Double L Global, an Idaho-based potato equipment manufacturer, for instance, relies on a proprietary performance-based polyurethane formulation from Argonics called Kryptane for components used to clean and sort potatoes. This includes gentle rollers, rotating cleaning stars and rugged, load-bearing parts.

[Roy] Withers says Double L utilizes the proprietary urethane for a recently developed component designed to sweep product off a conveyor path. Previously, the component consisted of an integrated polyurethane paddle and a torsion spring. However, issues would often arise with the integrated paddle spring because the springs were inconsistently wound, causing the component to look aesthetically askew. The misalignment also often meant costly rework.

To create a more aesthetic and streamlined part, Withers inquired as to whether the performance requirements of the torsion spring could be achieved by making the entire part from polyurethane. In order to achieve the desired spring performance, Withers felt the two design variables he could use were the cross-sectional area of the part and the durometer of the urethane. Initially, Withers measured the metal spring’s spring rate in an attempt to match performance requirements. He then developed a design with a specifically calculated cross-section.

Argonics delivered four different polyurethane prototypes. Double L then physically tested the prototypes by seeing how much force it took to bend each and how far it would deflect. After a few iterations, the correct durometer and cross-section were identified, and the urethane part went into production. Now, there is no metal spring; it’s all one piece.