INTRO MANUFACT PROC
INTRO MANUFACT PROC TSM 240
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This 45 page Class Notes was uploaded by Nestor Hamill on Saturday September 26, 2015. The Class Notes belongs to TSM 240 at Iowa State University taught by Staff in Fall. Since its upload, it has received 42 views. For similar materials see /class/214419/tsm-240-iowa-state-university in Business, management at Iowa State University.
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Date Created: 09/26/15
5 Polymers 1 Polymers 7 PolyMers Back bones CC hydrocarbon 105 113 rotation SiSi Silicone 104180o rotation Chemical structure Mostly plastic are made from CCarbon 4 active sites 12 gmole HHydrogen 1 1 gmole OOxygen 2 16 gmole CIChlorine 1 35 gmole F Fluorine 1 19 gmole nalogy Plastic and Spaghetti Hard to pull out individual Noodle molecule from System 1 Chemical structure Monomer Polyethylene HDPE later we will add a CHHZWJ side group to make LDPE Rammm H H H H H H H H H H H H H I I I I I I I I I I I I I oc a c c c c c c c c c c I l I I I I I I l l l H H H H H H H H H H H H H Elhene Poin g Chemical structure Polypropylene H CH3 H CH3 H H H WW I I I I I I I I Saddam39s C39C39C39C3939C39C39 HHHH HCH3HH a Chemical structure Polyvinyl Chloride venuequ CCCCCCCC I I I I I I I I HHHH HHHH 1 Mechanical properties We will return to more chemical structures Thermnr SEWlV Wmum Thermoplastics For thermoplastics the chains are similar to spaghetti c Nslalline cmsslinks egmn lhemi asel a Thermoplastics Amorphous materials The chains can slide past each other Widow glass is amorphous Over time even with a small load they will move Strength is very temperature and rate dependent silly putty 1 The backbone CC Stiff Most plastics SiSi Silicones Flexible High temperature Chemical bonds Backbone and side groups Colvalent bondsvery strong Chain to chain Hydrogen bonding weak van der Waals weak Ionic strong Other etallic strong SI Side groups They define the plastics and its properties Mechanical Thermal Solvent resistance Morphology The big 6 Noted on most products as numbers 1 PEI39 polyethtlene terephthalate m 2 Highdensity polyethylene h WW 3 PVC I Big6 4 Lowdensity polyethylene Branched HDPE H is replaced with QHZWI w v i I t t 4flililililililililililililili gig r tf am n m u m N mi N m M m n w i an H un Syndiotatctic Random atatic lBigS 6 Fblystyrene g Other important polymers Teflon no stick Nylon under the hood applications ABS electronic housing PC High impacthead lights Kevlar Toughbullet proof El CoPolymers By polymerizing to polymers together we can get superior properties ABS Wide range of propertis Many application Hard snong 5 Co Polymers Block ABABABAB B ra n ch ed AAAAAAAA B B 1 Polymerization Addition Opening ofdouble bond CH2CH2 CH2CH2 CH2CH2 Condensation Step PU HOCHZCHzWCHZCmNCO HOCHZCH2OCONHCH2CH2NCO Polymerization Condensation PET HOCHZCH2WCOCH2CH2COOH HOCHZCH2OCOCH2CH2COOH H20 a Polymerization Addition Long molecules quickly Monomers decrease steadily Condensation Molecules grow steadily Monomers quickly disappear 1 Polymer blends By migtlting polymers we can also get superior properties A er polymerization Easily to control mixing ratio No chemical bonds Often need to add coupling agent ABSPC blends Similar to alloys Usually there is a continuous phase Thermosets Cross linked No massive molecular motion with heating Increased free volume with heat which decrease stiffness Once formed can not be reshaped with heat High temperature applications Bowling ball a Morphology ovyslaiime Cmss links vegiun Amuvphuus Semircvy allme Thevmusel lhevmuplashc lhevmuplashc 1 Crystalline structure Even crystalline polymers are only partially crystalline Semicrystalline HDPE 7090 0965 gcc LDPE 4555 09160930 gcc Crystalline is defined by Chemical structure Thermal history Crystalline structure PE has no side group This allows the chains to fold on each other PS has large benzene side group which prevent the chains from folding