Rotomolding, short for rotational molding, is a process for manufacturing durable plastic parts for many markets. A heated hollow mold is filled with material. It is then rotated, causing the softened material to disperse and stick to the walls of the mold. In order to maintain even thickness throughout the part, the mold continues to rotate at all times during the heating and cooling phases.

There are many advantages to the rotational molding process. Tooling cost is much lower, which often makes rotomolding a more cost effective method, especially for smaller quantities. The process has virtually no size limitations and parts are produced with an even wall thickness, even at the corners. Complex shapes with molded in handles, graphics, threads, and inserts can all be part of the design, saving you time and money by eliminating secondary operations.

ARM has developed this additional document for companies who plan to begin rotomolding.

Rotomolded parts are found in industries ranging from recreational to medical to automotive. See our Design Applications below for a quick look at some amazing parts.

• Bird FigurineFigurine is made of semi-rigid PVC with extreme undercuts. The part is air brushed and filled with a cement-foam mixture post molding.

• Water FiltrationWater filtration unit has a complex design with 132 kiss-offs, molded through holes, and is stackable.

• POP DisplayPoint-of-Purchase display features durable one-piece construction with an add-on drip tray.

• Cymbal CaseCymbal case is lightweight for ease of carrying yet rugged construction protects contents.

• Double-wall FoamDouble-wall part with foam insulation produced during the molding process results in superior strength, increased insulation, and close tolerances.

• Traffic SignTraffic sign is molded as a seamless, single piece part with two different colored resins.

• Vehicle Crash BarsVehicle crash bars converted from metal are lighter weight yet still provide adequate protection in minor collisions.

• Medical CaseMedical specimen case is insulated to protect contents.

• Used Coolant Reservoir TankUsed coolant reservoir tank has a complex shape that lends necessary strength to the part. Due to its complex shape, this part could only be produced by rotomolding.

• Floor SweeperFloor sweeper frame combined 120 metal parts into one rotomolded part, reducing assembly time and increasing product integrity and durability.

• Blower HousingBlower housing with threads and inserts is made from a flame-retardant polyethylene.

• Inflatable Oxygen MasksInflatable oxygen mask seal is made of PVC and provides flexibility for patient comfort.