and encapsulation systems according to UL 1446

UL94 UL 1446/IEC 60085Flammability Encapsulation

Generic % Glass at 0,8 mm Recognition

ZYTEL® nylon101L PA66 — V2 –70G33L PA66 33 HB –FR70G25V0 PA66 25 V0 –5429ER PA66 33 HB Class B

ZYTEL® nylon“Electrical / Sensor Resins”FE5382 BK276 PA612 33 – –FE5389 BK276 PA66 33 – –

ZYTEL® HTN

HTN 51G35HSL NC010 HTN 35 HB –HTN FR51G35L NC010 HTN 35 V0 –

CRASTIN® PBT PolyestersT803 PBT 20 HB –T805 PBT 30 HB –T841FR PBT 10 V0 –T843FR PBT 20 V0 –T845FR PBT 30 V0 –

RYNITE® PET Polyesters415HP PET 15 HB –FR515 PET 15 V0 –530 PET 30 HB –FR530 PET 30 V0 –

RYNITE® PET

“Electrical Specialty Resins”815ER PET 15 HB Classes B, F830ER PET 30 HB Class HFR815ER PET 15 V0 –FR830ER PET 30 V0 Class B

ZENITE® LCP

6130 WT010 LCP 30 V0 –

Potted Coil HousingsCRASTIN® PBT

LW9020 PBT/ASA 20 HB –LW9030 PBT/ASA 30 HB –LW9020FR PBT/ASA 20 V0 –LW9030FR PBT/ASA 30 V0 –

RYNITE® PET

935 PET 35 mica /glass HB –530 PET 30 HB –FR530 PET 30 V0 –

Rynite® PET

Crastin® PBT

15

EN 60309 (former 4343/VDE0623) covers the critical segmentof a range of major industrialapplications such as plugs, socketoutlets and couplers. Industrialplug/socket IEC 60884 and EN 60998 cover most of the residential plugs and sockets anddevices for low voltage circuits.

Most DuPont EngineeringPolymers fulfil the above-mentioned requirements for non-contact carrying parts.

For the more stringent require-ments of components in proximi-ty with contact-carrying parts, arange of Crastin®, Rynite®, Zytel®,Zytel® HTN and Zenite® resins areavailable. Most can be identifiedby their code which carry an FR(flame retardant) symbol. OnlyZenite® is inherently flame retar-dant.

Wiring devices

Zytel® ST

Crastin® PBT

16

Fig. 11 gives recommendationsfor the usage of DuPont resins inthese applications: Application Needs Recommended resin

Residential Gloss, colour Zytel® 101Lwall plate static dissipation Crastin® S600F10

Residential GW960, CTI Zytel® FR70M30V0contact carrier low warpage Zytel® FR70M40GW

Industrial plug Impact strength Zytel® 101Lhousing GW, colour Zytel® 408

Zytel® ST801HS

Industry contact GW/V0, dimensional Zytel® FR70M30V0carrier stability low wear Crastin® LW9020FR

Crastin® LW9320FR

Industrial plug Dimension stability Zytel® FR7026V0Fsocket housing RAL 7035/7032 Crastin® S650FR

Crastin® S680FRCrastin® CE1064

Terminal block UL 94 V2/CTI, Zytel® 103HSLRTI, colour Zytel® 101L

Terminal block UL 94 V0 Zytel® FR7026V0FCTI 600 Volt, colourhalogen free

Print connectors UL 94 V0 Zytel® FR7026V0FCTI colour Crastin® T841FRRTI > 80°C Crastin® T843FR

Crastin® LW9020FRCrastin® LW9320FR

Industrial/ Impact strength/colour Zytel® FR7026V0Fbusshousing dimensional stability V0 Crastin® S650FR

Crastin® S680FRCrastin® CE1064

Industrial/ Stiffness impact Crastin® SK645FRbussbars adapters strength, UL 94 V0 Rynite® FR530L

