Rotational molding process pdf

In order to maintain even thickness throughout the part, the mold continues to rotate at all times during the heating phase and to avoid sagging or deformation also during the cooling phase. The process was applied to plastics in the 1940s but in the early rotational molding process pdf was little used because it was a slow process restricted to a small number of plastics. Over the past two decades, improvements in process control and developments with plastic powders have resulted in a significant increase in usage.

Peters of Britain documented the first use of biaxial rotation and heat. The main purpose of using rotational molding was to create consistency in wall thickness and density. In 1905 in the United States F. Voelke used this method for the hollowing of wax objects. Perks’s process of making hollow chocolate eggs in 1910.

Rotational molding developed further and R. These early methods using different materials directed the advancements in the way rotational molding is used today with plastics. Plastics were introduced to the rotational molding process in the early 1950s. One of the first applications was to manufacture doll heads. The machinery was made of an E Blue box-oven machine, inspired by a General Motors rear axle, powered by an external electric motor and heated by floor-mounted gas burners. The cooling method consisted of placing the mold into cold water.