Sometimes clients are surprised when they request UHMW lining for a solution (such as a hopper liner) and, after questioning the application, we suggest for them to select urethane instead. This sometimes comes as a shock and we are forced to explain ourselves. In order to save ourselves some future awkward situations we want to discuss the differences between the two types of liner.
UHMW – Very likely the best known engineering-grade thermoplastic, Ultra High Molecular Weight Polyethylene (UHMW-PE) has developed a very positive reputation. While “UH” is indeed a great balance of cost, versatility and low co-effecient of friction (important for a liner!) it does have its weaknesses. Impingement, which is material hitting on an angle, could be called the “Achilles Heel” of UHMW.
In applications where abrasive material impinges, even material made of small particles, such as grain, UHMW is not a good option and will quickly wear or chip. This is in contrast to its great strength in non-impinging wear guide applications. People often do not know UHMW will be strong in one situation but weak in the other. The height the abrasive material falls onto the liner only makes the situation more acute.
Polyurethane – While not as slick as UHMW, Polyurethane does have outstanding impingement resistance – especially the mid-grade durometers such as Redco™ 430. This resistance alone in some applications is well worth the trade-off in coefficient of friction. That is not to say polyurethane’s coefficient of friction is bad – its not and obviously could not function as a liner if material stuck.
A general rule of thumb is that as the urethane becomes harder the lower the coefficient of friction becomes. In fact, we manufacture a black lubricated bearing-grade urethane (750SXL) which is very slick and can run for long dry periods without lubrication. Not saying it makes a good lining material – but we are trying to change your perception of polyurethane.
The best thing you can do is approach your Redwood rep with the application and trust their recommendations. We do care about the selection of the right material and we will get second opinions from other experienced co-workers to ensure the best material is chosen. That does require you as the client to keep an open mind, which is perhaps the best way you can help us to help you.
For assistance with your lining needs please contact us today:
CDN: 1 800 667 0999
USA: 1 866 733 2684