Are you comparing plastic injection molding vs. rotational molding for your next project? Both processes have their advantages, but what’s the best choice for your application? Read this article to compare these two processes and then contact Gregstrom Corporation if you decide that rotational molding is what you need. In addition to rotomolded parts, we provide value-added services such as design assistance, plastics finishing, quality assurance, and product assembly.
Plastic Injection Molding
Plastic injection molding is a manufacturing process that molds parts from plastic pellets that come in various materials. The pellets are melted and then injected into a closed cavity via hydraulic pressure. Typically, the tooling is made of either stainless steel or aluminum. Stainless steel injection molds support greater volumes of parts across more cycles, but they’re expensive. That’s why plastic injection molding with stainless steeling tooling is generally reserved for high-volume production.
Although injection molded parts can be made of colored plastics, cost considerations may require the use of paintings or coatings instead. Textured tooling can produce textured parts, but this type of mold finishing adds significant expense to a stainless steel tool. Also, the quality of the injection mold determines the number and extent of post-molding defects such as flashing, warping, bubbling. Sink marks and ejector marks with plastic injection molding can also mar part finish.
Rotational molding produces strong, hollow plastic parts in a variety of materials, shapes, and sizes. Powder or resin is loaded into a hollow mold which then rotates on two axes inside an oven until the inside of the mold is coated uniformly. After the mold is cooled, the plastic part is removed. Unlike plastic injection molding, there’s no pressure in this process. Rotomolding also supports the creation of shapes and features, such as undercuts, that are impossible to achieve with other manufacturing methods.
Importantly, the tooling that is used with rotational molding costs less. Consequently, rotomolding is suitable for prototypes as well as both lower and higher volume production. Unlike other processes, rotomolding also supports uniform walls without thinning of the extremities. Rotomolders can use colored plastics, produce textured parts, and support molded-in hardware and Mold In Graphics. Plastics finishing can be achieved with CNC routing or the use of an industrial robot.
Are you ready to discuss rotational molding for your next plastics project? Contact Gregstrom.