Rotational Molding

Rotational molding, also known as rotomolding, loads pre-measured plastic resin into molds that are moved to an oven where they are slowly rotated on both a vertical and horizontal axis. Hollow molds filled with powdered plastic are secured to pipe-like spokes that extend from a central hub. The molds rotate or tumble on separate axes at once. The hub swings the entire mold into an enclosed furnace room that causes the powder to melt and stick to the insides of the tools. The melting resin sticks to the hot mold and coats each surface evenly. During the cooling cycle of rotational molding, the mold continues to rotate so that parts retain an even wall thickness. With the molds still tumbling slowly, the tools swing into a cooling room where sprayed water causes the material to harden into a hollow part. When the parts are cooled, they are released from the mold. The rotational speed, heating times, and cooling times are controlled throughout the entire process.