Rotational Molding / RotoMolding

Alternative means to plastic injection molding

Rotational Molding / RotoMolding

Why choose ASH for my Rotational Molding Needs?

  • State-of-the-art Equipment:
  • Focus on Timeliness
  • Strict Quality Checks
  • ASH Roto-XL Molding

Rotational molding, which is also commonly referred to as "rotomolding" or "rotational casting," is a common means of creating plastic parts that's increasingly gaining traction as an alternative means to plastic injection molding and other plastic producing processes. A big reason is because parts that are challenging or impossible to create via plastic injection molding, blow molding and thermoforming - such as hollow parts, partially enclosed parts, large and small parts and parts with other complexities - can be crafted via the process.


Rotomolding was actually invented in the 20th century, but didn't gain traction as a production process until the 1960s. Today, it continues to advance as a viable process for plastic part creation. Rotational molding machines create parts by rotating parts on an axis, which thereby force the plastic material to stick to the walls of the mold - hence why it's an ideal process for creating hollow parts.


The process uses resin powder, rather than plastic pellets. The resin then heats in the mold as it is being rotated. Unlike other plastic part producing processes, ASH™ Industries rotational molding can efficiently and affordably produce both short-run and long-run product runs.



Here's a look at some of the advantages of the rotomold process:

  • Cost effective: As we hinted at in the opening, rotomolding is a cost-effective production process. Up front costs to create the mold are comparatively lower than other plastic production processes and tooling costs are also affordable. Molds are typically lightweight and no cooling is necessary, either.
  • Effective for short runs: Many plastic production processes are best for long run part production. That's not the case with rotational molding. That's because the up front tooling costs and molding costs are cheaper than comparable methods, so you don't need to justify larger up front costs with longer part runs to get your money's worth.
  • No size limitations: Unlike other production process, there's a lot of part flexibility when it comes to rotational molding - both large and small parts can be made. Multiple cavity molds can also be used in production runs, which is advantageous. Containers and barrels are a common application of the process. To give you a better idea on the size range, consider that hollow barrels can be made ranging from 5 gallons to 22,000 gallons. That's a big part range.
  • Hollow part creation: As we noted in the opening, rotomolding is an ideal process for the creation of hollow materials, such as trash cans, construction barrels, storage tanks and containers, covers, housings, water softening tanks, battery cases and much more. But it can also be used to create parts that aren't hollow or aren't as hollow, such as under the hood automotive parts, surf boards, pool tables, cribs and children toys.
  • Eco-friendly: The process is eco-friendly, as only the material that needs to be used is used. There's no wasted material in the process.
  • Quality finish: Rotational molding also requires minimal post production part finishing, which also helps separate it from competing plastic production processes.


rotomolder rotomoldingAs we previously mentioned, every part production process has its shares of pros and cons. While we already listed the pros in the above section, rotomolding isn't without its share of disadvantages as well. For instance:

  • Long manufacturing times: There's a reason why rotomolding is comparatively cheaper than other production processes. And one of the reasons for this is that part runs generally take much longer to complete than these other such processes. So while using rotational molding is cheaper, you'll likely have to sacrifice time to market speed.
  • Material limitations: Not every plastic material can be used to create parts in the rotomolding process. Polyethylene is the most common.
  • Complexities: While parts are open to a lot of design freedom via the rotational molding process, the process sometimes struggles with some of the more intricate features, like ribs and undercuts.


Design Considerations

Our ASH™ rotational molding offers almost endless potential as far as design capabilities are concerned. For instance, the process can maintain uniform wall thicknesses better than other plastic parts. It also thrives at producing parts with double wall thicknesses and is ideal for molding thicker corners. Wall thicknesses and part piece weight can also be easily controlled via the process.

pic-processThe ASH™ Industries Process

Polyethylene is the most common plastic that is processed via rotomolding. However, the process has given way to several more materials recently. These include PVC, nylon, polypropylene and plastisols. One thing to keep in mind, however, as far as materials are concerned is that the process is one of the faster growing part production methods - so it's likely that engineers will incorporate more materials into the process as technology continues to advance.


For more information on rotational molding and to determine if the process is the right fabrication method for your next part run, contact ASH Industries Expert today.




About ASH Industries

ASH® Industries offers a wide range of product manufacturing solutions.

Our engineering knowledge, patience, technical expertise, and desire to please clients has led to consistent innovation. 

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1330 W. Willow St.
Lafayette, LA 70506 
Ph: (800) 598-5274 
Fax (337) 235-0971

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