Ch 6 METBD 470 Chapter 9 – Plastic and Polymer Composite Fabrication Processes 1.Injection Molding (or compression or transfer) 2.Extrusion 3.Thermo-Forming 4.Blow Molding (injection blow molding with preforms or extrusion blow molding with parison) 5.Rotational Molding (combination of 3 and 4)

Ch 6 METBD 470

Molding Processes for PE: Molding Processes for Nylon (30% GF):

Ch 6 METBD 470 You Tube Videos: Blow Molding: Extrusion: Injection: D1NnfjI&videos=BeAyHeQIsiY&playnext_from=TL&playnext=1http:// D1NnfjI&videos=BeAyHeQIsiY&playnext_from=TL&playnext=1 Thermoforming:

Ch 6 METBD 470 Injection Molding – most common (60-70%) –Process Plastic pellets are heated in the injection unit and forced through a runner system/gate(s) into a cavity in a mold. Batch Process

Ch 6 METBD 470 Injection Molding –Equipment Clamping Unit (Ejection System) Injection (Plasticating) Unit Frame

Ch 6 METBD 470 Injection Molding –Main functions of Plasticating unit 1.Convey solid material/melt 1.Mix to produce homogeneous melt 1.Melt material –Range of 300 º F (PVC) to 740 º F (Polysulphone) 1.Develop pressure for injection

Ch 6 METBD 470 Injection Molding –Materials Both amorphous and semi-crystalline are done easily Narrow molecular weight distribution With modifications to the equipment – thermoset materials and liquid Silicone can be used

Ch 6 METBD 470 Injection Molding –Parts Three dimensional Can be very complex Multiple cavitation is common (128 cavities)

Ch 6 METBD 470 Injection Molding –Tooling - Molds Generally steel, but some Aluminum tooling is used High pressure process – molds are ‘beefy’ –Plastic pressures around 30,000 psi –Weight – LXWXH/4 (in inches) Tooling is expensive and can take a long time to create

Ch 6 METBD 470 Extrusion –Process Plastic pellets or powders are heated in a plasticating unit and the melt is forced through a forming die. Continuous Process

Ch 6 METBD 470 Extrusion –Equipment Injection (Plasticating) Unit Frame

Ch 6 METBD 470 Extrusion –Materials Both amorphous and semi-crystalline are done easily Wide molecular weight distribution

Ch 6 METBD 470 Extrusion –Parts Two dimensional –Sheet –Hoses –Line –Rod –Vinyl siding –Pipes

Ch 6 METBD 470 Extrusion –Tooling - Dies Generally steel – Aluminum is common though Low pressure process –Tooling can be expensive –Shorter lead times

Ch 6 METBD 470 Thermoforming –Process Sheet is heated and formed to the desired shape Can be a batch or continuous process Some consider Thermoforming to be a secondary process because the material needs to be formed into sheet prior to being thermoformed.

Ch 6 METBD 470 Thermoforming –Process

Ch 6 METBD 470 Thermoforming –Process

Ch 6 METBD 470 Thermoforming –Process

Ch 6 METBD 470 Thermoforming –Equipment Heating unit Vacuum unit Tool or die

Ch 6 METBD 470 Thermoforming –Materials Both amorphous and semi-crystalline are done –Semi-crystalline are more difficult Wide molecular weight distribution

Ch 6 METBD 470 Thermoforming –Parts Three dimensional Generally simple shapes

Ch 6 METBD 470 Thermoforming –Tooling – Dies or molds Generally Aluminum, but prototypes are commonly made epoxy, wood, plaster, and composite materials Low pressure process –Tooling is relatively inexpensive –Shorter lead times

Ch 6 METBD 470 Blowmolding –Process –2 basic types Extrusion Blow Molding –consists of an extruder that melts the plastic and forms it into a molten tube called a parison. Die closes around parison which seals both ends. Blow pin is insereted and inflates the parison to assume the contoru of the die. See Injection Blow Molding (large volumes) –Uses preforms - The preform is transferred on a metal shank, called the core rod and into a blow mold.

Ch 6 METBD 470 Blowmolding Equipment Depends on type of blowmolding you are doing –Extrusion »Extruder »Dies and Blowpins »Clamping system –Injection »Preforms (Injection molding machine) »Heating unit »Blowing machine

Ch 6 METBD 470 Blowmolding –Materials Both amorphous and semi-crystalline are done –Semi-crystalline are more difficult –Highly Crystalline materials (Nylon) are very difficult Wide molecular weight distribution

Ch 6 METBD 470 Blowmolding –Parts Three dimensional Generally simple shapes Hollow May need trimmed

Ch 6 METBD 470 Blowmolding –Tooling – Dies or tools Generally Aluminum (some may have brass inserts) –Steel Pinchoff areas Low pressure process –Tooling is relatively inexpensive –Shorter lead times