Plastic Product Material and Process Selection Handbook Part 5 pps

124 Plastic Product Material and Process Selection Handbook Although there are literally thousands of plastics available, usually no single one will exhibit all desired properties in their proper relation- ships. Therefore a compromise among properties, cost, and fabricating process generally determines the material of construction. There is a logical workable elimination approach to the selection of the correct plastic. Examples among the specific properties have been reviewed in this chapter that include chemical resistance (Table 2.12), color, crazing/cracldng, clectric/clectronic, flame rcsistancc, impact, odor/taste, radiation, temperature resistance (Figure 2.7), permeability (Table 2.13), transparency (Figure 2.8 and Table 2.14), weathering (Figure 2.9), moisture, etc. 1-3, 6, 133, 134, 367, 368,426 Figure 2~ Examples of plastic contraction at low temperatures 2 9 Plastic property 125 Table 2+12 Chemical resistance of plastics (courtesy of Plastics FALLO) PLASTIC ~ ,'m_,,.,.',,,,' n [:m !77 i:eoo l.x. ~,~-; IvIATEFllAL ~,] ,0o !," "'I"1"'' 1 =~ " 1 ~ " l ~1 r ~- + : , l~, ~.i_j l ,.i ,7+ i' l.ials 1-4 H 1 2-S -5 I-S S 1 S $ IS 1 i-~ 1 0.22-0.2S L : : - : ' " - i Acrytics 5 5 2 3 5 5 1 3 2 S 4 4-S 5 6 5 $ 02-0.4 _. [ .: _ . J + ' 1 i 2 3-5 + Acry~nltdk)-lutadtlne- 4 5 3-5 5 1 2-4 1 2-4 1-4 6 1-6 5 3-5 I~ 0,t - 0.4 Styien,I (ABS) __ ,+ Ceiluiose AcILilll (C~) 1 2 3 ;2 3 3 4 2 a 3 8 $ L 8 II [1~ S 5 2.7 ; _ , : l i Cellulose Acelllt 4 5 1 1 3 .3 4 1 2 3 S $ 5 $ 5 I 5 5 ~ 1.3-U Proplonitts (CAP) ] ' l ,1 + . { __ : _ . _, . _ _ i Etxizlel , 1 2 1 2 1-2 i3.4 1 1-2 1 2 ,1-3 3-4 4 !4-5 2 3-4 O.01-0.10 _ _ Ethylene Copolym,ls (EVA) c x x t 5 5 S 1 2 1 S 1 S 1> S ' 2 S 0.05- 0.13 (Ethylene-Vinyl Acetates) " " " ~ : _. . + ~I"- l ' ' i Eihykm*lT*trlttu~ 1 1 I ~ I ],,mi, t co~ ~ ] "i 'l 'i '.t ~ 1 1 ~1 1 "l 1 'i ,'l <o.~ ] ;. .I : i t ' 1 1 1 Fliiorlnillld Ethylene Propylenes (FEP) 1 1 " I 1 1 I 1 1 1 1 1 ' 1 1 1 <:0.01 " ltu'thi~176176 t ! ! 1 1 1 1 1 1 1 1 1 1 I 1 1 1 1 <0,03 i _ ~ 1 1 ]1 ] Polychlorotrfltu~ro- 1 3 4 1 : I 1 1 1 1 1 1 :1 1 0.01 -0,10 emyle ICTm ! _ . 1 I [ Polyletrmfluomef.'~y~nel 1 9 1 1 1 1 1 1 I 11 1 1 1 1 t 1 I 1 0 (xm ! + , ~ i 1 i _ + 1 ~ 1 ~ ~ ~ l= i s i s • s i ~ 1 l ~m-l~'+ Mtihlmimls (lled) [ . . L _._ ! l , . 1 4 1 2-4 I-4 2-5 1 2-4 I 1 2-4 !-5 5 3-5 5 1-5 5 0.2 - (I.5 Ntlrtlll (high lltrrhlr Illotl of Ills or SAN) Nytoruz Phtinoltcl (ltlltd) Polyillomerz . ; . j t ,. t 1 1 12 ~ 3! s t 1 1.1 5 t I 2 0.1-2.0 !+ , +i+, t , t i i , . ~. . ~_ t _ ,, , I. 1 2 _ 1 _ ! l+. I continued 126 Plastic Product Material and Process Selection Handbook Table 2.12 continued PLASTIC - ' ' MATERIAL ,., ,-, ,oo ,., ,., ,., =oo ,., i. , : ~. i: . f " =- I+ Polybulylenes (PB) 3 5 1 5 4 6 1 2 1 3 1 3 1 4 1 1 <0.01 - 0.3 9 Polycarbormte= (PC) 5 5 1 1 S 6 1 $ $ 5 ~ I , 1 1 1 1~ t 8 0.15-0.35 .~ _- _ L "i 1 Polyester= (thermoplutlr 2 5 1 3-5 3 5 1 3-4 2 S 3 4-5 2 3.6 :1 3-4 0.04- 0.00 ~! , - ' - __ :_,l, __ Polyestel'l ~l-3 3-5 2 3 2 4 2 3 3 $ 2 $ 2 4 3.4 44 0.01 2.50 glass flbor filled) r - - .,, a_ 9 . 9 _ Polyethylenes (t.DPE-HDPE low-denslty2ohlgh-demiity) 4 $ 4 5 4 5 'i 1 1 1 1-2 1.2 1-3 3-6 | 3 0.00-0.01 " ~- " ; ; : : ; " ~ ; ; i : - i L L , Polyethylenes (UHMWPE- ultra high molecular weight) 3 4 3 4 $ 4 1 1 1 [ 1 1 1 1 1 $ 4 <~0,01 .,, . ; ~ _~ , ,, ,,, ,, : : . J ; ; : _ ,_ = , ~,. Polylmides 1 1 1 1 1 1 2 3 4 '] 5 3 4 2 6 1 1 ] 0.3-0.4 [ Polyphenylerm ONdes (PPO} 4 5 2 3 4 5 1 1 1 1 1 2 1 • 2 3 0.06-0,07 (modified) i I i , ; ; ~ ._ : - : . 9 Polyphem.flene Sulfides (PPS) 1 l 1 1 1 2 i 1 I 1 1 1 1 1 2 1 1 (0.05 : - ~.