01906 01a Fundamentals

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1Fundamentals

INTRODUCTIONThis chapter reviews information pertinent to the processing of a diversegroup of plastics that are summarized in Figs 1.1 to 1.3. There are manydifferent types of plastics processed by different methods to produceproducts meeting many different performance requirements, includingcosts. This chapter provides guidelines and information that can be fol-lowed when processing plastics and understanding their behavior duringprocessing. The basics in processing relate to temperature, time, andpressure. In turn they interrelate with product requirements, includingplastics type and the process to be used (Fig. 1.4). Worldwide plasticsconsumption is at least 200 billion tons; the estimated use by process isshown in Table 1.1. In the United States it is estimated that about 70000injection molding machines (IMMs), 14000 extruders and 6000 blowmolders (BMs)are in about 22000 plants with annual sales of about $20billion [1-93].


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THE COMPLETE PROCESSING OPERATIONFALLO APPROACHS O F T W A R EO P E R A T I O N H A R D W A R EO P E R A T I O N S O F T W A R EO P E R A T I O N

S E T R E Q U I R E M E N T SD E S I G N P A R TO R G A N I Z E P L A N T

B A S I CP R O C E S S I N GM A C H I N EM O L D / D I E

f o l l o w i n gP R O D U C T I O Ns t a r t a g a i nand

REEVALUATED E S I G N ,P L A S T I C ,P R O C E S S I N G L I N EM A T E R I A L H A N D L I N GA U X I L I A R Y E Q U I P M E N T


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Per formance R e q u i r e m e n t s

PracticalApproach Eng ineer ingApproach

Mate r i a l Select ion

Properties Processes Cost

Idea l choice/CompromiseFigure 1.2 Product manufacture: a simplified flow diagram.

Table 1.1 Plastics consumption by processesExtrusion 36%Injection 32%Blow 10%Calendering 6%Coating 5%Compression 3%Powder 2%


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N A T U R A L G A S PETROLEUM C O A L AGRICULTURE

ETHANE PROPANE BENZENE N APHTHA BUTENE

ETHYLENE STYRENE FORMA LDEHYDE POLYOL ADIPATEPROPYLENE VINYL CHLO RIDE CUMENE AC RYLIC

POLYETHYLENE POLYSTYRENE AC ETAL POLYCA RBON ATEPOLYPROPYLENE POLYVINYLCHLORIDE NYLON

EXTRUSION INJECTION B L O W CAL E N D E R CO AT I N G

BUILDING P ACK AGIN G T R AN S P O R T AT IO N R E CR E AT IO NELECTR ICA L CONSUMER INDUSTRIAL

PIPE APPLIANC E PACKA GING LUGGA GE MARINE S IGN TOYSIDING COMM UNICATION ELECTRICA L MEDICAL AU TO TOO L

Figure 1.3 Simplified flowchart of plastics from raw materials to products.

ENERGYS O U R CE S

FEEDSTOCKS

M O N O M E R S

PLASTICS

FABRICATION

M AR K E T S

PRODUCTS


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ProductsP r o p e r t i e sA p p e a r a n c eC o s t

ResinD e n s i t yM e l t I n d e xM o I . W t . D i s t r i b u t i o nA d d i t i v e s

ProcessT e m p e r a t u r eP r e s s u r eC y c l eMo l d A n d P r o c e s s D e s i g nFigure 1.4 Interrelation of products, resin, and process.

specific process (injection, etc.) is an important part of the overall schemeand should not be problematic. The process depends on several interre-lated factors: (1)designing a part to meet performance and manufacturingrequirements at the lowest cost; (2) specifying the plastic; (3) specifyingthe manufacturing process, which requires (a) designing a tool 'around'the part, (b)putting the 'proper performance' fabricating process aroundthe tool, (c)setting up necessary auxiliary equipment to interface with themain processing machine, and (d) setting up 'completely integrated' con-trols to meet the goal of zero defects;and (4) 'properly' purchasing equip-ment and materials, and warehousing the materials [1-9].

Major advantages of using plastics include formability, consolidationofparts, and providing a low cost-to-performance ratio. For the majority of


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pressures allow the development of tighter dimensional tolerances withhigher mechanical performance; but there is also a tendency to developundesirable stresses (orientations) if the processes are not properly under-stood or controlled. A major exception is reinforced plastics processing atlow or contact pressures (Chapter 12). Regardless of the process used, itsproper control will maximize performance and minimize undesirableprocess characteristics.

PRODUCT REQUIREMENTS AND MACHINE PERFORMANCEAlmost all processing machines can provide useful products with relativeease, and certain machines have the capability ofmanufacturing productsto very tight dimensions and performances. The coordination of plasticand machine facilitates these processes. This interfacing of product andprocess requires continual updating because of continuing new develop-ments in manufacturing operations. The information presented in thisbook should make past, present and future developments understandablein a wide range of applications.

Most products are designed to fit processes of proven reliability andconsistent production. Various options may exist for processing differentshapes, sizes and weights (Table 1.2). Parameters that help one to selectthe right options are (1)setting up specific performance requirements; (2)evaluating material requirements and their processing capabilities; (3)designing parts on the basis of material and processing characteristics,considering part complexity and size (Fig. 1.5) as well as a product andprocess cost comparison; (4) designing and manufacturing tools (molds,dies, etc.) to permit ease of processing; (5) setting up the complete line,


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Table 1.2 Competitive processes

Matchedmold , sprayCompress ionand transfermoldingRotat ionalmolding

React ioninjectionmoldingT he r mo -f ar m i ngBlowmoldingxtrus ionInjectionmolding

222

12

2

1

111

2, B2

2

11

22

2, A12, A

22

1

1

2

11, C

Bottles, necked 2, Acontainers, etc.Cups, trays, open 1containers, etc.Tanks, drums, largehollow shapes,etc.Caps, covers, 1closures, etc.Hoods, housings, 1auto parts, etc.Com plex shapes, 1thickness changes,etc.Linear shapes, pipe, 2, Bprofiles, etc.Sheets, panels,laminates, etc.

1 = prime process.2 = secondary process.A = combine two or more parts with ultrasonics, adhesives, etc. (Chapter 17).B = short sections can be molded.C = also calendering process.


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including auxiliary equipment (Fig. 1.1 and Chapter 16); (6) testing andproviding quality control, from delivery of the plastics, through produc-tion, to the product (Chapter 16); and (7) interfacingall these parametersby using logic and experience and/or obtaining a required update ontechnology.

PROCESSINGFUNDAMENTALSPolymers are usually obtained in the form of granules, powder, pellets,and liquids. Processing mostly involves their physical change (thermo-plastics), though chemical reactions sometimes occur (thermosets). Avariety of processes are used. One group consists of the extrusion proc-esses (pipe, sheet, profiles, etc.). A second group takes extrusion andsometimes injection molding through an additional processing stage(blow molding, blown film, quenched film, etc.). A third group consists ofinjection and compression molding (different shapes and sizes), and afourth group includes various other processes (thermoforming, calen-dering, rotational molding, etc.).

