Rotational molding, also known as rotomolding, offers many manufacturing benefits. The process, invented in the 1850s, proved an effective way to produce a wide range of hollow goods from artillery shells to chocolate Easter eggs.
Rotomolding plastics began in the 1950s. The technique “revolutionized the production of hollow plastic products,” according to this post in The Manufacturer. With many benefits over other production methods, rotomolding continues to be a growing business. Research Nester values the market at $5.32 billion in 2023 and projects it to reach $11.77 billion by the end of 2036.
How Does Rotational Molding Work?
Rotomolding uses heat, gravity, and centrifugal force to form hollow plastic parts. The process does this by rotating a mold along two perpendicular axes. Rotational molding consists of four primary stages.
- Loading: This is where the powdered plastic resin is loaded into preheated molds.
- Heating: The constantly rotating molds are moved into an oven. Once fully heated, the plastic resin melts, evenly coating all sides of the mold.
- Cooling: Once the desired shape is formed the rotating molds move to a cooling area. The molds keep rotating until the plastic is fully cool and solid.
- Unloading: The finished product is removed from the molds.
Rotomolding works well on a variety of plastics, polymers, and coatings including Plastisol, Polyethylene, Nylon, and more.
Rotomolding Benefits
The rotational molding process offers many advantages to companies looking to create custom goods. According to the Association of Rotational Molders these benefits include lower cost tooling. This makes the process more affordable than other manufacturing methods. The cost benefit also helps companies looking to manufacture smaller quantiles of goods.
Rotomolding works to make virtually any size, shape, and color product. In fact, if a something is made of hollow plastic, it was probably rotomolded. That includes ping pong balls, store mannequins, industrial storage tanks, automotive parts, traffic cones, bins and bulk containers, even baby cribs and kayaks.
The process creates reliably even wall thickness, even at the corners. This makes rotomolded goods incredibly strong and resilient. Complex shapes with molded handles, graphics, threads, and inserts can be incorporated into the initial design. This saves companies even more time and money as it eliminates the need to invest in a second process to finish the piece.
Rotomolding Suppliers and Kaivac
Rotomolding companies can be found throughout the United States. Part of the light industrial sector, these businesses manufacture common and specialty plastic goods for everyday and specialty use. Expert Roto Molding, a Division of Kaivac®, has been creating high-quality rotomolded products in Clermont County, Ohio since 1969.
Kaivac, makers of innovative cleaning machines, partnered with the family-owned business early on. The company was the primary vendor for the plastic body parts found on all Kaivac systems. In 2022 Kaivac acquired the rotomolding company, bringing a large part of its supply chain in house.
As a division of Kaivac, Expert Roto Molding will continue to serve their customer base while benefiting from their parent company’s management expertise. “The unification of our companies will enhance each other,” says Kaivac CEO Bob Robinson Sr.
Click here to learn more about Expert Roto Molding.