Plei-Tech® custom molded polyurethanes are frequently used in demanding applications where shock absorption, vibration dampening, and noise reduction are required. Common urethanes that do not exhibit excellent dynamic performance, low compression set, and high cut and tear resistance will quickly fail in these vibration damping applications.
Pleiger Plastics can design, mold, and test shock absorbing polyurethane bumpers to develop stress/strain (compression/deflection) curves required for bump stops, damping bumpers, and bumper systems to your specifications. Shock absorbing applications are both common and highly variable, since they can include prosthetics, coal car draft gears, and pump check valve balls. Equipment bumpers can be designed for shock absorption on loads from 1 to 200,000 pounds. The Jobel impact bar is a specially designed impact system for use on conveyor belts to increase belt-life at transition points.
Plei-Tech®15 Foam is a material used for bumpers where low load and high frequency occurs. This molded foam material can be compressed as much as 70% with little permanent compression set. (Compression & Deflection curves)
Foam products will exhibit linear spring curves over a longer distance than solid elastomers, before becoming asymptotic. The spring characteristics can be varied with the foam density.
Polyurethanes under the Plei-Tech® name are based upon PPDI, NDI, and TDI and are typically used in shock absorbing applications or vibration absorbers. Depending upon your requirements, our polyurethanes can be varied in durometer, configuration, and chemical make-up to offer the best shock absorption performance.
As a general rule, solid elastomer compression elements should not be compressed more than 25% of the original height. As the frequency of compression increases, the percentage of compression should decrease in order to maximize bumper life.
Shape factor and durometer are the two criteria that most effect spring rates of elastomers. By varying durometer and shape factor, a wide range of spring curves can be achieved. Shape factor is defined as area in compression divided by area free to bulge.
In compression it is import to note that unlike foam, solid elastomers have a very short linear spring curve before the spring rate dramatically increases. Similarly spring rates relative to shore A change significantly after 85A and are more linear realative to shore D.
For more information on Pleiger Plastics’ polyurethane bumpers, please contact us today.