Because plastic springs have the advantage that steel springs are difficult to replace, the United States, Britain, Japan and other countries are racing to develop and have achieved many research results, and some have been put into practical applications. Its development has generally gone through three stages.
Before 1970, it was the exploration stage of principle experiments. At this stage, there are more published applied theory analysis articles and phased research reports. During this period, because the thermosetting plastics suitable for engineering applications are still in the early stage of development, the development of engineering plastic springs encountered many problems, such as poor temperature resistance, low hardness and wear resistance, high prices, and difficulty in making a wide range of Coil springs, coupled with design procedures, processing equipment, and process parameters have encountered some new problems to be solved, thus delaying the progress of plastic springs to practical applications.
Before 1980, it was the stage of practical development. At this stage, due to the development of the plastics industry, fiber-reinforced plastics (FRP=Fiberglass Rein-forced Plastics) that are temperature-resistant, wear-resistant and reasonably priced have been successfully developed, coupled with the development of automobile design in the direction of miniaturization and light weight, especially for petroleum Since the crisis, in order to reduce the weight of auto parts and save fuel, auto manufacturers have actively developed plastic leaf springs, which has promoted the development of plastic springs to practical applications. The outstanding development result at this stage is the practical application of FRP leaf springs in the United States.