Did we ever tell you that there are two main categories of Engineering Plastics? You probably knew already though or had heard something about it before, but as with everything else we try and bring you at Direct Plastics, we hope one day this just may come in handy.
Here’s the Bender
The first category are the benders and they’re called thermoplastics. What this basically means is that it thermally forms, plastics such as PVC and Acrylic (Perspex) are in this category as well as Nylon and even PEEK. You can bend them and once they’ve cooled, they take on their new shape; you can keep doing this many times over, although it has to be said, some thermoplastics are more suited than others
This second category is the thermoset’s, which means that they were set with heat during the manufacturing process and cannot be re-formed. Heat has no malleable effect and plastics such as Tufnol fall into this category
Why this may be important
While the thermoplastic are great as they allow fabricators to make all sorts of tremendous things. If as an engineer you machine an item out of a thermoplastic and it gets anywhere near its softening temperature during its life, it will stand a good chance of changing shape particularly if its under load. So for instance, if you machined a gear out of nylon and the environment got pretty hot, theres a chance those teeth may start to change shape. When it cools down though it’s no longer going to be that precision gear cut part you made not long ago. And the temperature doesn’t have to be that extreme, the main body of a gear is going to be fine but those little intricate teeth are going to struggle to absorb and dissipate the heat.
Items under heat radiation or close to a heat source that may get hot enough to cause a slight softening of the plastics are going to be an issue. So you need to opt for a thermoset type plastic in which the “heat forming” isn’t now going to be a factor. This is why there are still a lot of plastic gears that are made from Tufnol.
Who’s who and what’s what?
All the engineering plastics such as Nylon, Acetal, PTFE, HDPE, PEEK etc are all thermoplastics, as are the usual Acrylic, Polycarbonate and PVC etc, the only ones that are Thermosets are the Tufnol grades such as Whale, Kite and 1P/13 and all their other many grades that Tufnol make.
If you want your plastic to bend or form with heat and to stay in place, you simply need just about any plastic, Nylon, Acetal, PTFE etc will all form and re-form under heat, some are obviously better at it than others
But if you need it to stay where it is, once the temperature rises, it will have to be the Tufnol.