How Is a Rotational Molding Made?
Rotational molding is a production method used primarily to make plastic hollow items such as canoes, trash cans and children's toys. Popular because it is a relatively inexpensive method of molding that requires a short amount of time, rotational molding is also referred to as rotomolding or spin casting. High temperatures and rotation allow the material inside the mold to spread and set evenly. While rotational molding is an efficient production method, it does require an operator to properly monitor the production process; overheating and under-heating can contribute to a lackluster final product.
Other People Are Reading
Instructions
-
-
1
Pour a premeasured amount of polymer powder into the mold at the rotational molding machine's load/unload station. Place the cover of the mold securely on top of the mold and lock or bolt the top into place.
-
2
Put the mold into the rotational molding machine's oven and turn on the oven, ensuring that the timer is set for the specific mold being made. Once the oven is turned on, it will simultaneously produce heat, rotating both vertically and horizontally. The rotation of the oven prevents the polymer from accumulating in any one section of the mold because the the polymer is constantly moving and being spread over the entire mold. Once the polymer reaches a heat breaking point it begins to attach to the walls of the mold.
-
-
3
Remove the mold from the rotational molding machine promptly and not prematurely. If the mold is overheated the polymer degrades, while under-heating the mold causes bubbles to appear in the finish due to the polymer having an inadequate amount of time to adhere to the mold walls. Rotational molding requires the operator of the machine to pay attention to the production process, as the improper removal of the mold from the oven can change the mechanical properties of the polymer and negatively affect the appearance or strength of the final product.
-
4
Place the mold on a cooling station, open the top and remove the finished product. Each finished item must be cooled for at least 10 minutes (possibly more) to allow the polymer to strengthen. The rotational molding machine operator must monitor the cooling process because fast cooling can cause the final finish to warp.
-
1
Tips & Warnings
Post-production work, such as trimming, must take place after all molding has been completed (some products require additional/secondary time in the oven) and after cooling has allowed the polymer to harden and set.
References
Resources
- Photo Credit Hemera Technologies/PhotoObjects.net/Getty Images
