Common Culprits Behind Coil Spring Breakage

Kilen identifies three common culprits for spring breakage and offers advice on how to combat these to ensure the longest possible service life.

As a key component in a vehicle’s suspension system, coil springs must handle high levels of stress as they support the vehicle’s weight whilst isolating it from the road. A spring’s lifespan comprises many millions of cycles, yet even the best made springs will eventually grow tired and start to sag. Vehicle ride height will decrease and may become uneven, affecting vehicle handling and braking distance. Breakage, however, is the main reason for spring replacement, and this can be caused by a number of factors.

Corrosion

Springs are constantly exposed to the elements, as well as to stones, grit and potholes, so they need to be made from high quality material, with their surface suitably protected from corrosion. Corrosion is the most common cause of spring failure, reducing the cross-section of the component and weakening it. Defects and chips in the layer of lacquer are unavoidable, and without additional protection, the spring steel will start to rust immediately, leading to creep corrosion beneath the lacquer, significantly speeding up the process towards breakage.

Manufacturers such as Sweden-based Kilen produce springs that are designed to withstand the ultimate test – the harshest conditions of a Scandinavian winter. Each spring is made from the highest quality specialist spring-steel, and protected from corrosion by zinc phosphate and epoxy powder paint, as required by the most demanding OEMs. Poor heat treatment Coiling a spring is only part of the job and effective heat treatment is also vital to produce a ductile and durable spring. The chances of premature spring failure increase if effective heat treatment isn’t applied to remove the negative internal stresses introduced during the coiling process. Heat treatment at the correct temperatures, and for the appropriate duration, is critical to reduce the risk of breakage during use.

Lower quality wire

Poor quality spring wire, often with surface and inner defects, significantly increases the likelihood of premature breakage. Even small surface fissures or occlusions within the material will lead to premature spring failure, and it is therefore vital to choose a supplier such as Kilen that only uses high grade specialist ‘spring’ steel from selected mills worldwide.