Zytel® FR70G25V0

Fig. 11. Recommendations for the usage of DuPont resins

Fig. 12. Typical applications such as enclosures, structural parts, cable support components as cable ties,clamps, snap fits, chains, release devices

Requirements

Glow wire CTI RTI electrical Warpage Stiffness Toughness≥ 850 C ≥ 650 V ≥ 175V ≥ 120C flexibility

Product selection

Zytel® unreinforced ▲■ ■ ■ ■ ▲ ▲ ● ■

Zytel® glass reinforced ● ■ ■ ■ ■ ▲ ● ■ ●

Minlon® mineral reinforced ● ■ ■ ■ ■ ● ▲ ▲ ●

Crastin® PBT unreinforced ● ■ ■ ■ ■ ● ▲ ● ■

Crastin® PBT glass reinforced ● ■ ■ ■ ■ ■ ● ■ ●

Crastin® PBT blend glass reinforced ● ■ ■ ■ ■ ■ ▲ ■ ●

Rynite® PET glass reinforced ● ■ ■ ■ ■ ■ ● ■ ●

Zytel® HTN glass reinforced ● ■ ■ ■ ■ ■ ● ■ ●

Hytrel® TEEE unreinforced ● ■ ■ ■ ● ▲ ● ■

Glow wire at 3 mm wall thickness according to TKG 1424

❚❚❚ standard non FR grade❚❚❚ FR - flame retardant grade

● low potential candidate▲ potential candidate■ high potential candidate

17

18

In compliance with EN 60670(the former VDE 0606 Europeanstandard for the enclosures ofhousehold and similar fixed elec-trical installations) two require-ments on glow wire cup are:

- for current carrying parts > 850°C

- none current carrying parts > 650°C

Select DuPont EngineeringPolymers for structural parts from Fig. 13 (except large flatpanel designs).

DuPont also provides resins forrod stock and shapes for use in theBranching and Control industry.

Additional requirements forBranching & Control extrusionapplications and their end-usesare shown in Fig. 13.

Some of these grades (marked *)offer halogen-free, flame retar-dency which minimize the toxici-ty and corrosion in case of fire.

Secondary protection

Glow wire

Applications ≤ 650°C ≥ 650°C

Cables Crastin® S600 F10* Zytel® 101/103HSL*

Cable tubes & Zytel® 101/103HSL *

corrugated tubes Zytel® 73G30 * Zytel® FR7026V0F *

Direct wire coating Hytrel® HTR8303 * Hytrel® HTR8303FR

Delrin® and Rynite® PET

Fig. 13. Typical grades for wire and cable extrusion

19

As already outlined, the need to constantly reduce costs hasbecome a substantial driver in theBranching and Control industry.

This industry trend is posing chal-lenges concerning resin selection,design and assembly.

The comparison on page 20 sum-marises the advantages of thermo-plastics, compared to thermosets.

Technical resources for effective cost reduction

Crastin® PBT

20

In addition to satisfying thedemanding technical requirementsof the B&C industry, thermoplasticresins offer cost advantages overthermosets. Generally, these costsavings more than offset the highermaterial cost. Thermoplastics arealso more environmentallyacceptable.

Thermoplastics give design engi-neers these important benefits:

1. Wall thickness reduction2. Function integration3. Ease of assembly4. Processing advantages5. No need for finishing

operations6. Higher productivity7. Simplified packaging8. Reduced waste concerns

1. Wall thickness reductionDepending on the application,reductions of up to 50% in wallthickness have been achievedusing thermoplastics. Thesereductions result directly from thesuperior mechanical properties ofthermoplastics, including addedtensile strength and impact resis-tance. Such reductions positivelyaffect moulding cycle times.

2. Function integrationIt is well known that engineeringthermoplastics lend themselvesmore than thermosets to part inte-gration, replacing costly partassembly. For example, the elon-gation of polyamides can be usedto make junction blocks easy tofasten onto fixation rails.