one each other in an orderly fashion g Crystalline structure Spherulite hiya Ilulb winquot uu u wlimllle all Crystalline structure Lemella Iu nh unbhmnd nfkthw HQHI chm anaemi W quotin l I Crystallinitystop Degree of crystallinity Q QQ5 V5 39 Q5Volume fracuon ofcrvstalllnlty in Spherulite 39 V5Volurnefracl10n of Spherulite 39 Avrami Equation r V 1 e S 39 KRate parameter 39 NMatenal parameter geomath factor 39 Tlrne s Crystallinity n 35 e 35n kle nmenm395e 725 w a l wens l 2 0 5 E El 1 Crystalline materials Higher temperature More solvent resistance Why Fuel tanks liquid contact Tail lights Model airplanes More dense Add39 39ves me rmson in add additives reinforcements and ers To improve processability To reduce cos To reduce shrinkage To improve surface nish co 0 mechanical properties To lower the coef cient of friction IIIu mmummAwNH l l o o 3 13 ltg o 39 u lt 3m m nquot 3 n 5 l m n q a n E o 1 m a m m I Additives Increase properties of plastics Strength Glass bers Graphite bers Kevlar bers Wood bers Impact strength Particles Talc 1 Plastisizers Increase flexibility Reduce melt temperature Lower viscosity Water Mild solvents Commercial Dioctyl phthalate UV stabalizers Carbon black UV can CC backbone and many side groups Brittle Weaken Other additives 2hydrocybenzophenone p 1 Hard To Separate NoodlesMolecules Easily to Separate wwwmadisongroupcom Cup NoodlesMles Water Heater Drain Valve Chemical Attack Example ttcko quot Plastic Discoloration of Plastic quot wwwmadisongroupcom Analogy En ironme ntal Stress Cracking NoodlesMolecules are Lubricated Easy to Separate wwwmadisongroupcom 13 Francis bee Commander r w u 39 9 H ey wwwmadisongroup com gs this a Plastic Failure www madisongroupcom 5 Flame retardant Ammonium phosphate Chlorinated hydrocarbons Chemicals of bromine chlorine antimony Effects Emit fireextinguishing gas C02 N2 Form an insulation barrier against heat and ame 1 Foaming agents Physical decompose at specific temperatures releasing gases Chemical reease gases due to a chemical reaction Uses Polyurethane pads seats for ca rs trucks sofas Internal lubricants Lubricants 3 reasons 1 Lower external and internal friction 2 Nosticking to the mold 3 Prevent products from adhering to each other Examples Waxes montan carnuaba paraf n Metallic soaps g Thermal properties mm 4an vw mu m 1mmle r m a Molecular weight A meaaue of the balm length MW 2W 322313 M ZMWNW We me wzpm w l Hummus WWW um ms a Molecular weight W50000000038000000000 13 1 Average Welght WMwo 13110000013158 TV VlVlWNl TW yaw Averagewelghl w Averagenumbev 5mm annuuuuuu mama 13158 DZE lSE 25315 zuuunu anun launuununu 14735 94737 umem 94737 annuuu 5mm lsunuununu U394737 1 DZE lSE 47 19nnn a nnnnnnnn 1 1 mm lVln MW N5000190000 263 Average number DDNWW 0 26310000026316 1 Molecular number If all the chains are the same the polymer is monodispersive No polymer is monodispersive Degree of polymerization Is the number of monomers added together SI Molecular weight and strength imam Wmm I Viscosity Measure ofliquid ow Resistance of ow Higw viscosity has high resistance oney Q Low viscosity has low resistance l Alcoho Melt indexer ASTM D1238 SI Viscosity Newtonian Rate independent Water NonNewmnian Rate de endent CaBup Decreases Wm ow oney increases wmw ow Lower Newtonian Platform e Newtonian quotf u H Plastics Typically decrease Wm ow a Shear thinning Molecules line up during flow This decreases drag Decreases viscosity Shear thinning Poor molecular alignment if frozen 1 Viscoelastic models As we reviewed plastics move Creep Movement with constant applied stress Stress relaxation Reduction of stress with constant applied displacement Viscoelastic molds In order to help understand material behavior as technical people we use models Two main modeling elements Spring Dampener Viscoelastic molds Spring Hook solid Equilibrium ZF0 Compatibility 22 Constitutive oEe Fkx F F Fk XAL Viscoelastic molds Dampener Newtonian liquid FB xv F E F Fn X dedt Viscoelastic molds