The common features of these groups are (1) mixing, melting, andplasticizing; (2)melt transporting and shaping; (3)drawing and blowing;and (4) finishing. Mixing melting, and plasticizing produce a plasticizedmelt, usually made in a screw (extruder or injection). Melt transport andshaping apply pressure to the hot melt to move it through a die or into amold. The drawing and blowing technique stretches the melt to produceorientation of the different shapes (blow molding, forming,etc.). Finishingusually means solidification of the melt.The most common feature of all processes is deformation of the meltwith its flow, which depends on its rheology. Another feature is heatexchange, which involves the study of thermodynamics. Changes in a


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sion, for example, these characteristics include drawdown (hot melt ex-tensibility), pressure and temperature sensitivity, smoke and odor, prod-uct stability during hauloff, and flow rate (which is an operatingcondition). And there are other factors, too (Chapter 3). Often, however,it is not the plastic but unfavorable operating conditions that lead toinadequate plastic performance.

PROCESSESOverviewThe type of process to be used depends on a variety of factors, includingproduct shape and size, plastic type, quantity to be produced, quality andaccuracy (tolerances) required, design load performance, cost limitation,and time schedule. Each of the processes reviewed provides differentmethods to produce different products. As an example, extrusion with itsmany methods produces films, sheet, pipe, profile, wire coating, etc. Someof the process overlap since different segments of the industry use them.Also terms such as molding, embedding, casting, potting, impregnationand encapsulation are sometimes used interchangeably and/or allowedto overlap. However, they each have their specific definitions [9].

Almost all processing machines can provide useful products with rela-tive ease, and certain machines have the capability of manufacturingproducts to very tight dimensions and performances.The coordinationofplastic and machine facilitates these processes; this interfacing requires

P l a s t i c s f l o w a b i l i t yB u l k d e n s i t y Feeding e a s e


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continual updating because of continuing new developments in process-ing operations.During the conversion of plastics into products, various melt-processing procedures are involved. The inherent viscoelastic propertiesof each plastic type can lead to certain undesirable processing defects, soadditives are used to ease these processing-related problems. Examplesare heat and light stabilizers, antioxidants, and lubricants. There are usu-ally many different additives already in the plastics [3, 9]. Some plasticshave limited applications due to their undesirable physical propertiesand/or their poor processing (Fig. 1.6). These limitations have greatlybeen reduced through the use of plastic blends and alloys. Bymixing twoor more plastics, the overall balance of physical and processing propertiescan be optimized. These processing aids are used in such small quantitiesthat their effect on the final physical properties of the major plastic orplastic mixture is minimized.Most processes fit into an overall scheme that requires interaction andproper control of its different operations. There are machines that performmultifunctions. Figure 1.7 shows the world's first machine to combinemore that seven processes; it includes injection molding, flow molding,stamping, coinjection, gas injection, compression molding, flow formingand proprietary processes. This one-of-a-kind machine is 75ft (23m) long,50 f t (15m) wide, and 55ft (17m) tall; it can produce parts up to 6ft (1.8m)square.

Some products are limited by the economics of the process that must beused to make them. For example, hollow parts, particularly very largeones, may be produced more economically by the rotational process thanby blow molding. Thermosets (TSs) cannot be blow molded (to date) andthey have limited extrusion possibilities. The need for a low quantity mayallow certain processes to be eliminated by going to casting. Thermoplas-


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Calendered sheets are limited in their width by the width of the materialrolls, but are unlimited in length. Vacuum forming is not greatly limitedby pressure, although even a small vacuum distributed over a large areacan build up an appreciable load. Blow molding is limited by equipmentthat is feasible for the mold sizes. Rotational molding can produce rela-tively large parts.

Injection molding and extrusion tend to align long-chain molecules inthe direction of flow. This produces markedly greater strength in thedirection of flow than at right angles to the flow. An extruded pressurepipe could have its major strength in the axial/machine direction whenthe major stresses in the pipe wall are circumferential. Proper controls onprocessing conditions allow the required directional properties to be ob-tained. If in an injection mold the plastic flows in from several gates, themelts must unite or weld where they meet. But this process may not becomplete, especially with filled plastics, so the welds may be points ofweakness. Careful gating with proper process control can allow welds tooccur where stresses will be minimal.

Certain products are most economically produced by fabricating themwith conventional machining out of compression-molded blocks, lami-nates or extruded sheets, rods or tubes. It may be advantageous to designa product for the postmolding assembly of inserts, to gain the benefit offully automatic molding and automatic insert installation.

The choice of molder and fabricator places no limits on a design. Thereis a way to make a part if the projected values justify the price; any jobcan be done at a price. The real limiting factors are tool-design considera-tions, material shrinkage, subsequent assembly or finishing operations,dimensional tolerances, allowances, undercuts, insert inclusions, partinglines, fragile sections, the production rate or cycle time, and the sellingprice.


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Figure 1.8 Relationship between manufacturing process and properties ofinjection-molded product.

Machine conditions are temperature, pressure, and processing time (suchas screw rotation in R PM for a screw plasticator), die and mold tempera-ture and pressure, machine output rate (Ib h"1), etc. Processing variablesare more specific than machine conditions: the melt in the die or the moldtemperature, the flow rate, and the pressure used.The distinction between machine conditions and fabricating variablesis important when considering cause-and-effect relationships. If theprocessing variables are properly defined and measured, not necessarilythe machine settings, they can be correlated with the part properties. Forexample, if one increases cylinder temperature, melt temperatures do notnecessarily increase, too. Melt temperature is also influenced by screwdesign, screw rotation rate, back pressure, and dwell times (Chapter 2). It


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Processing methodsTable 1.3 is a very brief review and guide on the different processes. Therelevant chapters give more details, the many exceptions, and anychanges that can occur, particularly limitations.Machine operation terminologyTerminology in the plastics industry regarding the operation of machin-ery is as follows:M a n u a l o p era t io nEach function and the timing of each function is controlled manually byan operator.Semiautomatic o p era t io nA machine operating semiautomatically will stop after performing a com-plete cycle of programmed molding functions automatically. It will thenrequire an operator to start another complete cycle manually.Automatic o p era t io nA machine operating automatically will perform a complete cycle of pro-grammed molding functions repetitively; it will stop ontyfor a malfunc-tion on the part of the machine or mold, or when it is manuallyinterrupted.Plastics memory and processing


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Table 1.3 Plastic processing m ethods preliminary g uideLimi tat ionsescript ionrocess

Generally limited to hollow or tubular parsome versatile mold shapes, other thanbottles and containers.

Limited to sheet materials and very thinfilms are not possible.

