Group No 07HISTORY World War IIDevelopment of Thermoplastics, windshields 1950’sHigh volume production and products ofthermoplastics.Development of blister packagingFood packaging divisions 1980’sFlexibility in size of containers use by the machine TodayIn addition to packaging, used for refrigerator liners,shower stalls, bath tubs, automotive trunk liners andmore
What is Thermoforming?Thermoforming is the processinvolving heating a plastic sheet andforming it into a cavity or over a toolusing vacuum, air pressure, andmechanical means.
The MoldO Two major types: Maleand FemaleO Male molds have theconvex (inner) side againstthe mold; the concaveside is against the moldface in female molds.O Mold type should bechosen so that theimportant sidecontacts the mold.O Off side is harderto control shape.
TYPES OF THERMOFORMINGO Vacuum ThermoformingO Pressure ThermoformingO Mechanical Thermoforming
Vacuum ThermoformingO The process involves shaping a preheatedthermoplastic sheet by means of vacuumproduced in the mold cavity space.O The atmospheric pressure forces the softsheet to deform in conformity with thecavity shape.O When the plastic comes into the contactwith the mold surface it cools down andhardens.
Pressure Thermoforming:-O The process involves shaping a preheatedthermoplastic sheet by means of airpressure.O The air pressure forces the soft sheet todeform in conformity with the cavityshape.O When the plastic comes into the contactwith the mold surface it cools down andhardens.
Mechanical Thermoforming:-O The process involves shaping a preheatedthermoplastic sheet by means of a directmechanical force.O A core plug (positive mold) forces the softsheet to fill the space between the plugand the negative mold.O The process provides precise dimensionaltolerance and surface detailing.
Thermoplastics which may beprocessed by the thermoformingmethod are:O Polypropylene (PP)O Polystyrene (PS)O Polyvinyl Chloride (PVC)O Low Density Polyethylene (LDPE)O High Density Polyethylene (HDPE)O Cellulose AcetateO Polymethylmethacrylate (PMMA)O Acrylonitrile-Butadiene-Styrene (ABS)
Advantages They are light in weight and durable. They reduce per unit packaging cost of the product. Thermoforming can be recycled thus technology isenvironment friendly The plastic used for packaging is stiffer than the averageplastic. This gives the products a high quality packaging. The transportation costs are reduced as the packagingdoes not add to the total weight of the product. Low Temperature required Low pressure required Fast mold cycle
Disadvantages Limited shape complexity. Trimming is required . Parts with sharp bends and corners are difficultto be produced. Generates greater amount of scrap. Internal stresses are produced.
COMPARISIONPRESSURE FORMING VACUUM FORMINGO Mold cycle is fast.O Sheet can be formed atlower temperaturebecause the forcingpressure is high.O Greater dimensionalcontrol.O Mold cycle is slow.O Sheet can beformed atcomparatively hightemperature.O Dimensionalcontrol is less.
WHAT IS EXTRUSION…???Extrusion is a process used to createobjects of a fixed cross-sectional profile.A material is pushed or drawn through adie of the desired cross-section.
HISTORYO In 1797, Joseph Bramah introduce the firstextrusion process for making lead pipe. Itinvolved preheating the metal and thenforcing it through a die via a hand drivenplunger. The process wasnt developeduntil 1820 when Thomas Burr constructedthe first hydraulic powered press. At thistime the process was called squirting. In1894, Alexander Dick expanded theextrusion process to copper and brassalloys.
PROCESS:The process begins by heating the stockmaterial. It is then loaded into thecontainer in the press. A dummy block isplaced behind it where the ram thenpresses on the material to push it out ofthe die. If better properties are requiredthen it may be heat treated or coldworked.
HOT EXTRUSION:Hot extrusion is a hot working process, whichmeans it is done above recrystallizationtemperature to keep the material from workhardening and to make it easier to push thematerial through the die. Most hot extrusionsare done on horizontal hydraulic presses.
COLD EXTRUSION:Cold extrusion is done at room temperature ornear room temperature. The advantages of thisover hot extrusion are the lack of oxidation,higher strength due to cold working, closertolerances, good surface finish.
WARM EXTRUSION:Warm extrusion is done above roomtemperature, but below therecrystallization temperature of thematerial. It is usually used to achieve theproper balance of required forces,ductility and final extrusion properties.
DIRECT & INDIRECT EXTRUSION:O DIRECT EXTRUSION:Direct extrusion also termed asforward extrusion. If the die is held stationary andthe ram moves towards it then its called “directextrusion”.O INDIRECT EXTRUSION:Indirect Extrusion is alsotermed as backward extrusion. Here the die is notstationary and moves with respect to the ram.
HYDROSTATIC EXTRUSION:In the hydrostatic extrusion process thebillet is completely surrounded by apressurized liquid, except where thebillet contacts the die. This process canbe done hot, warm, or cold, however thetemperature is limited by the stability ofthe fluid used. The process must becarried out in a sealed cylinder to containthe hydrostatic medium.
EXTRUSION ADVANTAGES ANDDISADVANTAGES:ADVANTAGES: DISADVANTA-GES:O Continuous.O High productionvolumes.O Low cost.O Many types of rawmaterial.O Surface cracking.O Internal cracking.O Uniform cross-sectional shapeonly.
