NHK Spring Co Ltd developed a suspension spring using CFRP (carbon fiber reinforced plastic) for passenger cars.
Compared with suspension springs made by using commonly-used spring steels, the weight of the CFRP-based spring is about 70% lighter. The company plans to sell it to automakers, aiming to start volume production of the spring in 2020.
In general, the weight of spring is cut by using hollow materials. This method enables to cut weight by about 20%. In recent years, GFRP (glass fiber reinforced plastic)-based springs are being developed, but only a few European manufacturers started to mass-produce them.
"It can be the world's first CFRP-based suspension spring," NHK Spring said.
For volume production, NHK Spring will procure carbon fiber materials from material manufacturers, mix them with plastic and form springs. Because of the difference in material rigidity between spring steel and CFRP, the number of turns of spring is reduced by about 30%. However, the diameter of spring wire increases by about 60%. As a result, the amount of materials used increases.
The challenge in volume production is the cost reduction of carbon fibers. The price of the CFRP-based suspension spring is expected to be several times higher than that of existing products.
"We will start volume production as soon as possible and cut costs through the volume production," NHK Spring said.
The company exhibited the new spring at Automotive Engineering Exposition 2017, which took place from May 24 to 26, 2017, in Yokohama, Japan.