Plastic Manufacturing Guide

Plastic Materials: Pellets, Resins, and Powders

Choosing the right material for your parts is critical to their functionality and longevity. Beyond pellets, resins, and powders, it also makes sense to mention solid-form plastics, which come in blocks and cylinders, for use in CNC machining. More about those later.

There are two types of plastics: thermosets and thermoplastics.

You can always remember the difference because the end-form of a thermoset part is, well, set. You can’t melt it and use the goo to reform another part. It’s one and done. Generally, thermoset plastics require less heat and pressure to form, but also have high heat and chemical resistance. On the downside, they tend to be non-recyclable.

Thermoplastics are the opposite; while they are built the same way, typically they can be returned to a liquid form and remolded. That said, you do need more heat and pressure to form them into parts. The properties of the parts you get will vary depending on the material you’ve chosen.

Both plastics can be found across the manufacturing ecosystem taking unique journeys to final part based on your chosen service line. If you’re designing medical parts, you have a lot of requirements to adhere to, so you may want to explore some of the more popular plastic materials at a deeper level.

Starting with 3D printing, stereolithography (SLA) uses an ultraviolet laser to cure thermoset resin. When using selective laser sintering (SLS), thermoset and thermoplastic powders are solidified with the zap of a laser. Multi Jet Fusion (MJF) sprays fusing/detailing agents just like an inkjet printer to build out parts layer-by-layer, setting layers of powder as the build progresses.

Injection molding, for example, is more straightforward. You will work with either thermoset or thermoplastic pellets, which are melted into liquid resin so they can easily flow into, and through, a mold. The service also boasts the largest library of plastics.