PREFERENCES:O Low labour cost.O High production rates.O Cost efficient.O No need of surface finish afterextrusion process.O Minimum scrap losses.
HISTORYO The first man-made plastic was invented in Britain in 1851by Alexander Parkes. He publicly demonstrated it at the 1862International Exhibition in London, calling the material he produced“Parkesine”.O In 1868, American inventor John Wesley Hyatt developed a plasticmaterial he named Celluloid, improving on Parkes invention so thatit could be processed into finished form. Together with his brotherIsaiah, Hyatt patented the first injection molding machine in 1872.O The industry expanded rapidly in the 1940s because World WarII created a huge demand for inexpensive, mass-produced products.In 1946, American inventor James Watson Hendry built the firstscrew injection machine, which allowed much more precise controlover the speed of injection and the quality of articles produced.O The plastic injection molding industry has evolved over the yearsfrom producing combs and buttons to producing a vast array ofproducts for many industriesincluding automotive, medical, aerospace, consumer products,toys, plumbing, packaging, and construction.
INJECTION MOLDINGInjection molding isa manufacturing process for producingparts fromboth thermoplastic and thermosetting plastic materials. In injection molding material isfed into a heated barrel, mixed, and forcedinto a mold cavity where it cools andhardens to the configuration of the moldcavity.
THERMO PLASTIC:O A thermoplastic, also known as athermo softening plastic, is apolymer that turns to a liquidwhen heated and freezes to a veryglassy state when cooledsufficiently. Nylon, polyethylene,and polystyrene are examplesof thermoplastic.
THERMOSETTING PLASTIC:A thermosetting plastic, also known as athermoset, is polymer material thatirreversibly cures. The cure may be donethrough heat (generally above 200 C(392 F)), through a chemical reaction(two-part epoxy, for example), orirradiation such as electron beamprocessing. epoxy and phenolic areexamples of thermosetting plastics
APPLICATIONS:Injection molding is used to create manythings such as wire spools, packaging,bottle caps, automotive dashboards,pocket combs, and most other plasticproducts available today. Injectionmolding is the most common method ofpart manufacturing. It is ideal forproducing high volumes of the sameobject.
COMPARISON B/W INJECTONMOLDING AND OTHER PROCESSINJECTION: BLOW:O Mold remain sealed throughout the processO In injection molding we keepair pressure very low becausemore air pressure candiminish the product.O The injection moldingprocess ends inside the moldmeans the process ends afterthe ejection of the mold.O it employs a narrow nozzleto coupled with the mold.O In this process mold remainsplit a part.O In blow molding we forcemore and more air into themold to expand the plastic tothe limits of the mold cavity.In this process mold remainspilt apartO In blow molding process doesnot end inside after theejection of the product somemore processes like airblowing and trimming areperformed.O It employs die head extrudesa tube of molten plastic.
APPLICATION IN PAKISTANINDUSTRIESO Siddiqi sons industries.(Fan parts, Citrus press juicers,Television parts)O Arfeen international (pvt) ltd.O Qismat plastic industry(spare parts ofwashing machine, spare pats of fans).O Universal Engg works(specialize inplastic and metal products).
BLOW MOLDINGO It is amanufacturingprocess to madehollow partssuch as plasticbottles withuniform wallthicknesses.
HISTORYO Enoch Ferngren and William Kopitkewere the first verified people who usedthe Blow Molding Process. The processprinciple comes from the idea ofblowing glass. Ferngren and Kopitkeproduced a blow molding machine andsold it to Hartford Empire Company in1937. This was the beginning of thecommercial blow molding process.
PROCESS:The blow molding process begins withmelting down the plastic and forming itinto a parison or preform. The parison isa tube-like piece of plastic with a hole inone end in which compressed air canpass through. The parison is thenclamped into a mold and air is pumpedinto it. The air pressure then pushes theplastic out to match the mold. Once theplastic has cooled and hardened themold opens up and the part is ejected.
EXTRUSION BLOW MOLDING:O Extrusion Blow Molding is thesimplest type of blow molding. Ahot tube of plastic material isdropped from an extruder andcaptured in a water cooled mold.Once the molds are closed, air isinjected through the top or theneck of the container; just as ifone were blowing up a balloon.When the hot plastic material isblown up and touches the wallsof the mold the material"freezes" and the container nowmaintains its rigid shape.
INJECTION BLOW MOLDING:O Injection blow molding is aprocess used to make hollowproducts, such as drinks bottles, inlarge quantities.O The process is divided in to threestages,O injection, blowing and ejection.
STRETCH BLOW MOLDINGO Stretch blow molding is best knownfor producing PET bottlescommonly used for water, juice anda variety of other products. theplastic is first molded into a"preform" . These preforms areproduced with the necks of thebottles, including threads on oneend. Then these pre-forms are sendto molds . And there these pre-forms are blown in the shape offinal product.
APPLICATION IN PAKISTANINDUSTRIESO Tabraiz mold engineering LahorePakistan. ( products: pet blow mold,machine parts, labeling parts)O Thermosole industries (pvt) ltd.Kotlakhpat. (covering 90% of blowmolding automotive market inPakistan)O Kalson engineering in Lahore.(services in mold making)