Thermoset Molding Processes

As a moldable plastic composite, thermosets can be molded in similar molding processes as thermoplastics such as nylon, ABS, and polypropylene. They can be injection molded, compression molded, and transfer molded. Each molding process offers different benefits and disadvantages depending on the finished part’s geometry, assembly, and commercial aspects of the program. OEMs and molders must take into consideration all variables of a part and how it is used to determine the best molding process to make the part. While there may be multiple molding processes that can successfully produce the part, some processes may be more advantageous based on pricing or quality specifications.

Injection Process

Using an injection molding process is very common in many industries for thermoset components. Thermoset injection molding process offers a fast cycle time compared to a compression or transfer molding process, allowing a molder to produce a higher throughput of production in a day or shift with an injection process. Industries such as automotive, electrical, and home appliance markets rely on injection molding process for thermoset components that need to be produced in high quantities and shipped to customer plants quickly. An injection molding process may save as much as 50% of machine time over a production run with a faster cycle time compared to a compression molding process. Designing a thermoset part to be produced with an injection process allows for design flexibility with the ability to move parting lines, gate locations, and ejector pins to preferred locations of a part. Molders are also able to run injection molds automatic without the need for an operator at the press to demold and feed material to the press. Because of these economies of scale, injection molding is a very common process type that allows molders and OEMs to produce a high number of parts at the lowest cost to manufacture.

Compression Process

Some applications may require additional material strength over an injection process. Compression molding offers the highest strength molding process for finished parts. Depending on an product application’s requirements, an injection molding process may not offer the needed strength characteristics for a finished part and the part will need to be compression molded. Compression molding also eliminates gating for parts, as material is placed directly into the mold instead of using a runner system to feed parts with material. The drawback for compression molding vs injection molding is a more costly, laborious process that is only necessary if a part cannot achieve the end characteristics with an injection molded part.