Ch 6 METBD 470 Chapter 9 – Plastic and Polymer Composite Fabrication Processes 1.Injection Molding (or compression or transfer) 2.Extrusion 3.Thermo-Forming.

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1 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)

2 Ch 6 METBD 470

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

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5 Ch 6 METBD 470 You Tube Videos: Blow Molding: http://www.youtube.com/watch?v=vSabFFQUr9E&feature=related http://www.youtube.com/watch?v=vSabFFQUr9E&feature=related Extrusion: http://www.youtube.com/watch?v=kpPS6S_EB4Qhttp://www.youtube.com/watch?v=kpPS6S_EB4Q Injection: http://www.youtube.com/watch?v=bit- D1NnfjI&videos=BeAyHeQIsiY&playnext_from=TL&playnext=1http://www.youtube.com/watch?v=bit- D1NnfjI&videos=BeAyHeQIsiY&playnext_from=TL&playnext=1 Thermoforming: http://www.youtube.com/watch?v=NPLWxxyIJcE

6 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

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

8 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

9 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

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

11 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

12 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

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

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

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

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

17 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.

18 Ch 6 METBD 470 Thermoforming –Process

19 Ch 6 METBD 470 Thermoforming –Process

20 Ch 6 METBD 470 Thermoforming –Process

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

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

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

24 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

25 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 http://www.youtube.com/watch?v=RcXB0NbbQzg&feature=related Injection Blow Molding (large volumes) –Uses preforms - The preform is transferred on a metal shank, called the core rod and into a blow mold.

26 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

27 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

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

29 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