Maxwell model Maxwell fluid g constant EF1Eg ampener coeff 2O Viscoelastic molds Maxwell model Wm mdi liw dt dt 5 k y xl d k a ma 5 c j m A57 Viscoelastic molds Maxwell model Relaxation 61 1 Viscoelastic molds Kelvin or Voigt model Voigt solid 2 mm a Homos mn 1 I in a quotTu 5amp7de my CztA27 magma a z I Stress Strain 21 a Mechanical properties Tensile strength has been defined FatigueWhile plastics most plastic do not follow convention models a good start is SN curve stresscycle 1 Fatigue 7 Stress gtlt ampllmde X Endurance Stresslimit nin nity Loom m 0a n C rnrnatenal constant constant nnumber of cycles to failure Fatigue k51 100P51 cycle Hzsec m 10 ca 2ksi C 221ksi1 0 cycle C N N 2048 m Ua The Basics of FEA A Dr Grewell Basic Equation Total potential energyTr Kinetic Energy strain energyU Potentia Energy of the loads W HU W Basic Equation The total change in potential energy of a system is zero about the minimum energy state thus 5H 0 or 0fori012 611 z Example I Simple spring 1 SU 5W 7 k WFu u Hku27Fu 6Hi1 ku2iiFu Bu Bu 6112 Example I Simple spring 6H 6 1 6 ku 7 Fu 0 W au 5J2 6u 6H 2 ku 7 F 0 ii 6 lt2 gt lt gt kuiF0 kuF CSpring equation ExampleMore realistic I Simple rod EM udulus AArea Ax du 3917 F 2 du u LLength ExampleMore realistic I Simple rod EZMudulus ZArea 1 du 2 H 34 dx Fu 7 u 7 0 2 dx x71 LLength ExampleMore realistic l 2 I Simple rod H dxiF 0 2 dx 39 u EMudulus AArea Fl This is a simple case where an exact solution cab be found However n general a displacement field is assumed resulting in a system ofequations in the rm LLength K F 3 And these are solved for u displacement ExampleMore realistic I 2 element Simple rod Area A Modulus E For elem ent 1 From a straight line approximation u u ux But we need dx ExampleMore realistic I 2 element Simple rod For element From a straightline approximation u ux 7 2cu2 But we need dx ExampleMore realistic I 2eementSimple rod 1 uiuJZ 1 uiuJZ H EA 2 dz EA 3 2 deruz l2 22 52 4 l E 2 7 21 I 2 7 21 HEA quot1 21 quot x EA 3 2 25 3 x 4n A n A 54 2 7 2 2 7 2 HEA 7 H 21 quot 0EA quot3 2 35 LrFu3 2 2 V 5 2 2 2n u 7 2M 25 Fug ExampleMore realistic I ow find minimum for each displacement an E aim L 2 41 211 Inmam39xform ul 2 3 EA 2 72 0 u 0 72 4 72 142 0 L 0 72 2 143 F ExampleMore realistic l ow find minimum for each displacement W1Lhu10 ul uz u3 E72 4 72 200 L 72 u F EA4 72 270 L72 2 ujiF In linear algebra you can not divide so we take the invase l2 Zldlill2l ExampleMore realistic 4 72 quot 0 142 liz zl lFHul Gaussian elimination 4142 72143 0gt4u2 2143 32142 143 then With the other equation r 2142 2143 E EA Sub in Zu2 u3 FL FL ru32u3au3 ExampleMore realistic FL 3 EA 050E5 A 531 L l InMatrixfmm 2 HS 2 e2 0 u 0 e2 4 e2 22 0 L 72 2 113 F x T v if F Force matrix is known we can solve roru1u2 etc displacement matrix in general for exact solution or any elastic problem one must Equilibrium ionstitutive relationship iompatibility K stiffness matrix FEA Basics In FE we pick a specific displacement pattern and satisfy the principle of virtual workthese patterns Therefore equilibrium is satisfied integrally for an element but not at every point with the element Compatibility is satisfied because the total strains are calculated once the arbitrary displacements are found A VT mw L 39 rum 3 Mo d ow mm mm 3 1 Mama 2 use Mnlgmlg Du r mum Mold Shrinkage o Shrwnkage m the mrecuun uf uvws usuaHy much greaterthan arms the uwmr unr HEd matema s Deslgn Prlnciples H yuu dun t have In get tnts Moldflow Design Philosophy o Nurnperettgates a The nurnperet gates useg ts paseg an the pressure tet rttt tne avtty tn generat etne seteets tne rntntrnurn nurnper pr gates tet rttt tne eavtty o F39Elsmun utgates a The pustttetn urtne gate ts geterrntneg by the new patanetng prtnetpte o Ftpw pattern a The rnettg snuutgrttt wttn a stratgntrttt pattern wtm nu t nanges tn gtreettetn gurtng rttttng Moldflow Design Philosophy o Runner Destgn a The runnersystem ts gestgnegtp acmeve tne regutreg ern tn tne eavtty o