Rotational Molding Icon
Primary benefits include:
  • High-quality appearance
  • Stress-free parts
  • Lower tooling costs than other molding processes
  • Quick to market
  • Small to very large parts
  • Secondary Machining is available to produce tighter tolerances

What is Rotational Molding?

Rotational molding, also known as rotomolding, is a plastic molding process that uses rotation and gravity, rather than pressure, to mold parts and components. The molds are heated while being rotated on two perpendicular axes. This disperses the material and fills the mold.

The parts produced are hollow and the wall thicknesses can vary throughout the part from 0.100” to 0.320”

The process offers numerous design possibilities. Complex geometries can be created. This versatility means products that previously required many components can be made with fewer parts using rotational molding.

Rotomolding has many benefits. The hollow parts can be filled with a plastic foam for greater strength and buoyancy. Molded-in inserts can be used. Plus many other secondary operations can be used for added value.

Because no pressure is used, the molds are less complex than injection molding tools. Plus, molds can often be made with less expensive materials such as cast aluminum. Together these save on tooling costs and lead times.

Rotational molding is used for a wide range of parts and in a variety of industries. Small to very large parts can be molded. The process produces attractive surface finishes with excellent detail.

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The benefits of rotomolding

Every plastic molding process has its advantages. Miles Products and our production partners can advise on the process that is best for your program. The most valuable resource we offer is a highly-trained, experienced and dedicated staff. Advanced facilities allow the team to deliver at the highest standards customers expect. This commitment to quality has grown into one of the top rotational molding services in the USA.

We specialize in:

  • Commercial Vehicles and Agricultural Equipment
  • Medical Equipment and Devices
  • Commercial Vehicles and Agricultural Equipment
  • Consumer & Commercial Lawn, Garden and Construction Products
  • Material Handling and Other Industrial Markets
  • Retail, Display & Point-of-Sale Units
Design benefits of rotational molding products:
  • Greater options and flexibility in part design
  • Produces parts with attractive finish plus excellent performance
  • Complex geometries in a single seamless part are achievable
  • Design can include double walls for excellent strength to weight ratio
  • Urethane foam filler can be used with hollow parts for excellent strength and rigidity
  • Thicker walls and/or added thickness to outer corners can be used for additional strength
  • Molded-in graphics, metal inserts, reinforcing ribs, kiss-off ribbing and undercuts can be used
  • One-piece design with complex shapes can eliminate post-molding assembly work
Production benefits of rotational molding products:
  • Suitable for small or very large parts. From several inches to 10 feet in width.
  • Accommodates low to high volume runs. Annual volumes up to 50,000 pieces.
  • Ideal for hollow, enclosed or parts with openings.
  • Faster tooling times can get products to market quicker.
  • Nearly stress-free parts because no pressure is used.
  • Produces very uniform cross-sections with minimal or no warpage.
  • Uniformity of wall thickness can be maintained to within ±10 percent.
  • Much higher tolerances compared to other molding processes.
  • Excellent aesthetic finish and surface detail.
Cost benefits of rotational molding products:
  • Complex, hollow, seamless, one-piece geometries can produce parts other processes can’t achieve and at a lower cost.
  • Mold simplicity and the option to use less expensive materials such as aluminum reduces tooling costs.
  • Families of molds and the capability to run multiple molds simultaneously allows for more cost effective production.
  • Unique design flexibility can eliminate secondary assembly.
  • Multiple parts can be molded as one reducing both part and tooling cost.
  • Use of polyethylene resin material can reduce costs even more.

We carefully plan to consistently provide

Precision-made parts & assemblies

Unmatched value

On-time delivery, month after month, year on year

A trustworthy supply partner

  • ISO 9001:2015 Certified Quality Standards.
  • 286,000 sq. ft. state-of-the-art facilities with 11 molding machines and 5 CNC routers.
  • A commitment and history to continuous improvement using MRP, JIT and Kanban to consistently deliver.
  • The latest IRT technology of infrared sensors to monitor temperatures during molding.
  • Use of Rotolog and EZ Logger sensors inside the mold for further monitoring and optimization.
  • Two facilities with one plant dedicated to high volume work.

In-house engineers and technical staff can work with your team to see the project from concept through design and tooling. This helps ensure a smooth production and beautifully molded finished parts.

  • Experts in product development, material specification, tooling, molding and lean manufacturing.
  • Dedicated project management throughout the entire project using Advanced Product Quality Planning.
  • Tooling engineering and tool building management.
  • Dependable USA-based tooling resources.
  • Design for Manufacturability Specialists.
  • SolidWorks CAD capabilities
  • Finite Element Analysis (FEA)

Quality control is a central component of our program. Our rotomolding services were one of the first in the industry to achieve ISO registration.

Continual training and investment the latest technology support certified quality control staff.

Equipment used include Faro Arm CMM and BYK Gardner Color Measurement systems.

Highly trained project management and quality control personnel oversee your entire project through to shipping the finished parts and components to your facilities.

Resins are purchased directly from the manufacturers with final preparation and colorization of the materials done in-house.


High-pressure foaming machines with closed loop controls is just one of the many value-add operations that can improve your options and finished product.

Hollow parts are foam-filled to provide insulation, buoyancy and/or added strength with minimal extra part weight.

Polyurethane foaming is ideal for many applications including:

  • Refrigerator Doors, Insulated Panels and Cabinets
  • Flotation Devices
  • Ridged EMT Back-Boards

Great design, planning and production rely on precision-made tools.

Experienced staff with the newest technology oversee your entire tooling process.

Rotational molding tools are generally simpler in design compared to injection molding tools.

CAD software helps shorten lead times.

Secondary Operations and Assembly

Highly engineered parts are our specialty. This often relies on secondary operations from simple riveting to complex multiple part assemblies.

Our systems, staff and lean manufacturing make your complex parts simple


We use the most up-to-date technology and molding machines. Each runs IRT controls and is operated using a proprietary rotomolding ERP system.

The machines use five stations with independent arms to cycle from loading to oven, intermediate area, cooling station and unloading area. Each cart indexes on a central pivot post and shares a common load-bearing track.


The facilities have one of the highest ratios of routers-to-machines in the business. These deliver industry leading value-added secondary and assembly operations.

Routers include:

  • x2 Motionmaster 5-axis routers
  • x1 Quintax 5-axis router
  • x2 DMS 5-exis routers
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See how your products can benefit from rotational molding.