This is the third article in a series about plastics in conveyors.
In our previous two articles, we discussed how plastics can improve conveyors and explained why we chose plastic for our paddle material. In this article, we’ll discuss which plastics you should use, where you should use them, and why it matters.
Costs, Benefits, and Conveyor Materials
To begin, you must understand something about manufacturing. Manufacturers do their best to use the lowest-cost material that will achieve the desired results. We won’t use gold if tin will do. The same goes for our choice in plastics. We use a lower-grade plastic in the paddles, where you’ll need a certain amount of elasticity. But for the wear strips, we most often use UHMW, the proven material of choice for sliding steel.
UHMW, of course, has limits. It has challenging thermal properties. But we’ve dealt them by making the strips in short-enough pieces so the connections can absorb the expansion.
UHMW’s pressure rating is another limit to the plastic. The rating is fairly low. On straight sections, this isn’t a problem, as the chain weight is distributed over the entire length of the wear strips so that at any given point the pressure is well under the plastic’s limits. In the curves, however, UHMW isn’t adequate, as the pressures are too high. So, we use high-pressure nylon in these sections.
You may ask why, if high-pressure nylon does a better job at handling pressure, do we not use it for all the wear strips? The answer goes back to cost and benefit. High-pressure nylon costs much more than UHMW, and its advantages over UHMW are limited in the straight sections due to the low pressures involved. (If the conveyor is operating within its limits, why exceed what’s expected of it in terms of its design? Why add cost without benefit?)
We began the article by explaining that manufacturers want to use the lowest-cost materials that will achieve the desired result. It’s worth questioning what the result is. Manufacturers design conveyors with different results in mind:
- A conveyor that they can sell under a certain price point
- A conveyor that prioritizes certain features
- A conveyor that works well for a specific material
At Biomass Engineering & Equipment, we aim to produce high-value equipment that a) resists wear and lasts b) is energy efficient, and c) is easy to maintain. Over the life of the equipment, we believe producing high-quality equipment this will result in the most cost-effective choice for our customers. All our material choices, including plastics, work toward this end.