Living in the plastic age

摘要

THE EXPERTS AT LEE SPRING DRAW ATTENTION TO THE WHEN AND WHY OF PLASTIC SPRING. The when and why of plastic springs is rarely a simple matter, made as they are from highly engineered composites and technically advanced new generation materials. Typical properties include operation at elevated temperatures, neutral magnetic characteristics, light weight, low thermal conductivity, electrically insulating and ability to recycle at end of life. Lee Spring has worked very closely with Sabic Innovative Plastics to select the right material, adopting the Ultem resin, which is a very high-strength plastic, for compression springs ex-stock. Ultem polyetherimide performs in continuous use to 170°C and in the LeeP springs is designed to perform under load with minimum side thrust. This is achieved with a design that has a nearly rectangular cross section to maximise the amount of active material used as opposed to the more common round wire spring design. The exact cross section is a slight trapezoid to facilitate manufacturability. The design element that proved difficult yet critical is the configuration of the ends to provide for minimal side thrust and maximum flat load bearing surface without creating stress points or increasing the solid height while again accounting for manufacturability.