We carry a selection of thermoplastic resins that are suitable for use with our benchtop injection molders, including:

  • Low Density Polyethylene (LDPE)
  • High Density Polyethylene (HDPE)
  • Polypropylene (PP)
  • Polystyrene (PS)
  • High impact polystyrene (HIPS)

FAQ: Are other types of plastics suitable?

Yes. Our machines are capable of injecting other types of plastics (a/k/a resins). However, keep in mind, for every type of plastic (e.g. PE, PS, PP, PLA, TPE, etc.), there are often numerous GRADES (i.e. formula variations) on the market to choose from, which can vary greatly in their processing requirements. So, some grades of a particular “type” of plastic may inject well, and other grades not so well, or at all.

When evaluating if a particular resin is suitable, it’s important to make sure its required processing temperature is within the capability of the benchtop molder (i.e. 600 F max.). Another important consideration its melt flow rating (MFR), which is a numerical measurement (e.g. 20g/10 min. @ 2.16 Kg) of how easily it flows under pressure when molten. Grades that are formulated to have a high MFR usually work best in our hand-operated machines because less injection force is required to make them flow. Another determining factor is the size and shape of the part you want to inject. In other words, one particular grade of plastic may flow well enough to inject a small part with simple geometry, but not flow well enough to completely fill the mold cavity of a larger part with many intricate pathways. Resin manufacturers will often carry a range of grades for each type of plastic they sell. So, if one grade doesn’t flow well enough to make your part, you may be able to find a similar grade that flows better, offered by that same manufacturer. The downside of selecting a grade with a higher melt flow rating (MFR), is that the plastic may exhibit a decrease in certain physical attributes, such as its strength, rigidity, toughness, etc. So, it’s often a trade-off, finding a grade that flows well enough to make your part, but still has the physical characteristics you require in the finished part. Another thing to be aware of is that some types of plastics are also inherently more difficult to inject than others. So, what is considered “high flow” for one TYPE of plastic might still not flow nearly as well as a “high flow” grade of another TYPE of plastic. The website has a large database of technical info and specifications for many different resins on the market.

Here’s an article by SpecialChem SA describing the technical aspects of melt flow rating (MFR) in great detail.