Putting The Right Spin On Rotational-Molding Designs

New developments let rotational molding compete with injection or blow molding. Computer-generated color renderings help rotational molders finalize designs. The use of 3D models boosts productivity and helps create drawing views and cross sections that simplify the job of building patterns. A premeasured amount of powdered or liquid plastic is placed in mold half. The mold is closed, transferred to the heating oven, and then on to the cooling station. During the entire heating and cooling process, the molds simultaneously rotate around two right-angle axes. Typical carousel rotationalmolding machine with three arms that rotate between loading/unloading stations, heating ovens, and cooling chambers. Kiss-offs increase part stiffness. They are used individually or in a series or pattern and will outperform ribs in many cases. The almost kiss-off gives nearly the same structural strength without adding a blemish on the outside wall. Rotationally molded newspaper boxes manufactured by Steel City, Youngstown, Ohio, unlike their metal counterparts retain their good looks (no chipped paint or scratches), remain rust free, and are nearly dingproof. Rotational molding gives a portable fuel tank a heavy-duty handle which provides good load control and a secure grip. Made by Tempo Products, Cleveland, the tanks have a 29-gallon capacity and are color coded for different fuel. Football enthusiasts now sit on rotationally molded bench seats. Designed by Dant Clayton Corp., Louisville, Ky., the plastic seats were installed in 1999 in the Citrus Bowl, Orlando, Fla. Normally with a volume requirement of 65,000 one would consider the blow-molding process. But the project required seven different sized seats each in three different colors. The blow-mold tooling would have been more expensive and the production runs for each size/color combination would have been small for the blow-molding process. Rotationally molded products are a good fit for a wide range of industries. Production runs