A variety of materials are used by the industrial and medical device industry to produce coils and springs. The most common of those materials are listed in the following table along with their relative tensile strengths. Very soft materials such as gold, silver, and copper which have very little tensile strength are not good deflection coiling materials because they have difficulty withstanding the forces required to form the coil. The most popular wire materials for small medical coils are 304V Stainless Steel and Platinum Tungsten. Typically, the wire for small coiling applications is diamond drawn to very precise tolerances. Sometimes the wire can be rolled to final size for special shape applications such as with flat wire. Each material has particular traits which need to be addressed when tooling is selected. Our special KineCoil coiling point tooling overcomes the challenges of coiling stainless steel wire encountered with standard carbide coiling points.
The quality of the incoming wire material is critical to the coiling process. The wire should have a minimum amount of cast (for round wire) and camber (for flat wire) and should lay as flat as possible on a flat surface. Any residual stresses in the wire can affect the behavior of the coiling process. Residual stresses can cause variations in coil diameter, pitch spacing, and stiffness. The spooling of the wire is also very important. The wire must not be overlapped or wound too tightly on the spool .
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.