3. Ease of assemblyThe higher elongation strengthand other favourable characteris-tics of thermoplastics lead to arange of assembly techniqueswhich are difficult or even impos-sible to realise with thermosets.These include the use of self-tap-ping screws, snap-fits, press-fits,moulded-in hinges, ultrasonicwelding and riveting.

Thermoplastics versus thermosets: a cost comparison for Branchingand Control devices

Rynite® PET

Zytel®

21

Another advantage of thermo-plastic parts is that they are lesssusceptible to breakage duringassembly operations since theyare very tough. This factor cansometimes lead to faster assemblylines.

4. Processing advantages

A. - Cycle timesCycle times are generally two tofour times shorter for thermoplas-tics, compared with compressionmoulding, and faster in thick sections, compared with thermosetinjection moulding. Since thermo-

plastic parts are usually thinnerparts than thermosets, the cycleadvantage is even bigger.

B. - YieldsDirect processing yields are higherwith thermoplastics. This is mainlyrelated to part breakage that occurswhile processing thermosets.

C. - Resin re-useSprues and runners in thermoplas-tics can be reprocessed without

affecting part properties. The use of runnerless moulding is also generally possible, which is normally not the case with thermosets.

D. - Tool costsTooling costs are generally slightlyhigher for moulding thermosets.The service life of the tools is alsosomewhat shorter than it is withthermoplastics, due to higherabrasion with thermosets.

E. - Shelf life of thermosetsThermoset resins often have alimited shelf life, measured in

weeks or months. Proper facilitiesfor their storage may sometimesrequire a conditioned environment.This is not the case for thermo-plastic resins.

F. - Machine settingsAs some thermoset resins have a tendency to start their cross-linking process in storage,moulding conditions may have to be re-adjusted between twoproduction runs, which can leadto higher costs.

5. Finishing operationsDeflashing after moulding is notrequired for parts in thermoplastics.Not only is deflashing an additionalcost with thermosets, but it isoften the cause of additional partbreakage.

6. Higher productivityThroughout manufacturing andshipping operations, productivityis much higher with thermoplasticsthan with thermosets. Thermo-plastics can be moulded faster, andthere is less breakage during pro-cessing, deflashing, parts assembly,packaging and installation.

7. PackagingThe superior impact resistance ofthermoplastics makes them muchless susceptible to breakage duringshipping and handling in general.In many cases, this can lead toless expensive packaging.

8. Waste disposalToday, the safe disposal of ther-moset flashes and broken partshas become a real environmentalconcern. These problems can beavoided by using thermoplastics.

Your local DuPont representativewill help you complete a thoroughanalysis, if needed.

Zytel® and Thermoset

22

All the parameters brieflyreviewed in this brochure showthat there are many advantages tousing thermoplastics, despite theirhigher material cost. Thisbecomes clear when calculatingthe total cost of the finished part,as opposed to the finished item.

A material selection check list forbranching and distribution devicecomponents in thermosets andthermoplastics is shown on thefollowing page.

DuPont is ready to assist you ingoing through your own part costcalculation, or to comment on anyof the points in the check list thatfollows.

Summary

To simplify the selectionof the best product foryour application, DuPonthas developed a QualityFunction Deployment(QFD) spreadsheet thatshould be filled in beforethe first project meeting.

A copy of this form isreproduced on the nextpage.

Please fill in the blankswith your identifiedneeds and quantify them.Also, don’t forget tomention your priorities inthe column rating.

Then, send your requestto your local DuPontcontact, who will provideyou with a selection offunctional candidates.

