These terms are used interchangeably and sometimes together as "coil spring". In either case, a coil or spring is an elastic object that stores mechanical energy for functional use in a variety of mechanical applications.
The deflection coiling process came into popular industrial use in the early 1900’s to create extension springs, compression springs, and torsion springs. Deflection coiling is a metal forming process by which round or shaped wire is formed into helical spring shapes at high rates of speed. Coils produced by deflection coiling come in all shapes and sizes. However, the fundamentals of the process remain the same whether you are producing a coil with 0.001" wire diameter or 1" wire diameter. And, unlike coil winding, deflection coiling makes it possible to have multiple or varying outside diameters within a single coil which is also cut to length. Variable diameters can have many purposes including tapered lead-ins for insertion or guiding applications, or changing the stiffness in one particular area of the coil.
The deflection coiling process relies on the theory of elasticity and plasticity to produce helical springs of all shapes and forms.
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.