Limited to relatively simple shapes.Most thermoplastics are not suitable fo rthis method. Except fo r cast films, methodbecomes uneconomical at high vo lumeproduction rates.

Limited to simple cu rvatures in single-axisrotation. Low production rates.

An extruded parison tube of heated therm oplastic ispositioned between two halves of an open split moldand expanded against the sides of the closed mold viaair pressure. The mold is opened and the part ejected.Low tool and die costs, rapid production rates, andability to mold fairly complex hollow shapes inone piece.Dough-consistent thermoplastic mass is formed into asheet of uniform thickness by passing it through andover a series of heated or cooled rolls. Calenders arealso utilized to apply plastic covering to the backs ofother materials. Low cost, and sheet materials arevirtually free of molded-in stresses.Liquid plastic which is generally thermoset exceptfor acrylics is poured into a m old w ithout presssure,cured, and taken from the mold. Cast thermoplasticfilms are produced via building u p the m aterial (eitherin solution o r hot-melt form) against a highly polishedsupporting surface. Low mold cost, capability to formlarge parts with thick cross sections, good surfacefinish, and convenient for low-volume production.Reinforcement is placed in mold and is rotated. Resindistributed through pipe; impregnates reinforcementthrough centrifugal action. Utilized for round objects,particularly pipe.

Blow

Calendering

Casting

Centrifugal casting


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Table 1.3 Cont inuedLimi ta t ionsescriptionrocess

Economics generally depends on closetolerance control.

When compared to process such as injectiomo lding it is limited to relatively simpleshapes, and few materials can be processedin this manner.

Extremely intricate parts containingundercuts, side draws, small holes, delicatinserts, etc.; very close tolerances aredifficult to produce.

Process methods vary. Both thermoplastics andthermosets wid ely used in coating of numerousmaterials. Roller coating similar to calendering process.Spread coating employs blade in front of roller toposition resin on material. Coatings also applied viabrushing, spraying, and dipping.Similar to compression m olding in tha t material ischarged into a split mold; it differs in that it employsno heat, only pressure. Part cure takes place in anoven in a separate operation. Some thermoplasticbillets and sheet ma terial are cold formed in aprocess similar to drop-hammer die forming or fastcold-form stamping of metals. Low -cost ma tched-toolmolding s exist w hich utilize a rapid exotherm to curem olding s on a relatively rapid cycle. P lastic or concretetooling can be used. With process comes ability toform heavy or tough-to-mold materials; simple,inexpensive, a nd often has rapid production rate.Principally polymerized thermoset compound, usuallypreformed, is positioned in a heated mold cavity; themold is closed (heat and pressure are applied) and thematerialflowsand fills th e mold cavity. Heat completespolymerization and the part is ejected. The processis sometimes used fo r thermo plastics, e.g. vinylphonog raph records. Little material waste is attainable;large, bulky pa rts can be m olded; process is ad aptableto rapid automation (racetrack techniques, etc.).

Coating

Cold pressure molding

Compression molding


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Low-volume process subject to inherentlimitations on materials which can leadto product defect caused by exotherm,curing or molding conditions, lo wthermal conductivity, high thermalexpansion, and internal stresses.Usually limited to sections of uniform crossection.

Limited to shapes of positive curvature;openings and holes can reduce strengthif not properly designed into moldingoperations.

Mixed compound is poured into open molds tosurround and envelope components; cure may be atroom temperature with heated postcure. Encapsulationgenerally includes several processes such as potting,embedding and conformal coating.Widely used fo r continuous production of film, sheet,tube, and other profiles; also used in conjunction withblow molding. Thermoplastic or thermoset moldingcompound is fed from a hopper to a screw and barrelwhere it is heated to plasticity then forwarded, usuallyvia a rotating screw, through a nozzle possessing th edesired cross section. Production lines require input andtakeoff equipment that can be complex. Low tool cost,numerous complex profile shapes possible, very rapidproduction rates, can apply coatings or jacketing to corematerials (such as wire).Excellent strength-to-weight. Continuous, reinforcedfilaments, usually glass, in the form of roving aresaturated with resin and machine-wound ontomandrels having shape of desired finished part. Oncewinding is completed, part and mandrel are cured;mandrel can then be removed through porthole at endof wound part. High-strength reinforcements can beoriented precisely in direction where strength isrequired. Good uniformity of resin distribution infinished part; mainly circular objects such as pressurebottles, pipes, and rocket cases.

Encapsulation

Extrusion molding

Filament winding


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Table 1.3 Cont inuedLimi tat ionsescriptionrocess

High initial tool and die costs; noteconomically practical fo r small runs.

High tool and die costs. Limited to simpleshapes and cross sections.

Prevalent high mold and equipment costs.Parts often require extensive surfacefinishing.

Very widely used. High automation of manufacturingis standard practice. Thermoplastic or thermoset isheated to plasticity in cylinder at controlledtemperature, then forced under pressure through anozzle into sprues, runners, gates, and cavities ofmold. The resin undergoes solidification rapidly,th e mold is opened, and the part ejected. Injectionmolding is growing in the making of glass-reinforcedparts. High production runs, low labor costs, highreproducibility of complex details, and excellentsurface finish.Material , usually in form of reinforcing cloth,paper, foil, metal, wood, glass fiber, plastic, etc.,preimpregnated or coated with thermoset resin(sometimes a thermoplastic) is molded under pressuregreater than lO O O ps i (7MPa) into sheet, rod, tube, orother simple shapes. Excellent dimensional stabilityoffinished product; very economical in large productionof parts.A variation of the conventional compression moldingthis process employs two metal molds possessing aclose-fitting, telescoping area to seal in the plasticcompound being molded and to allow trim of thereinforcement. The mat or preform reinforcement ispositioned in the mold and the mold is closed andheated under pressures of 150-400psi (1-3MPa).The mold is then opened and the part is removed.

Injection molding

Laminating

Matched-die molding


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Close tolerance co ntrol requ ires diligence.Unidirectional strength usually the rule.

Limited to hollow parts; production ratesare usually slow.

Limited to hollow parts; production ratesare very slow; and limited choice ofmaterials that can be processed.

Limited to parts of simple configuration,high scrap, and limited number of materialfrom which to choose.

