Plei-Tech® polyurethanes, based upon NDI, PPDI, and TDI are typically used as vibration absorbers and in shock absorbing applications. Depending upon the application requirements, these polyurethane compounds are varied in configuration, durometer and chemical make up to offer the best shock absorption performance.
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.
As a general rule, 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.