Rotational Molding / RotoMolding

Alternative means to plastic injection molding

What Is Rotational 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.



ASH Injection Molding Benefits

  • State-of-the-art Equipment
  • Experts in the roto molding process
  • Strict Quality Checks & Control
  • Customer Focused Staff
  • Made in America

Why Use ASH Industries for  RotoMolding & Manufacturing?

ASH has been in the manufacturing & engineering business for over 30 years, which gives us tremendous depth, experience & knowledge about molding. In our time helping clients with creating products and parts we've seen and done it all. Experience & expertise is important when it comes to manufacturing products - ASH can offer you deep insights into the best way to utilize the roto molding process for your product to save you time, money and achieve success.

New Technologies & Capabilities:  ASH is constantly updating and evolving our manufacturing processes, developing new techniques for thermoplastic injection molding, medical injection molding, rotational molding, silicone liquid injection molding that save you time and money bringing your product to market. Our innovative rotational molding techniques mean you get quality, low cost parts and a quick time to market. We also have some of the best rotomolding machines and equipment.

Made in America: ASH® is proud to do all our roto molding manufacturing in America, no outsourcing. Every point of our process is done right here in the USA, at our product manufacturing facility in Louisiana. We work with clients all over the United States and can ship products nationally and globally. 

Experienced Engineers & Project Managers: Our rotational molding engineers have vast experience in manufacturing and helping customers bring their idea or product to fruition. We work hand in hand with you and ask all the right questions to give you the tools your product needs to succeed and do the job you designed it for in targeted environments.


pic-limRotational Molding Manufacturing Process

Rotational molding is a unique manufacturing process in that it can make hollow products such as kayaks, flotational devices, rotomolded coolers and more. Conditions and configurations can be changed on the fly with multiple parts being able to be rotationally molded in the machine. How does rotomolding work? Pelletized material is turned into a dust and put in a mold, which is then rotated inside a massive oven, heating and melting the plastic to coat the inside of the mold evenly.With Injection molds, we cut water lines in the steel and run water through the lines to pull the heat (energy) out of the plastic so it will harden. The molds come out of the oven and are cooled by either blowing air, misting water, or both. This process is generally great for large parts.


Advantages of Using Rotational Molding

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

  • Cost effective: Rotomolding is a cost-effective production process. Manufacturing costs to create the mold are comparatively lower than other plastic production processes and tooling costs are also affordable.
  • 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.
  • pic-kayakNo 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.


Limitations of Rotomolding

Rotomolder:  rotomolding machineAs we previously mentioned, every part production process has its shares of pros and cons. While we already listed the pros in the above section, rotational molding 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 for Rotational Molding

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.


Materials Used in Rotational Molding

pic-processPolyethylene 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
  • 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.


ASH™ is Trusted for RotoMolding Made in America

ASH® is a rotational molding company that is focused 100% on the success of your rotomolding project. It doesn't matter if you are a Fortune 500 company that needs to mass produce a part for your new medical device or an entrepreneur looking for help with producing & developing your prototype product, ASH can help you achieve success. One of ASH's core tenants is hiring the best people in our industry, right here in America. We hire people who truly love what they do, listen to the customer and are passionate about creating the best product possible.

Engineers at ASH Industries™ understand the complexities of beginning a new rotomolding project and want to help you to bring yours to fruition. You can trust the experts at ASH to take your product from concept to completion.

For more information on ASH™ roto molding and if it would be the right method for your part run, contact one of our manufacturing & engineering experts now.




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. 

Connect with ASH®

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

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