Seguenee ptAnatysts u The preteegure prtne rnettg gestgn atways starts wttn tne avtty Project Design Procedure Using Mold ow 0 Determine the design criteria for the project Use previous experience ofana s Discuss the project with all disciplines involved in the ro39ect Use Mold ow Design Principles Use Mold ow Design Rules with the soitware Interpret results and make chan es where necessary Discuss changes with all disciplines involved in the on 13 00 1 e eat Mold ow analysis to ensure acceptable UniDirections and Controlled Flow Pattern The unidirectional flow principle says that the plastic should flow in one direction with a straight ow front throughout filling This gives a unidirectional o 39 39 atte e 7 i or m di erenl Dirsminnsmnwmm highsirsssss ampwzrping inn leniln v551 n2 rm rvssvs shrinkage Flow Balancing o The ow balancing principle says all ow paths within a mold should be balanced ie ll in equal time with equal pressure 0 Naturally balanced runner system 0 Same distance and conditions between the nozzle and all cavities o All cavities filling at the same time pressure and perature 9 Flow Balancing o Arti cially balanced runner system 0 Sizes ofthe runners are different in order to deliver plastic melt to all cavities at the same pressure so that all the cavities ll at the same time Flow Balancing o Arti cially balanced runners Limitations Verysmall part5 Part5 which contain verythm sections I iii TE Constant Pressure Gradient o The constant pressure gradient principle says that the most ef cient lling pattern is when the pressure gradient ie pressure per unit length is constant along the ow path m u l re s pikin ms 9 at end nHill helan switcther lowers miss ure Maximum Shear Stress HUEa eve The vame ufthws EHUEa eve depends mh e an the mate a and apphcat Magma AES Wesshm DJMDa shess v a eds nqu maleua hmn Unlform Coollng When wash 5 h cuntamthh the mu d and ehe swde en a and the ethens hep uherehuax EDD hg takes mace Tm causes uvvmgtuthe hutswde asthe hut swde takes Dngertu cum and shth U orm Coolan o Part Erussrsectmn shumd eem Even y cavmtu cure W WWW than an degrees pruducmg the ypma buvved bux Warpage Bore m e cancemvakd m cav y Hm he mm Mme cave cum o Pusmun We d and we d hnes m the 2351 sensmve areas w they can t be Ehmmated u We d Lmes arefurmed when We ew francs meet an head a MEM Lmes are farmed Whentwu uw rmnts meetand ew m the same mrectmn Posltloning Well and Muld Lines Avoid Hesitation Effects o Pusmun gates asfaravvay as pussmxe frum Where the aw ewes mm thmk and mm uvv paths m avmd heswtatmn Effects B Avoid Hesltation Effects GATES make war aw enmml d 39 as stmm E Law vvessuve amp m Mmmecww mum mm hanuvM cw N aw um mm mm m vasm mm mm cavmes Avold Under ow o A change m uvv dwrectmn between the me an area MS and the nu umu The blue ve umty ang e arruvvs mum be perpendmu artu me mumcolomu untuur hnes Good Balancing with Flow Leaders and Flow Deflectors Sub y mcrease themhng pattern m wnmn the pan Acceptable Runnerlsavily Ratio 0 Design runner systems for high pressure drops give a low ratio of runner to cavity volume Vuiume uf parts 192 D E em 13 4 cc Feed system 7 D uf part vuiume Moldflow Models 0 Midplane o FusionTM 0 3D Dual Dmnzinmmesh 3 5mm mesh Midplane o Mesh is 3 noded triangles o Represents center line or midplane ofthe plastic cross sect39on 0 Thickness assigned as a property for each element 0 Used on thin walledquot parts Fusion Mesh ts 3 HDdEd thahgtes o The thahgtes are eh the surface uf the ptastte part o Trtang es matched ehe stue tn the ether o Tmckness de ned by the mstahee between matched etem t ehts o Used uh thm WaHEd parts o Eastertu mudetsume geumetry transmuns such 3 HbStEI humthat WaH 3D o Mesh ts 4 nDdEd tetrahedrat etemehts o Best used eh thtck chunky parts Where mtuptahe and Fusmnm Wm nutvvurk o shhutates actuaMquruntadvancement Us M 11min iwwmmmmmWMMc dWMmmmmm WWWWMMan MMMmem 39WMWWWWMWMM mmmmmmmmmma mmmwmwmmmw
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