This process is similar to profile extrusion, but it doesnot provide flexibility and uniformity of productcontrol, and automation. Used for continuousproduction of simple shapes (rods, tubes, and angles)principally incorporating fiberglass or otherreinforcement. High output possible.A predetermined amount of powdered or liquidthermoplastic or thermoset m aterial is poured intomold; mold is closed, heated, and rotated in the axisof tw o planes until contents ha ve fused to inner w allsof mold; mold is then opened and part is removed.Low mold cost, large hollow parts in one piece can beproduced, and molded parts are essentially isotropicin nature.Pow dered or liquid thermo plastic m aterial ispoured into a mold to capacity; mold is closed andheated for a predetermined time in order to achieve aspecified buildup of partially cured material on moldw alls; mold is opened and unpolymerized material ispoured out; and semifused part is removed from moldand fully polymerized in oven. Low mold costs andeconomical for small production runs.Heat-softened thermoplastic sheet is positioned overmale or female mold; air is evacuated from betweensheet and mold, forcing sheet to conform to contour

Pultrusion

Rotational molding

Slush molding

Thermoforming


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Table 1.3 Cont inuedLimi tat ionsescriptionrocess

High mold cost; high material loss in spruand runners; size of parts is somew hatlimited.

Not economical for large-volumeproduction; uniformity of resindistribution difficult to control; only onegood surface; limited to simple shapes.

of mold. Variations are vacuum snapback, plug assist,drape forming, etc. Tooling costs are generally low,large part production with thin sections possible,and often comes out economical fo r limitedpart production.Related to compression and injection moldingprocesses. Thermoset molding compound is fed fromhopper into a transfer chamber where it is then heatedto plasticity; it is then fed by a plunger through sprues,runners, and gates into a closed mold where it cures;mold is opened and part ejected. Good dimensionalaccuracy, rapid production rate, and very intricateparts can be produced.Several layers, consisting of a mixture of reinforcement(generally glass cloth) and thermosetting resin arepositioned in mold and roller contoured to mold'sshape; assembly is usually oven-cured without theapplication of pressure. In spray molding, amodification, resin systems and chopped fiber aresprayed simultaneously from a spray gun against th emold surface. Wet-layup parts are sometimes curedunder pressure, using vacuum bag, pressure bag, orautoclave, and depending on the method employed,wet-layup can be called open molding, hand layup,sprayup, vacuum bag, pressure bag, or autoclavemolding. Little equipment required, efficient, lo w cost,and suitable fo r low - volum e production of parts.

Transfer molding

Wet-layup or contactmolding


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the parts must be coined, formed, machined, or rapidly cooled.Occasionally, however, this memory or instability can be usedadvantageously.

Most plastic parts can be produced with a built-in memory. That is,their tendency to move into a new shape is included as an integral part ofthe design. So after the parts are assembled in place, a small amount ofheat can coax them to change shape. Plastic parts can be deformed duringassembly then allowed to return to their original shape. In this case theparts can be stretched around obstacles or made to conform to unavoid-able irregularities without their suffering permanent damage.

The time- and temperature-dependent change in mechanical propertiesresults from stress relaxation and other viscoelastic phenomena that aretypical of polymers. When the change is an unwanted limitation, it iscalled creep. When the change is skillfully adapted to use in the overalldesign it is called plastic memory.Potential memory exists in all thermoplastics. Polyolefins, neoprenes,silicones and other cross-linkable polymers can be given memory eitherby radiation or by chemical curing. Fluorocarbons, however, need no suchcuring. When this phenomenon of memory is applied to fluorocarbonssuch as TFE, FEP, ETFE, ECTFE, CTFE, and PVF2, interesting high-temperature or wear-resistant applications become possible.Drying plasticsThere is much more to drying resins for processes such as injectionmolding, extrusion, and blow molding than blowing 'hot air' into a hop-per. Effects of excessive moisture cause degradation of the melt viscosityand in turn can lead to surface defects, production rejects, and even failureof parts in service (Table 1.4). First one determines from a supplier, or


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Decrease material temperature by lowering cylindertemperature, decrease screw speed/lower backpressure (screw machine)Decrease overall cycle timeDecrease plunger forward timeCheck resin data sheet for meltdown temperatureM ake sure operators know correct process temperatureset pointClean or replace filters3Dry cycle machine fo r several complete cycles. (This iscommon with equipment which is not operated on acontinual basis)Replace with larger hopperbAdd 'after-cooler' to return air lineReplaceReplaceAdjust or replaceAdjustReplace0

Material temperature too high

Cycle time too longPlunger pushing forwardtoo longProcess temperature settoo highDirty process/auxiliary filter(s)Desicant saturated

Material residence time inhopper too shortReturn air temperaturetoo highHeaters burned outBad heater thermostat orthermocoupleCycle timer malfunctioningAir control valves not seatingproperlyContaminated or wornoutdesiccant

Material in drying hoppercaking or meltdownoccurringDew point reading too high


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Table 1.4 Cont inuedSolutionsossible causesy mpt om

Check and correct rotationCheck electrical connections; replace elements if neededIf valve system, check and repair valve /drive assemblyIf rotational system, adjust drive-assembly. Check electricaconnections on motor and replace motor if neededCheck hopper lid, all hose connections, hoses and filters.Tighten, replace, repair as neededCheck meter and recalibrateCheck electrical connections o n heaters /controller. Repairreplace0Reset fo r correct tempera tureSecure thermocouple probe into coupling at inlet of hoppeCheck electrical connections and replace if necessaryInsulate hopper and hopper inlet air lineSee Insufficient airflow 7Adjust or replaceCleanReset fo r correct temperatureCheck electrical connections. Replace /repair if neededCheck electrical connectionsReplace /repair if needed

Incorrect blow er rota tionRegeneration heatingelements inoperativeDesiccant assembly nottransferringMoist room air leading intodry process airDew point m eter incorrectElectrical malfunctionsDesiccant bed(s) contaminatedIncorrect temp erature settingThermocouple not properlylocatedElectrical malfunctionsInsufficient reactivationairflowMalfunctioning cycle timeBlades of blower wheel dirtyIncorrect temperature settingon con trollerController m alfunc tioningProcess heating elements

Dew point cycling fromhigh to lowProcess air temperaturetoo high

Excessive changeovertemperature

Process air temperaturetoo low


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Replace or repairCheck supply voltageCheck /clean filters, check blower rotation and correct,check and repair airflow meterCheck connections. Delivery hose should enter hopperat bottomInsulate hopper and hopper inlet air lineReplace w ith high temperature dryer

Clean or replace3Check manufacturer 's electrical instructions, and changeblower rotationRemove obstructionDisengage line exiting dryer repair if neededReplace desiccant0Increase hop per size or drain hopper and refillRelocate dryer, reduce vibrationReduce voltage, relocate dryer, or use heaters rated foractual voltageAdjust or replaceClean

Thermostat m alfunctionVoltage differentialsInadequate airflowHose connections incorrectInadequate insulationDryer inadequate for requiredtemperaturesProcess or auxiliary filter(s)blockedBlower rotation incorrectAir ducts blockedAirflow meter incorrectDesiccant bed contaminatedTightly packed material inhopperExcessive vibrationHigh voltage conditionMalfunction in heaterthermostatBlades on blow er w heel dirty

Insufficient airflow(Dew point reading could begood but resin is still wet)

