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Plastics
are our business.
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free, no hassle quote. |
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Blow Molding |
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PROCESS |
Similar to injection molding except
hot liquid plastic comes out of the barrel vertically, in a hollow
molten tube or "parison". The 2 halves of the mold close on it and
compressed air blows up the parison like a balloon, forcing it
outward to conform to the inside shape of the mold. After cooling,
a hollow part emerges. |
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RAW MATERIALS |
Most commodity grade and engineering
grade resins may be blow molded. However, the "melt index", or
viscosity, of the plastic must be high to keep the parison from
stretching too much prior to mold closure. The resin is in the
form of pellets before processing. |
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TOOLING |
Machined or cast aluminum is
traditional. |
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COST |
Part prices are generally higher
than injection molded parts, but lower than rotationally molded
parts. Tooling costs are moderately expensive. |
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ADVANTAGES |
This process lends itself to any
designs involving hollow shapes. Equipment availability is good in
most geographical locations. Can save tooling dollars over
injection molding. |
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DISADVANTAGES |
Cycle times are slower than
injection molding. Piece prices are higher than injection molding. |
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EXAMPLES |
All types of bottles, toys, air
ducts for automobiles, chemical & gasoline tanks, household goods. |
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CLICK HERE
for summaries of the
most widely used Plastic Processing Methods |
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