Thin & Hollow: Plastic Blow Molding
This is one of the most common form of molding hollow objects to produce plastic products ranging from small bottle of water to large cylinder tank. But sometimes, it could also be applied to glass as well.
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The process involves an extruded preform, or a ‘hot melted plastic drip’ as I call it, down in between a two-part mold. Eventually, these two halves of the mold will close, which would seal tight the bottom of this ‘drip’, meanwhile leaving the top open for air access. As the air is being pumped into the sealed two-part mole (think of it as inflating a balloon inside a hollow parts of a pair of sandwiches) the plastic ‘drip’ will expand in accordingly with the desired internal contour of the mold. Once the plastic cool and hardens, the two halves of the mold will open, and any excess plastic sticking out the top or the bottom will be trimmed off.
Besides of having the advantage of low cost, fast produced and highly detailed texture. Plastic blow molding also has drawbacks in terms of its high tooling cost, limitation in basic form and requires large volume in order for each single unit to be cost effective.