__. Polyphenylsulfone= 4 4 1 [1 5 5 1 1 1 1 1 1 1 1 $ 4 0.5 L Polypropylene= (PP) 2 4 ,2 4 ~2-3 4-5 1 1 I i 1 1 2-3 2-3 4-S 2 4 0.01-0.03 Poly~r4yrene= (PS) 4 5 4 5 5 $ I S 1 5 4 5 4 tS ! 4 5 0.03 - 0.60 I _ : ,: _. . , ; ; . - : Polysultonee 4 4 t 1 5 5 1 1 1:1 1 1 1 1 3 4 0.2 - 0.3 " : 5 i ] i 3"4~ ~ : - ~ " ' -~" " Po;yurelhanes (PUR) 3 4 2 3 4:2-3,3-4 2-3 2-3 3-4 4 4 4 S 0.02 1.50 , , _ I : ! Polyvlnyt Chlorides (PVC) 4 5 1 5 5 S 1 5 1 S 1 S 2 S 4 t 5 0.04 - 1.00 ! Poiyvlnyt ChJorldu- l I i Chlorinated (CPVC) 4 ,r 1 ~ 2 S 5 1 2 1 2 1 2 2 3 4 i 5 10.04- 0.45 i . +,, L [ - " Polyvinylidene Fluorides (PVDF) 1 1 1 !1 1 1 1 1 1 2 2 3 J ,1 = I is o.o, Silicones 4 4 2 3 415 2 4 5 3 2 0.1-0.2 St-/rene Acr,/Ionitrtles (SAN) t 4 i 5 3 4 3 $ 1 3 3 :3 4 4 0.20- 0.35 ~ . U'''' (''''~) ~ 1 '1 3 1 ~ 1 i 3 2 1 ~ 4 ~ 2 ~ 1 2 O'' " O" ~ -=- , .,,: , . 2 9 Plastic property 127 Figure 2~ Guide to clear and opaque plastics Figure 2,9 Examples of the weatherability of plastics 128 Plastic Product Material and Process Selection Handbook Table 2~ 13 Examples of permeability for plastics Water Specific Gravity Vapor Resistance to Type of Polymer (ASTM D 792) Barrier Gas Barrier Grease and Oils ABS (acrylonitrile butadiene 101-1.10 Fair Good Fair to good styrene) Acetal homopolymer and 1.41 Fair Good Good copolymer Acrylic and modified acrylic 1. I-1.2 Fair Good Cellulosics acetate 1.26-1.31 Fair Fair Good Butyrate 1.15-1.22 Fair Fair Good Propionate 1.1 6- 1.23 Fair Fair Good Ethylene vinyl alcohol I. 14-1.21 Fair Very good Very good copolymer Ionomers 0.93-0.96 Good Fair Good Nitrile polymers 1.12- I. 17 Good Very good Good Nylon 1.13-1.16 Varies Varies Good Polybutylene 0.91 0.93 Good Fair Good Polycarbonate 1.2 Fair Fair Good Polyester (PET) 1.38-1.41 Good Good Good Polyethylene Low density 0.910-0.925 Good Fair Good Linear low density 0.900 0.940 Good Fair Good Medium density 0.926 0.940 Good Fair Good High density 0.94 I-0.965 Good Fair Good Polypropylene 0.9(X)-0.915 Very good Fair Good Polystyrene General purpose 1.04-1.08 Fair Fair Fair to good Impact 1.03- I. 10 Fair Fair Fair to good SAN (styrene acrylonitrile) 1.07-I.08 Fair Good Fair to good Polyvinyl chloride Plasticized I. 1 6-1.35 Varies Good Good Unplasticized 1.35-1.45 Varies Good Good Polyvinylidene chloride 1.60-1.70 Very good Very good Good 2 9 Plastic property 129 Table 2oi4 Examples of transparent plastics s,,,rk f=,,!!,,y,,, h~l,I, d.,.,c~sms Transparent ABS Good impact properties, good processibility Acrylic (PMMA) Excellent resistance to outdoor exposure, crystal clarity Allyl diglycol carbonate Good abrasion/chemical resistance, thermoset . Cellulosics Heat sensitive, limited chemical resistance, good toughness Nylon. amorphous PET, PETG Polyarylate Polycarbonate Excellent abrasion resistance, moisture sensitive Good barrier properties, not weatherable, clarity dependent on processing, orientation greatly increases physical properties Excellent UV resistance, high heat distortion Excellent toughness, good thermal/flammability characteristics Polyethefimide Polyphthalate carbonate Polyethersulfone Poly-4 methylpentene-1 Good chemical/solvent resistance, good thermal/flammability properties, inherent high color Good thermal properties, autoclavable Excellent thermal stability, resists creep UV/moisture sensitive, high crystalline melting point, lowest density o all thermoplastics Polyphenytsulfone Polystyrene Polysulfone PVC, rigid Excellent thermal stability, resists creep, inherent high color Excellent processibility, poor UV resistance, brittle Excellent thermal/hydrolytic stability, poor weatherability/impact strength Excellent chemical resistance/electrical properties, weatherable, decomposition evolves HCI gas Styrene acrylonitrile Styrene butadiene Styrene maleic anhydride Styrene methyl methacrylate