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D � S <br />Q ri <br />iHN <br />H M <br />KH.�ro <br />y�dy <br />O0 <br />Hmg <br />CH <br />H H <br />gEa <br />O W <br />In <br />C' <br />�ftmft, <br />U"I <br />ROTATIONAL MOLDING <br />THE THREE -STAGE PROCESS: <br />i Loading resin In the mold <br />THE PROCESS <br />BIAXIAL POTATION <br />2 Heating and fusion of resin <br />The process is simple in con- <br />cept. Heat Is used to melt <br />and fuse a plastic resin in a <br />closed mold. Unlike most <br />other plastic processes, no <br />pressure is Involved. The <br />three -stage process Includes <br />loading the resin in the mold, <br />heating and fusion of the <br />resin and cooling and unlcad- <br />ing the mold. <br />NEA� <br />WATEAIAIR <br />91 AXIAL ROTATION <br />WW AT�. <br />fI <br />a Cooling prior to unloading mold <br />After the charged mold is <br />moved into an oven, the mold <br />is generally rotated on two <br />axes at low speed. As heat <br />penetrates the mold, the <br />resin adheres to the mold's <br />Inner surface until it Is com- <br />pletely fused. The mold Is <br />then cooled by air or water <br />spray or a combination of <br />both while still rotating, <br />lowering the temperature In <br />a gradual manner. The mold <br />is opened, finished part re" <br />moved and mold rechoged <br />for the next cycle. <br />A variety of materials is <br />available. The most widely <br />used are polyethylenes and <br />plastisols. Other materials in- <br />clude nylon, fluoropolymers, <br />polypropylene, polycarbonate, <br />cellulose acetate butyrate, <br />elastomers, polyurethane, <br />and EVA. <br />