roto-moldingOne of the most common types of molding we do at Advanced Packaging is rotational molding, also known as roto-molding. Roto-molding uses heat and bi-axel rotation to create hollow individual pieces that are later assembled into the finished case. Roto-molding is quick and allows inexpensive mass production of customized cases without requiring a lot of startup money. But how is it done? Advanced Packaging is here with the scoop on exactly how roto-molding works.

Release Agent Application

To ensure that the finished part is cleanly ejected from the mold without leaving behind excess plastic or damaging the part, roto-mold technicians must first coat the mold with a release agent. Release agents are available in one-use, semi-permanent, and permanent coatings. Semi-permanent coatings are most often used, must be reapplied after every few uses, and are typically made from a polysiloxane.


Roto-molding starts by loading a pre-measured amount of plastic polymer, often in a powdered form, into the molding chamber. The mold is then sealed to prevent leakage and preserve part integrity.


The mold is then simultaneously rotated and heated until the plastic polymer melts and sticks to the mold wall. The central, hollow portion is rotated on multiple axis at different speeds to avoid polymer accumulation. During roto-molding, it’s important to time the heating process exactly. Heat for too long and the polymer will degrade resulting in a weaker finished product. Heat it too little, and the polymer melt will be incomplete, resulting in a misshapen part with bubbles of unheated polymer particles along the surface.


Typically done with an industrial fan, the mold must be cooled so that your roto-molded part can be safely removed. This usually takes 20+ minutes, during which the part will shrink, slowly detaching from the mold for easy removal. Cooling must be done gradually however, as rapid cooling of roto-molded products can sometimes warp and damage parts.

At Advanced Packaging, We Know Our Stuff.

If you’re looking for roto-molded cases made by industry professionals who have a deep understanding and respect for the technology they wield, then call Advanced Packaging today. Advanced Packaging, Inc. was established over 40 years ago with the mission of engineering and delivering the highest quality shipping and cushioning systems available.

Since then our worldwide customer base has grown to include those in the military, government, commercial and industrial business sectors, as well as many other industries. API’s local clients value our convenience to the Washington, DC tech corridor.

Not only do we make custom cases for every type of industry, API is also equipped with the latest in quality assurance and process control monitoring technology, including drop testing, protecting your electronic equipment from unforeseen accidents and events. Our team of craftsmen regularly build and then test a variety complex electronic assemblies.

If you have any questions, please contact Advanced Packaging Inc. by calling 1-888-206-5250 or visit our website today!

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