Heater burn out

a An inexpensive pressure-differential switch, common option f o r almost every brand of dehumidifying dryer, will signal when a filter is restricairflow.b Since drying systems tend to be designed for a specific material, different materials may need longer residence times or higher drying temperatuc Plastic dust contaminants, because of their flash point, can ignite during regeneration of the desiccant bed causing a fire inside the dehumidi


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processed when using a desiccant dryer. The pressure drop through thebed should be less than 1 mm H2O per millimeter of bed height.Simple tray dryers or mechanical convection, hot-air dryers, while ad-equate fo r some resins, are simply incapable of removing enough waterfo r proper processing of hygroscopic resins, particularly during periodsofhigh ambient humidity. The most effective and efficient drying system forthese resins incorporates an air-dehumidifying system in the materialstorage/handling network. Consistently and adequately it has toprovidemoisture-free air in order to dry the 'wet' resin.Initially expensive, it does give improved production rates and helps toachieve zero defects. There are several manufacturersand systems fromwhich to choose. All the systems are designed to accomplish the same endresults, but the approaches to regeneration of the desiccant beds vary.Hygroscopic resins are commonly passed through dehumidifying hop-per dryers before they enter a screw plasticator. However, except whereextremely expensive protective measures are taken, the drying may beinadequate, or the moisture regain may be too rapid to avoid productdefects unless barrel venting is provided (Chapters 2 and 3 review vent-ing). To ensure proper drying for 'delicate' parts such as lenses, someplants use drying prior to entry into the barrel as well as venting. Al-though it is much less hygroscopic than th e usual resin (ABS, PC, etc.), PStoo is usually vented during processing toprotect against surface defects.The effect of having excess moisture manifests itself in various ways,depending on the process being employed. The common result is a loss inmechanical properties (Fig. 1.9) and physical properties, with splays, noz-zle drool between shot-size control, sinks, and other losses that may occurduring processing. The effects during extrusion can also include gels,


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trails of gas bubbles in the extrudate, arrowheads, waveforms, surging,lack of size control, and poor appearance.

Air entrapmentAir entrapment is a common problem in most processes. With screwplasticators (injection, extrusion, blow molding) it is caused by air beingtaken in with plastics from the feedhopper. Compression of the solidmaterial in the screw feed section (Chapter 2) will normally force air outof the 'solid' melt bed. However, there are times that the air cannot exitback to the hopper. Thus, it moves forward with the melt until it exitsfrom the mold or die. These air pockets can cause problems such asinclusions or surface imperfections.

There are solutions to this situation. The more popular and simpleapproach is to change the temperature in the solids-conveying zone toachieve a more positive compacting of the solid bed. Often a temperatureincrease of the first barrel section reduces the air entrapment; however, alower temperature sometimes gives an improvement. In any case, thetemperatures in the solids-conveying zone are important parameters forair entrapment. The barrel and screw temperatures are both important.The next step is an increase in the mold or diehead pressure to alter thepressure profile and hopefully to achieve a more rapid compacting of thesolid bed. Another possible solution is to starve-feed the extruder, but thiswill probably reduce the output and requires additional hardware suchas, an accurate feeding device.

If the problem still exists, a change in plastic particle size or shape couldhelp. Other options include a vacuum hopper system (rather complex andexpensive), a grooved barrel section (rapid compaction occurs), reducedfriction on the screw (applying a coating), and increased compression


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Plastics most frequently needing RAs include polyurethanes, polyesters(TPs and TSs), polyolefins, polycarbonates and epoxies.

RAs come in a wide variety of forms and modes of application. Bothneat liquids and solvent solutions, as well as solids such as powders andflakes, compounded mixtures and pastes, emulsions, dispersions, pre-formed films, in situ film formers, and integral migratory additives areavailable. Many formulated products serve more than one processingfunction and contain other additives, such as antioxidants. Combinedlubricant-stabilizer packages are often used with polyvinyl chloride. Theexternal treatment types can be applied by any of the standard coatingmethods, including brushing, dipping, dusting, spraying, electrostaticcoating, and plasma arc coating.

Despite the diversity of products, RAs have some features in common,notably inertness to at least one of the surfaces in question at the tempera-ture of the release process and low surface tension. Low surface tension isimportant in obtaining good wetting of a mold. It is also a reflection of thelow intermolecular forces desirable in effective release compositions. Notsurprisingly, inertness and weak cohesion are the opposite of good adhe-sive properties.

The release agent should be chosen with subsequent events in mind,as well as for ease of release and stability. In addition to ease of release,other selection criteria include prevention of buildup; mold cleanability;compatibility with secondary operations such as painting, plating, andultrasonic welding; mold compatibility; type and time available for appli-cation; health and safety requirements and cost. As an example, whenusing silicone as an RA, it becomes difficult or impossible to paint on it orto attach it adhesively.

Heat history, residence time, andrecycling


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Heat profileTo obtain the best processing melts for any plastics, one starts with theplastic manufacturer's recommended heat profile and/or one's own expe-rience. These are starting points for various types of plastics, as shownin Fig. 1.10 and Table 1.5. The time and effort spent on startup make itpossible to achieve maximumefficiency of performance versus cost for theprocessed plastics. By the application of logic, the information gained canbe stored and applied to future setups. In all probability, similar machines(even from the same manufacturer) will not permit duplication of a pro-cess, but knowledge thus gained will guide the processor in future setups.

An amorphous material usually requires a fairly low initial heat in ascrew plasticator; its purpose is to preheat material but not melt it in thefeed section before it enters the compression zone of the screw. On theother hand, crystalline material requires higher initial heating to ensurethat it melts before reaching the compression zone; otherwise satisfactorymelting will not occur. Careful implementation of these procedures pro-duces the best melt, which in turn produces the best part. (Filled plastics,particularly those with thermally conductive fillers, usually require differ-ent heat profiles, i.e., a reverse profile where the area of the feed throat isbetter than the front zone.)

E x a m p l e o f a ThermosetProcessing Heat-Time Profile Cycle

a . S t a r t o f p r o c e s smperature


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Table 1.5 Melt processing temperatures for TPsaProcess ing temperature ra te

Mater ial 0C 0FABS 180-240 356-464Acetal 185-225 365-437Acrylic 180-250 356-482Nylon 260-290 500-554Polycarbonate 280-310 536-590LDPE 160-240 320-464H O P E 200-280 392-536Polypropylene 200-300 392-572Polystyrene 180-260 356-500PVC, rigid 160-180 320-365a Values are typical f o r injection molding and most extrusionoperations. Extrusion coating is done at higher temperatures(i.e., about 60O 0F for LDPE). See the appendix for metricconversion charts (pag e 642).

Processing andtolerancesProcessing is extremely important for tolerance control, sometimes it isthe most influential factor. The dimensional accuracy of the finished partrelates to the process, the accuracy of mold or die production, and theprocess controls, as well as the shrinkage behavior of the plastic. Chang-ing the dimensions of a mold or a die can cause wear to arise duringproduction; this should always be taken into account.