Thermoplastic urethane, rigid Good stress-crack and craze resistance, brittle Good processibility, no stress whitening Higher-heat styrenic, brittle Good processibility, slightly improved weatherability Excellent chemical/solvent resistance, good toughness FAB RI s N G PRODUCT Overview The profound impact of plastic products to people worldwide and in all industries worldwide includes the intelligent application of processing these plastics. These plastics utilize the versatility and vast array of inherent plastic properties as well as the usual high-speed/relative low- energy processing techniques. The result has been the development of millions of cost-effective products used worldwide that in turn continue to have exceptional benefits for people and industries worldwide. In a market economy, which is to say the real world that is ruled by competition, processed plastics will be employed only in applications where they can be cxpcctcd to bring an overall economic advantage compared with other competing products. In this connection it is well to note that the biggest competitor to a given plastic may be another plastic with their respective processing techniques. On the basis of an overall benefit assessment taking in the full service of a processed plastic product, it has been shown in millions of cases worldwide that the use of processed plastics not only makes economic sense but also makes a contribution toward conserving resources. Thcrc arc many factors that arc important in making plastic products the success it has worldwide. One of these factors involves the use of the availability of different fabricating processes. All processes fit into an overall scheme that requires interaction and proper control of operations based on material requirements. Thus fabricating is an important part of thc ovcrall project to produce acceptable plastic products. It highlights the flow pattern for the fabricator (manufacturer) to be successful and profitable. Recognize that first to market with a new product captures 80% of market share. Factors such as good engineering, process control, etc. are very important but only represent 3 9 Fabricating product 131 pieces of the "pie." Philosophical many different ingredients blend together to produce profitable products. Fabricating is one of the important main ingredients. With continuing new developments in equipment (and plastics) their quality performance and output rate improves and overhead costs are reduced. Result has been the industry worldwide continues to be more productive even though the economy has its ups and downs. 13s, 136, 248 In order to understand potential problems and solutions of fabrication, it is helpful to consider the relationships of machine capabilities, plastics processing variables, and product performance. 1 In turn, as an example, a distinction has to be made here between machine conditions and processing variables. For example, machine conditions include the operating temperature and pressure, mold and die temperature, machine output rate, and so on. Processing variables are more specific, such as the melt condition in the mold or die, flow rate vs. temperature and so on (Chapter 1). Fabricating products involves conversion processes that may be described as an art. Like all arts they have a basis in science and one of the short routes to processing improvement is a study of the relevant sciences (as reviewed throughout this book that range from the different plastic melt behaviors to fabricating all size and shape products to meet different performance requirements). The plastic-processing target is to take the plastic in the form of pellets, powders, granules, liquids, etc. and converting them into useful products