Plastic and Polymer Composite Fabrication Processes

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

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

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 6

Injection Molding Equipment Clamping Unit (Ejection System) Injection (Plasticating) Unit Frame 7

Injection Molding Main functions of Plasticating unit Convey solid material/melt Mix to produce homogeneous melt Melt material Range of 300º F (PVC) to 740º F (Polysulphone) Develop pressure for injection 8

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 9

Injection Molding Parts Three dimensional Can be very complex Multiple cavitation is common (128 cavities) 10

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 11

Extrusion Process Plastic pellets or powders are heated in a plasticating unit and the melt is forced through a forming die. Continuous Process 12

Extrusion Equipment Injection (Plasticating) Unit Frame 13

Extrusion Materials Both amorphous and semi-crystalline are done easily Wide molecular weight distribution 14

Extrusion Parts Two dimensional Sheet Hoses Line Rod Vinyl siding Pipes 15

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

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. 17

Thermoforming Process 18

Thermoforming Process 19

Thermoforming Process 20

Thermoforming Equipment Heating unit Vacuum unit Tool or die 21

Thermoforming Materials Both amorphous and semi-crystalline are done Semi-crystalline are more difficult Wide molecular weight distribution 22

Thermoforming Parts Three dimensional Generally simple shapes 23

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 24

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. 25

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 26

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 27

Blowmolding Parts Three dimensional Generally simple shapes Hollow May need trimmed 28

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 29