The mold or die is one of the most important pieces of production


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Table 1.6 Guidelines for wall thicknesses of TS molding materials

Alkyd, glass filledAlkyd, mineral filledDially phthalateEpoxy, glass filledMelamine, cellulose filledUrea, cellulose filledPhenolic, g eneral purposePhenolic, flock filledPhenolic, glass filledPhenolic, fabric filledPhenolic, mineral filledSilicone glassPolyester prem ix

M i n i m u mth ickness ,in . (mm)

0.040 (1.0)0.040 (1.0)0.040 (1.0)0.030 (0.76)0.035 (0.89)0.035 (0.89)0.050 (1.3)0.050 (1.3)0.030 (0.76)0.062 (1.6)0.125 (3.2)0.050 (1.3)0.040 (1.0)

Averagethickness ,in . ( m m )

0.125 (3.2)0.187 (4.7)0.187 (4.7)0.125 (3.2)0.100 (2.5)0.100 (2.5)0.125 (3.2)0.125 (3.2)0.093 (2.4)0.187 (4.7)0.187 (4.7)0.125 (3.2)0.070 (1.8)

M a x i m u mth ickness ,in . (mm)

0.500 (13)0.375 (9.5)0.375 (9.5)1.000 (25.4)0.187 (4.7)0.187 (4.7)1.000 (25.4)1.000 (25.4)0.750 (19)0.375 (9.5)1.000 (25.4)0.250 (6.4)1.000(25.4)

Table 1.7 Guidelines for wal l thicknesses of TP molding materials

AcetalABSAcrylicCellulosics

M i n i m u m ,in . ( m m )0.015 (0.38)0.030 (0.76)0.025 (0.63)0.025 (0.63)

Avera ge ,in . (mm)0.062 (1.6)0.090 (2.3)0.093 (2.4)0.075 (1.9)

M a x i m u m ,in . (mm)0.125 (3.2)0.125 (3.2)0.250 (6.4)0.187 (4.7)


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Table 1.8 Guide to tolerances of TP extrusion profiles

Wall thickness (%)Angle ( )

Profile dimensions


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Table 1.9 Parameters that influence part tolerancePart design

MaterialMold design

Machine capability

Molding cycle

Part configuration (size/shape). Relate shape to flow ofmelt in mold to meet performance requirements thatshould at least include tolerances.Chemical structure, molecular weight, amount and typeof fillers/additives, heat history, storage, handling.Number of cavities, layout and size of cavities/runners/gates/cooling lines/side actions/knockout pins/etc.Relate layout to maximize proper performance of meltand cooling flow patterns to meet part performancerequirements; pre-engineer design to minimize wearand deformation of mold (useproper steels); lay outcooling lines to meet temperature-to-time coolingrate of plastics (particularly crystalline types).Accuracy and repeatability of temperature, time, velocity,and pressure controls of injection unit, accuracy andrepeatability of clamping force, flatness and parallelismof platens, even distribution of clamping on all tie-rods,repeatability of controlling pressure and temperatureof oil, oil temperature variation minimized, no oilcontamination (by the time you see oil contamination,damage to the hydraulic system could have alreadyoccurred), machine properly leveled.Set up the complete molding cycle to repeatedly meetperformance requirements at the lowest cost byinterrelating material, machine and mold controls.

though that may extend the cycle time, or heat-treat according to the resinsupplier's suggestions.


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fillers. Compared to the TPs, the TSsgenerally have more filler. The typeand amount of filler, such as its reinforcement, can significantly reduceshrinkage and tolerances.

I n s p e c t i o nInspection variations are often the most critical and most overlookedaspect of the tolerance of a fabricated part. Designers and processors basetheir development decisions on inspection readings, but they rarely deter-mine the tolerances associated with these readings. The inspection varia-tions may themselves be greater than the tolerances for thecharacteristicsbeing measured, but this can go unnoticed without a study of the inspec-tion method capability.

Inspection tolerance can be divided into two major components: theaccuracy variability of the instruction and the repeatability of the meas-uring method. The calibration and accuracy of the instrument aredocumented and certified by its manufacturer, and the instrument isperiodically checked. Understanding the overall inspection process is ex-tremely useful in selecting the proper method for measuring a specificdimension. When all the inspection methods available provide an accept-able level of accuracy, the most economical method should be used.As the overall fabricating tolerance is analyzed into the sources of itsvariation components, the potential advantage of analytical programscomes into play with their ability to process all these factors efficiently. Allthe empirical tolerance ranges for each tooling method and inspectionmethod are stored in data files for easy retrieval. For each critical dimen-sion the program sums all the component tolerances and computes a overall tolerance for each critical dimension. The program then providesa tabulated estimate of the achievable processing tolerances and pinpoints


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Intelligent processingTo remain competitive on a worldwide basis, processors must continue toimprove productivity and product quality. What is needed is a way to cutineffciency and the costs associated with it. One approach that promises toovercome these difficulties is called intelligent processing of materials.This technology utilizes new sensors, expert systems, and process modelsthat control processing conditions as materials are produced, without theneed for human control or monitoring.

Sensors and expert systems are not new in themselves. What is novel isthe manner in which they are tied together. In intelligent processing, newnondestructive evaluation sensors are used to monitor the developmentof a material's microstructure as it evolves during production in real time.These sensors can indicate whether the microstructure is developingproperly. Poor microstructure will lead to defects in materials. In essence,the sensors are inspecting the material online, before the end product isproduced.

Next, the information these sensors gather is communicated, along withdata from conventional sensors that monitor temperature, pressure, andother variables, to a computerized decision-making system. This decisionmaker includes an expert system and a mathematical model of the pro-cess. The system then makes any changes necessary in the productionprocess to ensure the material's structure is forming properly. Thesemight include changing temperature or pressure, or altering other vari-ables that will lead to a defect-free end product.

There are several significant benefits that can be derived from intelli-gent processing. There is a marked improvement in overall productquality and a reduction in the number of rejected products. And theautomation concept that is behind intelligent processing is consistent withthe broad, systematic approaches to planning and implementation being


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F l a s h a r e a

M o l d i n ga r e aRampreure

S h o r t s h o t a r e a

M o l d t e m p e r a t u r eFigure 1.11 Two-dimensional molding area diagram ( M A D ) that plots injectionmolding ram pressure versus mold temperature.

machine and/or control manuals. Once the machine is operating, theprocessor methodically makes one change at a time to determine theresult. Two basic examples are presented to show a logical approach toevaluating changes made with any processing machine. As the injectionmolding machine is very complex with the all controls required to set itup, these examples refer to the injection molding process.

