Whenever lead wires or cables are subjected to motion after installation, flexible wires should be specified.
Flexible wires require both:
- Flexible Conductors
Stranding: Flexible conductors start with many strands of wire "bunched" together to make the desired conductor size. In the North American market the American Wire Gage (AWG) system is used. The rest of the world uses the metric system with conductors sized in millimeter squared. For more conductor size information get our Wire Card.
Flex Life: The next consideration should be given to the flex life of the wire. When a large number of flexes are needed, high strength copper alloys should be considered.
Plating: Plating on the conductors can be Tin for -20C to +150C. Tin is often specified to enhance the solderability when terminating the wires. Silver plating can be used for -60C to 250C. For temperatures above 250 C, nickel plating is used.
The insulation material is chosen by the environment and voltage rating needed.
Silicone: For the limpest or most flexible material, silicone rubber is the material of choice. Silicone rubber has poor abrasion resistance and outgases in a vacuum or space environment. It can be post baked to reduce the out-gassing. Routing can be changed to keep the silicone rubber from being abraded during flexing.
PVC: Flexible PVC can be used when allowed. PVC contains a plasticizer that can slowly leave the wire resulting in stiffer wire over time.
TPE: TPE materials are often used for medical lead wires and when autoclaving is required.
FEP: For the smallest constructions, FEP (Teflon®) is used. FEP in flexing applications is applied with a smaller wall thickness, which is more flexible than normal FEP insulated conductors.
The combination of the right conductor and insulation will insure that your wire will perform as desired.