usually through a screw plasticator. Processing of plastic is an art of detail. The more you pay attention to details, the fewer problems develop in the process. If it has been running, it will continue running well unless a change occurs. Correct the problem and do not compensate. It may not be an easy task, but understanding what you have equipment-wise can help. Common features of these different processes is as follows: (a) Mixing and melting: This stage takes the plastic and in turn produces a homogeneous melt (Chapter 1). This is often carried out in a screw plasticator or compounder, where melting takes place as a result of heat conducted through the barrel wall and heat generated in the plastic by the action of shear via the screw. Homogeneity is called for at the end of this stage, not only in terms of material but also in respect to temperature. (b) Tooling: When processing plastics some type of tooling is required. These tools include molds and dies for shaping and fabricating 132 Plastic Product Material and Process Selection Handbook (c) (d) (c) products. They have some type of female and/or male cavity into or through which a molten or rigid plastic moves usually under heat and pressure. They are used in processing many different materials to form desired shapes and sizes. They can comprise of many moving parts requiting high quality metals and precision machining. Some molds and dies cost more than the primary processing machinery with the usual approaching half the cost of the primary machine (Chapter 17). Melt transport & shaping: In a screw plasticator the next step would be to build up an adequate pressure in the plasticator so that it will produce the desired shape to be fabricated. In an injection molding process pressure is applied to force the melt into a mold that defines the product shape in three dimensions (Chapter 4). In an extruder the die (that initiates the shape) can vary from a simple cylindrical shape to a complex crosshead profile shape (Chapters 5). Drawing, blowing, and forming: There are processes that use a screw plasticator melt to stretch the melt to produce orientation and desired shape, as in blow molding, thermoforming, rotational molding, and foaming (Chapters 6, 7, 8, 13). Coating and Casting: With screw plasticator or other systems the melt provides coatings and castings as reviewed in Chapters 10, 11, 16. (0 Non-screw plasticating: Reactive mixing provides the melt in reaction injection molding (Chapter 12). In compression molding the usual material is precompounded or preimpregnated prior to being placed in or around a mold (Chapters 14 and 15). (g) Finishing: The final stage after a process fabricates a product usually does not require secondary operations. However, there are materials or products that may require annealing, sintering, coating, assembly, decoration, etc. (Chapter 18). Processing techniques range from the unsophisticated (high labor costs with low capital costs) to sophisticated (zero or almost zero labor costs with very high capital costs). Production quantity, the material being processed, the available equipment, and the total cost govern decisions on the appropriate technique. Small quantities are usually produced with an unsophisticated approach. Many fabricating processes are employed. Which process to use depends upon the nature and requirements of the plastic to be processed, properties required in the finished product, cost of the process, speed, and volume to be produced. Some processes can be 3 9 Fabricating product 133 used with many kinds of plastics; others require specialized processes. Recognize that the final actual properties of a processed plastic for an application are directly related to how the