Unlike many spring shops who may specialize in certain kinds of springs (compression, extension, torsion), Tru-Form can make them all. When combined with our CNC Wire Forming machines, our 30 coilers and torsion machines allow us to deliver both small and large quantities. Compression springs are most common and are made in large quantities with automatic coilers that drive rollers working in pairs to force wire through guide tubes toward coiling points which in turn force the wire around a mandrel to form the coils. Our automatic coilers handle wire typically 0.010 to 0.5 in. in dia. For smaller-batch springmaking, we use semi-automatic machines which run slower than automatic but set up more quickly.
Following the coiling operation, the next step in spring manufacturing is flattening the ends, typically done on an automatic grinding machine. When making extension springs, we form loops or hooks on the ends of the springs. Similarly, the ends of torsion springs are also formed, via secondary operations. Other secondary operations include heattreating, as well as shot peening to relieve internal stresses and surface imperfections, which can more than double spring service life.
There are three basic principles in spring design: The heavier the wire the stronger the spring; the smaller the coil diameter the stronger the spring; and the more coils in the spring the less load needed to move the spring a certain distance.