Cobra Springs are designed and manufactured to demanding standards using high quality micro-alloy spring steel. They are hot wound on state of the art coiling machines, oil hardened, electronically tempered, shotpeened, scragged and loadtested for maximum reliability.
We use the following steps to produce our high performance springs, which are all hand made locally in christchurch for optimum quality and finishing.
Spring steel wire is heated to nearly 1000ºC before being hotwound. Hot winding reduces stress in the steel during coiling as opposed to cold winding.
The springs are hardened in a special oil quenching bath then they are transferred to an electronic furnance. A precise hardness setting is required to prevent the spring from cracking or sagging when in use.
The spring is shotpeened to relieve surface stress. Thousands of tiny steel balls are fired at the springs to relieve the stresses built up during winding and tempering.
The spring is then scragged or 'preset'. The procedure twists the steel to its limits - never again will it be twisted to this extent. Upon completion the height of the spring is set.
The final process, powder coating, gives a high quality protective coating to the spring.