Figure 1.11 shows what happens when changing mold temperature and


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Rampreureps

Figure 1.12 Three-dimensional molding volume diagram (MVD) that plots melttemperature, mold temperature, and ram pressure.different shapes developed for a TP and a TS, the approach is similar forboth.

The second example is the use of a three-dimensional diagram (Fig.1.12). This molding volume diagram (MVD) compares the behavior of athermoplastic in the mold based on varying melt temperature, mold tem-perature, and ram pressure. Thus all parts molded within the volumeproduce good parts. To operate with maximum efficiency, one should


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P A R T T O B E F O R M E D

S M A L L P A R TL E S S T H A N 1 t q f tL E S S T H A N 5 Ib

L E S S T H A N 2 5 0 FT H E R M O P L A S T I C SO V E R 2 S O0 FT H E R M O S E T SU N D E R 2 5 O

0 FT H E R M O P L A S T I C S

L A R G E P A R TO V E R 1 s q f tO V E R 5 lb s

O V E R 2 5 O 0 FT H E R M O S E T S

L O W V O L U M EIIG H V O L U M EO W V O L U M EIG H V O L U M E IO N G L E N G T H S IA R G E A R E A IM A C H I N ET H E R M O F O R MC O M P R E S S I O NC A S T I N GR O T O F O R MF O A MA D H E S I V E B O N D

I N J E C T I O NB L O W M O L DT H E R M O F O R ME X T R U S I O NR O T O F O R MR IM

C A S T I N GM A C H I N I N GL O W P R E S S U R EL A Y U PP O S T F O R MS P R A Y U PR E S I N T R A N S F E R

C O M P R E S S I O NT R A N S F E RI N J E C T I O NL A M I N A T I O NP U L T R U S I O N

E X T R U D EH E R M O F O R MF O A MH E A T S E A LW E L DR O T O F O R MB L O W M O L DA D H E S I V E B O N DS T R U C T U R A LF O A MR IM

L O W - P R E S S U R EL A M I N A T I O NF I L A M E N T W t N D I N GC O M P R E S S I O NH I G H - P R E S S U R EL A M I N A T I O NP O S T F O R MA D H E S I V E B O N DM A C H I N EP U L T R U S I O N

Figure 1.13 Guide to process selection.

T O O L T O B E M A D E


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P R O C E S S E S

C A S T I N GO T O F O R MH E R M OF O R M I N GO M P & T R A N S .L O W M O L D I N GX T R U -S I O NN J E C T I O NE L E C T R O F O R M E DO V O LI V O LO,O V O LI V O LO V O LI V O LI V O LI V O L L O W V O L S P R A Y M E T A L

D I P P E D M E T A LS I L I C O N E

P L A S T I CE L A S T O M E R D I P M E T A

E N C A P

P L A S T I C( T P O R T SE L A S T O M E

R E I N / FP L A S T I C SP L A S T I C

A LW O O DS T E E L

E L E C T R O F O R MS P R A Y E DM E T A L

E L A S T O M E R

S H E E TM E T A LA S T A LE L E C T R O F O R M

W O O DP L A S T E R

A LA LE L E C T R O F O R M& B A C K - U P

F I L L E DE P O X YF O A MP R O C E S S( N O T S T R U C T )

P L A S T E RA L

P L A S T I CE L E C T R O F O R M

S P R A Y E DM E T A L

S T E E L( M A C HH O B B E D )A L

P L A S T E RE P O X Y -F I B E R G L A S

F I L L E DE P O X Y

A LB C u

E L E C T R O F O R M& B A C K U P

S T E E L

R IMS T E E L

C A S T A LM E H A N I T E

F I L L E DE P O X Y

C A S T A LM A C H . A L

K I R K S I T EF I L L E DE P O X Y

S T E E LM A C H I N EH O B B E DE L E C T R OF O R M &B A C K - U P

Figure 1.14 Gu ide to tool selection.


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Table 1.10 Molding process guide to plastic materials3

Rota-t i o n a ll o wD ipa n dslushF i l a -ment

RPmoldingF R PS h e e tf o r m i n gL a m i -natingExtru-sionStruc-t u r a lf o a mo a t i n gC o l dmoldingastingT r a n s -f e rC o m p r e s -s i o nI n j e c -t i o nM a t e r i a lf a m i l y

X

XX

X

XX

XXX

X

X

XXX

X

X

XXXXXX

X

XXXXX

X

XXXXXX

X

XXXXX

XX

XX

X

X

XXXXXXXX

X

X

XX

X

XX

XXXX

X

XXX

XX

X

X

XXX

XX

X

XXXXXXXXXXXXXX

ABSAcetalAcrylicA U y IASACellulosicEpoxyFluoroplasticMelamine-

formaldehydeNylonPhenol-formaldehydePoly(amide-imide)PolyaryletherPolybutadienePolycarbonatePolyester (TP)


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Polyester-fiberglass (TS)PolyethylenePolyimidePolyphenyleneoxidePolyphenylenesulfidePolypropylenePolystyrenePolysulfonePolyurethane(TS) (TP)SANSiliconeStyrene-

butadieneUrea-formaldehydeVinyla Compounding permits using other processes.


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Table 1.11 Guide to compatibility of processes and materialsThermose t s Thermoplast ics

Pye

PyeSMC

PyeBMC

E Pyueh

AaNo6

No66

Pyabe

Pyoen

Pynensulde

A Pynenod

Pyyen

PyeP

PyeP

InjectionmoldingHand layupSprayupCompressionmoldingPreformmoldingFilamentwindingPultrusionResin transfermoldingReinforcedreactioninjectionmolding

Table 1.12 General information relating processes and materials to properties ofplastics


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Thermose t sPolyestersProperties shownalso apply tosome polyestersformulated forthermoplastic

processing byinjection molding

Epoxies

Phenolics

Silicones

Propert iesSimplest, most versatile,economical and most widelyused family of resins, havinggood electrical properties,good chemical resistance,especially to acids

Excellent mechanicalproperties, dimensionalstability, chemical resistance(especially alkalis), lo w waterabsorption, self-extinguishing(when halogenated), lowshrinkage, good abrasionresistance, very goodadhesion propertiesGood acid resistance, goodelectrical properties(except arc resistance), highheat resistanceHighest heat resistance, lowwater absorption, excellentdielectric properties, high arcresistance

ProcessesCompression moldingFilament windingHand layupM at moldingPressure bag moldingContinuous pultrusionInjection moldingSprayupCentrifugal castingCold moldingComoform 3EncapsulationCompression moldingFilament windingHand layupContinuous pultrusionEncapsulationCentrifugal casting

Compression moldingContinuous laminating

Compression moldingInjection moldingEncapsulation

Table 1.12 C on t in ued


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Thermose t sStyrene-acrylonitrileAcrylics

