The choice to hot coil or cold coil is predominantly determined by the size of the wire needing to be coiled and within Lesjöfors Heavy Springs, our experts in Finland are the masters of the hot coiling process.
Large springs, using a wide wire diameter commonly seen across our oil and gas, mining and rail customers require a hot winding process as the extreme heat allows up to 65mm wire diameters to be coiled.
The process of heating up wire to approximately 900 degrees celsius, quenching in oil and tempered to complete the heat treatment, allows the spring material to be coiled to the specifications required - more often than not for extreme environments for heavy industry applications.
There are two processes for cold coiling. Commonly, wire that has already been heat-treated is cold coiled as its material is already at peak strength and this allows for numerous spring and wire forms and functions, commonly manufactured by many. However, this restricts the availability of large wire diameters and small indexes.
Our expertise, is coiling wire in a soft state and then heat-treating it to its final strength after coiling, which enables larger wire diameters and smaller indexes – a core focus for our automotive, agriculture, motorsport and power generation customers.
Your spring, your choice and our experts across Heavy Springs are on hand to advise the best material, design and manufacture for the lifetime and purpose of your spring.