Rotational Molding Services

Rotational Molding Services | Undercuts | undercut

Rotational molding services from Gregstrom mean plastic parts in a wide variety of shapes, sizes, textures, and colors with features such as undercuts, multiple walls, and molded-in hardware and graphics. Ask Gregstrom about roto molding services for your next plastics project.

Rotational molding services create hollow plastic parts according to your precise specifications, and with low tooling costs and value-added post-mold services. With our roto molding services, powder or resin is loaded into a hollow mold which then rotates on two axes inside an oven until the inside of the mold is coated uniformly. After the mold is cooled, the hollow plastic part is removed.

Advantages of Rotational Molding Services

With its low tooling costs and quick tooling modifications, rotational molding – a process also known as rotomolding or rotocasting – is ideal for prototyping and for both low and higher volume production runs. Rotomolding tooling ranges from simple two-piece sheet metal molds to multi-piece aluminum molds with articulating features.

Rotomolding is flexible enough for projects ranging from small, intricate designs to large, complex parts and assemblies. Many rotomolded shapes are impossible to produce by other methods. Moreover, because there’s no pressure in the rotational molding process, hardware made of various materials can be molded-in for strength and durability. Other plastics molding processes just can’t support molded-in hardware like rotomolding can.

Rotational molding also supports a wide variety of surface textures and colors. Rotocasting or rotomolding even supports uniform walls without the thinning in the extremities that’s common to other processes. Designers like how Gregstrom can create rotomolded parts with undercuts and multiple walls, too. Rotationally molded parts can also be filled with polyurethane foam for added strength or insulation.

Molded In Graphics and Roto Molding Services

Custom rotomolded parts from Gregstrom can feature Mold In Graphics, a permanent way to mark, decorate, brand, or label your plastic parts. Traditional stickers and labels don’t adhere well to plastic materials, and some require spray adhesives. Mold In Graphics supports permanent labeling, branding, and marking while also providing better resistance to UV, weather, and chemicals.

Applications for Rotational Molding Services

Gregstrom can create many different types of custom rotomolded parts. Examples from our roto molding services portfolio include:

They also include:

  • Boats
  • Spine Boards
  • Baby Changing Stations
  • Lawn/Garden Equipment Housings
  • Printer Housings
  • Parts Washers
  • Water Treatments Tanks

For more examples of our rotomolding services, see the Chemical Feeder and the Heineken Draught Keg Cooler in our Featured Projects.

Production Equipment for Roto Molding Services

Rotational Molding ServicesGregstrom uses Ferry Rotospeed RS-220 and RS2-3300 machines to manufacture your custom rotomolded parts. Each machine has offset arms, and the largest machine has up to 125” swing.  This means we can rotomold plastic parts in a wide ranges of sizes and shapes from intricate spray manifolds to small boats.

Auxiliary Equipment for Roto Molding Services: High-Intensity Mixing

Gregstrom’s auxiliary equipment for rotomolding includes a Ribbon/Paddle Blender with a 1000-lb. capacity. Our newest machine, a high-intensity mixer with a capacity of 300 lbs., provides even faster mixing cycles and features an optimized vortex for heat generation and shear to avoid agglomeration of the mix material. This new machine “polishes” the resin, which means more uniform colors, reduced porosity and improved overall physical properties.

Auxiliary Equipment for Roto Molding Services: Polyurethane Foam Filling

Rotational Molding ServicesGregstrom also has the equipment and expertise to fill your custom rotomolded parts with polyurethane foam, which provides additional rigidity and thermal insulation. Because rotomolded parts (such as coolers) have hollow cavities, their design is optimal for filling with PU foam.

Rotational Molding Design

Rotational molding design has three basic requirements. First, the plastic part must meet the application’s end-use or functional requirements. Second, the design of the part must account for any limitations that are related to materials or processing. Third, the rotomolded part must be cost-effective to produce.

For design engineers, the details of a part’s design can mean the difference between success and failure. Typically, these details include:

  • Nominal wall thickness
  • Wall thickness uniformity
  • Varying wall thickness
  • Flatness considerations
  • Minimum wall separation
  • Corner angle limits
  • Reinforcing ribs
  • Kiss off ribbing
  • Draft angles
  • Corner Radiuses
  • Undercuts
  • Tolerances

Choose Rotational Molding Services You Can Count On

For nearly 70 years, Gregstrom Corporation has been forming and molding plastics at our Made in the USA manufacturing facilities in Massachusetts. To learn how our plastic contract manufacturing services  can add value to your application, contact us on-line or call (781) 935-6600.