Rating (10 high, 5 low)Halogen

PhosphorousH & p free

HBV2V1V0

Glow wire testOxygen index or I/F rating

Comparative tracking index (CTI)CTI > 175 VCTI > 400 VCTI > 600 V

Arc resistance(s)Dielectrical strength (KV/mm)

Where thickness = 2,3 mmWhere thickness = 3,2 mm

Volume resistivity (ohm x cm)Coefficient of linear thermal expansion

Water absorptionWarpage

Tensile strengthElongation at breakTensile E - modulus

Charpy impact strength - unnotched- notched

Temp. of deflection under load at 1,8Relative temperature index (RTI)

ElectricalMechanical with impact

Mechanical without impactSurface treatment / printing

Surface treatment laser printingColouring according to RAL card

Surface gloss requirementsAcid (indicate PH level)

Leach (indicate PH level)Solvent (indicate type)

Tool runner / system standard cold- hotrunner

Max. flow length in cavityMould deposit

Mould shrinkageTool & machine wear

Tool surface temperatureSnap fit assemblyScrew fit assemblyPress kit assemblyWeld fit assembly

Soldering techniqueResin price per litre

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Application:

Material 1:

Material 2:

Material 3:

Real c

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1.Type of flam

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2.Flam

mability rating

3.Electrical properties

4.D

imensional stability

5.M

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6.Therm

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7.D

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8.C

hemical resistivity

9.Processing

10.Assem

bly techniques

11.Econom

ics

®

© DuPont 23

12.99 Printed in SwitzerlandL-12118 ® DuPont registered trademark DuPont Engineering Polymers

For further information on Engineering Polymers contact:Belgique / BelgiëDu Pont de Nemours (Belgium)Antoon Spinoystraat 6B-2800 MechelenTel. (15) 44 14 11Telex 22 554Telefax (15) 44 14 09

BulgariaServiced by Interowa.See under Österreich.

C̆eská Republika aSlovenská RepublikaDu Pont CZ, s.r.o.Pekarska 14/268CZ-155 00 Praha 5 – JinoniceTel. (2) 57 41 41 11 Telefax (2) 57 41 41 50-51

DanmarkDu Pont Danmark A / SRoskildevej 163Post Boks 139DK-2620 AlbertslundTel. 43 62 36 00Telefax 43 62 36 17

DeutschlandDu Pont de Nemours (Deutschland) GmbHDuPont Straße 1D-61343 Bad HomburgTel. (06172) 87 0Telex 410 676 DPD DTelefax (06172) 87 27 01

EgyptMedgenco International Trade Co.13, El Bostan StreetET-CairoTel. (02) 392 78 66Telex 93 742 MK UNTelefax (02) 392 84 87

EspañaDu Pont Ibérica S.A.Edificio L’IllaAvda. Diagonal 561E-08029 BarcelonaTel. (3) 227 60 00Telefax (3) 227 62 00

FranceDu Pont de Nemours (France) S.A.137, rue de l’UniversitéF-75334 Paris Cedex 07Tel. 01 45 50 65 50Telex 206 772 duponTelefax 01 47 53 09 67

HellasRavago Plastics Hellas ABEE8, Zakythou Str.GR-15232 HalandriTel. (01) 681 93 60Telefax (01) 681 06 36

IsraëlGadot Chemical Terminals (1985) Ltd.22, Shalom Aleichem StreetIL-633 43 Tel AvivTel. (3) 528 62 62Telex 33 744 GADOT ILTelefax (3) 528 21 17

ItaliaDu Pont de Nemours Italiana S.p.A.Via Aosta 8I-20063 Cernusco sul Naviglio (Mi)Tel. (02) 25 30 21Telefax (02) 92 107 845

MagyarországServiced by Interowa.See under Österreich.

MarocDeborel Maroc S.A.40, boulevard d’Anfa - 10o

MA-CasablancaTel. (2) 27 48 75Telefax (2) 26 54 34

NorgeDistrupol Nordic Niels Leuchsvei 99N-1343 EiksmarkaTel. 67 16 69 10Telefax 67 14 02 20

ÖsterreichInterowaFürer-Haimendorf GmbHBräuhausgasse 3-5A-1050 WienTel. (01) 512 35 71Telex 112 993 IROWA ATelefax (01) 512 35 71 12 /

512 35 71 31

PolskaDu Pont Poland Sp. z o.o.ul. Prosta 69PL-00-838 WarszawaTel. (022) 691 09 01Telefax (022) 691 09 10

PortugalACENYLRua do Campo Alegre, 672 - 1o

P-4100 PortoTel. (2) 69 24 25 / 69 26 64Telex 23 136 MACOLTelefax (2) 600 02 07

RomaniaServiced by Interowa.See under Österreich.

