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Introduction:
Rotational molding is a method of casting hollow plastic parts with few restrictions regarding size or complexity. This type of molding allows for the manufacturing of large and small hollow parts that are integral and seamless. Rotational molding can replace metal fabrication, laid up fiberglass, wood and other plastic processes. The technique is applicable to most thermoplastics but is most widely used with polyethylene.
Process:
Hollow molds are filled with powdered plastic and secured to pipe-like spokes which extend from a central hub.. The molds rotate on two separate axes at once. The hub swings the entire mold into an enclosed furnace room which causes the powder to melt and stick to the insides of the molds. With the molds still rotating slowly, it swings into a cooling room where sprayed water causes the plastic to harden into a hollow part.
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