Chapter 9 – Plastic and Polymer Composite Fabrication Processes

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Chapter 9 Plastic and Polymer Composite
Fabrication Processes
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Molding Processes for PE
Molding Processes for Nylon (30 GF)
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You Tube Videos Blow Molding
http//www.youtube.com/watch?vvSabFFQUr9Efeature
related Extrusion http//www.youtube.com/watch?
vkpPS6S_EB4Q Injection http//www.youtube.com/w
atch?vbit-D1NnfjIvideosBeAyHeQIsiYplaynext_fro
mTLplaynext1 Thermoforming
http//www.youtube.com/watch?vNPLWxxyIJcE
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• 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

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

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• 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

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• 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

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

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• 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

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

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• Extrusion
• Equipment
• Injection (Plasticating) Unit
• Frame

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

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

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

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• 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.

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• Thermoforming
• Process

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• Thermoforming
• Process

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• Thermoforming
• Process

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• Thermoforming
• Equipment
• Heating unit
• Vacuum unit
• Tool or die

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

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• Thermoforming
• Parts
• Three dimensional
• Generally simple shapes

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• 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

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• 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?vRcXB0NbbQzgfeature
  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.

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• 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

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• 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

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

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• 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