RussiaE.I. du Pont de Nemours & Co. Inc.Representative OfficeB. Palashevsky Pereulok 13 / 2SU-103 104 MoskvaTel. (095) 797 22 00Telex 413 778 DUMOS SUTelefax (095) 797 22 01

Schweiz / Suisse / SvizzeraDolder AGImmengasse 9Postfach 14695CH-4004 BaselTel. (061) 326 66 00Telex 962 306 DOL CHTelefax (061) 326 62 04

SlovenijaServiced by Interowa.See under Österreich.

Suomi / FinlandDu Pont Suomi OyPiispankalliontie 17PO Box 199FIN-02201 EspooTel. (9) 72 56 61 00Telefax (9) 72 56 61 66

SverigeDuPont Sverige ABBox 23S-164 93 Kista (Stockholm)Tel. (8) 750 40 20Telefax (8) 750 97 97

TürkiyeDu Pont Products S.A.Turkish Branch OfficeSakir Kesebir cad. Plaza 4No 36 / 7, BalmumcuTR-80700 IstanbulTel. (212) 275 33 82Telex 26541 DPIS TRTelefax (212) 211 66 38

UkraineDu Pont de NemoursInternational S.A.Representative Office3, Glazunova StreetKyiv 252042Tel. (044) 294 96 33 / 269 13 02Telefax (044) 269 11 81

United KingdomDu Pont (U.K.) LimitedMaylands AvenueGB-Hemel HempsteadHerts. HP2 7DPTel. (01442) 34 65 00Telefax (01442) 24 94 63

ArgentinaDu Pont Argentina S.A.Avda. Mitre y Calle 5(1884) Berazategui-Bs.As.Tel. (541) 319-44 84 / 85 / 86Telefax (541) 319-44 17

BrasilDu Pont do Brasil S.A.Al. Itapecuru, 506 Alphaville06454-080 Barueri-São PauloTel . (5511) 421-84 68 / 85 56

Asia PacificDu Pont Kabushiki KaishaArco Tower, 14th Fl.8-1, Shimomeguro 1-chomeMeguro-ku, Tokyo 153Tel. (03) 54 24 61 00

South AfricaPlastamid (Pty) Ltd.43 Coleman StreetP.O. Box 59Elsies River 7480Cape TownTel. (21) 592 12 00Telefax (21) 592 14 09

USADuPont Engineering PolymersBarley Mill Plaza, Building #22P.O. Box 80022Wilmington, Delaware 19880Tel. (302) 892 05 41Telefax (302) 892 07 37

Requests for further information from countries not listed aboveshould be sent to:

Du Pont de NemoursInternational S.A.2, chemin du PavillonCH-1218 Le Grand-SaconnexGenevaTel. (022) 717 51 11Telex 415 777 DUP CHTelefax (022) 717 52 00

Internet location:http://www.dupont.com/enggpolymers/europe

The information provided in this documentation corresponds to our knowledge on the subject at the dateof its publication. This information may be subject to revision as new knowledge and experiencebecomes available. The data provided fall within the normal range of product properties and relate onlyto the specific material designated; these data may not be valid for such material used in combination withany other materials or additives or in any process, unless expressly indicated otherwise. The data providedshould not be used to establish specification limits nor used alone as the basis of design; they are notintended to substitute for any testing you may need to conduct to determine for yourself the suitabilityof a specific material for your particular purposes. Since DuPont cannot anticipate all variations in actualend-use conditions DuPont makes no warranties and assumes no liability in connection with any use ofthis information. Nothing in this publication is to be considered as a license to operate under or a rec-ommendation to infringe any patent rights.Caution: Do not use this product in medical applications involving permanent implantation in the humanbody. For other medical applications see “DuPont Medical Caution Statement”, H-50102.