The deflection coiling process relies on the theory of elasticity and plasticity to produce helical springs of all shapes and forms. Deflection coiling produces a spring by introducing wire between two or more opposing feed rollers that drive the wire through precisely-sized wire guides until it reaches the coiling area. The opposing drive rolls, referred to as feed rolls, apply a controlled amount of compression force on the wire as it moves through the wire guides. As the wire is fed continuously under force, the tooling bends (deflects) the wire in a path which results in a continuous helical spring form.
The bending action includes enough plastic strain to exceed the yield strength of the wire material and permanently form it into the desired spring shape. These fundamental principles make it possible to form coils with outside diameters ranging from 0.150mm (.006 inches) to several feet or more in size. Wire diameters can range from wire as small as 0.020mm (.0008 inches) in diameter to 25.4mm (1 inch) in diameter or more. Wire feed speed typically ranges between 1,270mm (50 inches) per minute and 50,800mm (2,000 inches) per minute depending on the coiling material, desired spring configuration, and length.
There are two main types of deflection coiling which dictate the type of coil tooling and machine used to make a spring. These are single-point coiling and two-point coiling. Each type of coiling has specific characteristics which work well for certain spring-making applications.
Deflection coiling utilizing one coiling point tool.
Deflection coiling utilizing two coiling point tools.
A variety of metals and alloys are used by the industrial and medical device industries to produce coils.