Vinyls

Acetals

Polyethylene

Fluorocarbons

Polyphenyleneoxide,modified

Propert iesGood solvent resistance,good long-term strength,good appearanceGood gloss, weather resistance,optical clarity, and color;excellent electrical propertiesExcellent weatherability,superior electrical properties,excellent moisture andchemical resistance, self-extinguishingVery high tensile strengthand stiffness, exceptionaldimensional stability, highchemical and abrasionresistance, no known roomtemperature solventGood toughness, light weight,how cost, good flexibility,good chemical resistance;can be 'welded'Very high heat and chemicalresistance, nonburning,lowest coefficient of friction,high dimensional stabilityVery tough engineering plastic,superior dimensional stability,low moisture absorption,excellent chemical resistance

ProcessesInjection molding

Injection moldingVacuum formingCompression moldingContinuous laminatingInjection moldingContinuous laminatingRotational molding

Injection molding

Injection moldingRotational moldingBlow moldingInjection moldingEncapsulationContinuous pultrusionInjection molding


45/48

a


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Table 1.13 Specific processing method s as a function of part designVarying

cross sectiGood f in i sh ,

both sideseldableSlides/cores

B oxsections

Sphericalshape

Verticalwallsonesib srocess

Thermoplastics

Thermosets

InjectionInjection compressionHollow injectionFoam injectionSandwich moldingCompressionStampingExtrusionBlow moldingTwin-sheet formingTwin-sheet stampingThermoformingFilament windingRotational casting

CompressionPowderSheet molding compoundCold-press moldingHot-press molding


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Y

NNNYYYNYYYYYYY

High-strength sheetmolding compoundPrepregVacuum bagHand layupInjectionPowderBulk molding compoundZM CStampingReaction injection moldingResin transfer molding, orresinjectHigh-speed resin transfermolding, or fast resinject

Foam polyurethaneReinforced foamFilament windingPultrusiona Y = yes; N = no; N / A = not applicable.


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Table 1.14 Basic processing methods as a function of part designW e t l a( c o n t am o l d i nT r a n s f e rc o m p r e s s i o nT h e r m o -f o r m i n go t a t i o n a lM a t c h e d d i em o l d i n gn j e c t i o nF i l a m e n tw i n d i n gx t r u s i o no m p r e s s i o na s t i n gB l o wm o l d i n ga r t d e s i g n

M o l d ai n o np l a nM o l d s0 .5( 1 2 . 70 . 2 5( 6 . 4 )O0 . 0 6( 1 . 5 )N oY e sY e sY e sY e sY e sY e sY e s4 - 50 . 0 2

S i m p l ec o n f i g u r a t i o n sE q u i p m e n t6( 1 5 0 )0 . 0 1 - 0 . 1 2 5( 0 . 2 5 - 3 . 1 8 )10 . 0 1 - 0 . 1 2 5( 0 . 2 5 - 3 . 1 8 )Y e sN R bY e s

Y e sY e sY e sY e sY e s1 -2

0 . 0 0 1

M o l d a b l ei n o n ep l a n eM a t e r i a l3( 7 6 )0 . 1 2 5( 3 . 1 8 )10 . 0 0 2( 0 . 0 5 )N oY e s aN R bY e sN oY e sY e sY e s1-30 . 0 1

H o l l o wb o d i e sM a t e r i a l0 .5( 1 2 . 7 )0 . 0 1 - 0 . 1 2 5( 0 . 2 5 - 3 . 1 8 )10 . 0 2( 0 . 5 )Y e sY e s cY e s

Y e sY e sY e sY e sY e s2 -30 . 0 1

M o l d a b l ei n o n ep l a n eE q u i p m e n t2( 5 1 )0 . 0 6( 1 . 5 )10 . 0 3( 0 . 8 )N oN R bY e sY e sY e sY e sN o fY e s4 -5

0 . 0 0 5

F e wl i m i t at i o n sE q u i p m e n t6( 1 5 0 )0 . 0 1 - 0 . 1 2 5( 0 . 2 5 - 3 . 1 8 )< 10 . 0 0 5( 0 . 1 )Y e sY e s aY e s

Y e sY e sY e sY e sY e s1

0 . 0 0 1

S t r u c t u r ew i t h s u r f a c e so f r e v o l u t i o nE q u i p m e n t3( 7 6 )0 . 1 2 5( 3 . 1 8 )2 -30 . 0 1 5( 0 . 3 8 )N oN R "Y e sY e sY e sN oN o eN o

50 . 0 0 5

C o n s t a n tc r o s s s e c t i o np r o f i l eM a t e r i a l6( 1 5 0 )0 . 0 1 - 0 . 1 2 5( 0 . 2 5 - 3 . 1 8 )N R b0 . 0 0 1( 0 . 0 2 )N oY e sY e sY e sY e s dY e sY e sN o1 -2

0 . 0 0 5

M o l d a b l ei n o n ep l a n eE q u i p m e n t0 .5( 1 2 . 7 )0 . 1 2 5( 3 . 1 8 )> 10 . 0 1 - 0 . 1 2 5( 0 . 2 5 - 3 . 1 8 )Y e sN R bY e sN oY e sY e sY e sY e s1 -2

0 . 0 0 1

S i m p l ec o n f i g u r a t i o n sM a t e r i a lN o n e

0 . 0 1 - 0 . 1 2 5( 0 . 2 5 - 3 . 1 8 )0 -10 . 0 1 - 0 . 1 2 5( 0 . 2 5 - 3 . 1 8 )Y e sY e s aY e sY e sY e sY e sY e sY e s

20 . 0 0 1

H o l l o wb o d i e sM a t e r i a l> 0 . 2 5( 6 . 4 )0 . 1 2 5( 3 . 1 8 )

O0 . 0 1( 0 . 2 5 )Y e sY e sY e sY e sY e sY e sY e sY e s1 -20 . 0 1

M a j o r s h a p ec h a r a c t e r i s t i c sL i m i t i n g s i z e f a c t o rM a x . t h i c k n e s s , i n .( m m )M i n . i n s i d e r a d i u s , i n .( m m )M i n . d r a f t ( d e g . )M i n . t h i c k n e s s , i n .( m m )T h r e a d sU n d e r c u t sI n s e r t sB u i l t- in c o r e sM o l d e d - i n h o l e sB o s s e sF i n s o r r i b sM o l d e d i n d e s i g n sa n d n u m b e r sS u r f a c e f i n i s h 8O v e r a l l d i m e n s i o n a lt o l e r a n c e ( )a S p e c i a l m o l d r e q u i re d .b N o t r e c o m m e n d e d .c O n l y f l e x i b l e m a t e ri a l.d O n l y d i r e c t i o n o f e x t r u s i o n .e P o s s i b l e w i t h s p e c i a l t e c h n i q u e s .f F u s i n g p r e m i x / y e s .g R a t e d 1 t o 5 ( 1 = v e r y s m o o t h . 5 = r o u g h ) . Next Page
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