What is Plastic Rotational Molding?

Rotational molding is a process for manufacturing hollow plastic products.  The process consists of introducing a known amount of plastic (in powder, granular, or liquid form) poured into a hollow, shell-like mold.  The mold is rotated about on two principal axes at relatively low speeds as it is heated so that as the plastic melts it adheres to the mold surface.  The mold rotation will continue during the cooling phase as well so that the plastic retains the desired shape as it solidifies.  Once the mold has cooled, the part can be “demolded” and any secondary work such as trimming/assembling can take place.

Rotational Molding has several benefits including the ability to produce thicker walled parts than blow or injection molding by simply increasing the amount of resin introduced to the mold. Another advantage of rotational molding is the molds/tools are much more economical to produce than blow or injection mold tooling. One disadvantage of rotational molding is the time necessary to produce parts which lends itself to components with lower estimated annual units (EAU’s).

Stern Companies Incorporated (SCI) produces rotationally molded plastic products in our 50,000 sq. ft. production facility located in Brainerd, MN.  We currently run four Ferry RotoSpeed machines in our facility 5 days a week / 24 hours a day.  Industries we support are in the agriculture, recreational, marine, waterworks, snow removal, as well as a variety of other industries.  We have engineers on staff to help answer questions you may have regarding your roto-molded project.

SCI has a full assembly shop as well with the ability to procure and assemble components to customer specifications.  SCI is ISO 9001 certified and has a strong supplier base providing customers with quality product, delivered on time, at the lowest achievable cost.  Contact us today and let us help you with your next rotationally molded project!