plastics are processed. If process controls are not properly set up, followed, and continually rechecked to insure meeting part performance requirements, products could be improperly processed. This quality control requirement 3 on processing plastics applies to all products. With the beginning of a deeper understanding of process mechanisms and their underlying physical laws and close cooperation between theorists and practical people, has processing technology and machinery design made any real progress. This progress will always continue since new plastics and new processing techniques develop. There are the basic fabricating processes (Chapter 4-16) however many different modifications continue to be developed (Table 3.1). Table 3,t Examples of names of plastic fabricating processes adiabatic extrusion adiabatic injection molding adiabatic processing advanced composite molding air floatation airmold gas-assist injection molding autoclave adhesive bonding autoclave molding autogeneous extrusion automatic extrusion automatic molding automatic processing auxiliary equipment backmolding (Hinterspritzen) bag molding biaxially-oriented extrusion biaxially-oriented molding bladder molding blister process blow molding (different types) blown film BMC injection molding bridge reinforced plastic bulk molding compound cable extrusion calendering (different types) carded package carousel molding casting (different types) C-clamp injection molding cellular plastic molding cellular chemical blow molding centrifugal casting centrifugal molding ceramic-plastic molding chemical vapor deposition cladding closed molding coating (different types) coextruded foamed blow molding coextrusion coextrusion capping coining coinjection foam molding coinjection molding cold flow molding cold forming cold heading cold molding cold press molding cold stamping cold working, combiform comoforming cold molding compounding compound molding composite molding Compreg molding compression-injection molding compression molding (different types) computer-aided extrusion computer-aided molding computer aided processing contact molding contact pressure molding continuous coating continuous fiber spinning continuous injection molding continuous laminating continuous molding continuous strip molding controlled density molding copolymer molding corrugated pipe extrusion corrugated multilayer pipe extrusion counter pressure intrusion counter pressure molding crossflow molding cross laminating decompression molding devolatilizing extrusion devolatilizing molding die casting die-slide molding dip casting dip forming dip blow molding dip molding dip coating doctor blade coating dose molding dosing extrusion dosing molding double-daylight molding double shot molding draw working dry blend molding elastomer molding continued [...]... equipment process and program control; prevention and corrective action on primary and secondary equipment, delivery of plastic materials, material handling, storage, quality assurance; machinery and plant safety; handling tools and equipment, packaging fabricated products, and general knowledge of plastics 142 Plastic Product Material and Process Selection Handbook Important is the SPI's Plastics... fabricating plastic products in production has been and will continue to be their usual relatively low processing cost The most expensive part of practically all products is the cost of plastics Since the material value in a plastic product is roughly up to one-half (possibly up to 90%) of its overall cost, it becomes important to select a candidate material with extraordinary care particularly on long production... requirements Plastics Technology publications has set up an online website (www.plasticstcchnology.com) This action follows their annual Processing Handbook and Buyers' Guide that has been published for many decades 140 Plastic Product Material and Process Selection Handbook Even though modern fabricating machines with all its ingenious microprocessor control technology is in principle suited to perform flcxible... extrusion reaches $440 million, and thermoforming reaches $ 455 million There are now over 350 USA machinery builders with about five having over 50 % of sales 136-139 The plastics industry is comprised of mature practical and theoretical technology Improved understanding and control of materials and fabricating processes (Table 3.2) have significantly increased product performances and reduced their variability... fabrcatir,~ plastic products [courtesy o f Adaptive Instruments Corp.) I/I e-I { H~r~s E ¢ii m .-,i el "o I/i Ill f~ P) o =I -,,I el el" 0 0 ~a 3 9 Fabricating product 1 3 9 and to produce many different sizes and shapes of thermoplastic (TP) and thermoset (TS) commodities and engineering plastics, whether unreinforccd or reinforced The bases of material and process selection should be product performance... I ,3~ Cellulose Acetate - Inlectlon I I 450 FI~ 1600 1 600 N~on 6/6 450 ~ Based 1 480 1 52 5 4 25 490 PVC- ~ Profiles 420 J 470 1"~ ,,, i.,i i eio Umtw,e~=('m~) i 39o i 400 144 Plastic Product Material and Process Selection Handbook etc The melt flow is an indication of whcther its final properties will be consistent with those required by the product Subjects such as rheology, molecular... DC light source and a special video camera to measure light intensity passing through the melt flow This light intensity is affected by the efficiency of a screw to 148 Plastic Product Material and Process Selection Handbook disperse a standardized plastic/ color concentrate mix The computer software collects data during a test run and calculates a standard deviation The lower the standard deviation,... patterns resulting from the conditions of a particular fabricating process are very important in affecting product performances As the temperature increases the plastic goes through the phases of glassy, transition, rubbery, to melt flow The melting of plastics follows different phases that effect performances 487 1 50 Plastic Product Material and Process Selection Handbook Reinforcing fibers, specifically... Nomenclature of an injection barrel (top) and extrusion barrel (courtesy of Spirex Corp.) 1 58 Plastic Product Material and Process Selection Handbook Figure 3.7 Assembled screw-barrel plasticator for injection molding {top) and extruding {courtesy of Plastics FALLO) Transition Zone: It is the section, also called the compression zone, of a screw between the feed zone and metering zone in which the flight... toughness, as well as craze and microcrack resistance in the direction of the plane or the plane of orientation By far the main source of 154 Plastic Product Material and Process Selection Handbook orientation is with fibers that cause positive and significant increased performance Such effects are obvious in continuous filament winding (Chapter 15) Not so obvious are the anisotropic materials properties . 2 9 Plastic property 127 Figure 2~ Guide to clear and opaque plastics Figure 2,9 Examples of the weatherability of plastics 128 Plastic Product Material and Process Selection Handbook. Tooling: When processing plastics some type of tooling is required. These tools include molds and dies for shaping and fabricating 132 Plastic Product Material and Process Selection Handbook (c). -5 I-S S 1 S $ IS 1 i-~ 1 0.22-0.2S L : : - : ' " - i Acrytics 5 5 2 3 5 5 1 3 2 S 4 4-S 5 6 5 $ 02-0.4 _. [ .: _ . J + ' 1 i 2 3 -5 + Acry~nltdk)-lutadtlne- 4 5 3 -5 5