Whether designing a disposable medical device, mass-producing a consumer charging cable or developing a wire harness for a piece of capital equipment, careful detail must be paid to connect the different components. This coming-together is most typically accomplished using some version of wire. Unbeknownst to the majority of the general public, this much design and engineering that goes into each of these types of wire. At the core of a wire are conductors aiding the movement of the electrical charge, the question is—how do we prevent the loss of the free-flowing electricity? Like a home keeping warm air in and cool air out in the winter, this is where wire insulation enters the picture.
Before we discuss what the “Insulation” is, let establish the very basic anatomy of a wire. Within a “simple” wire you have, moving from inside to outside;
What is “Insulation”?
Insulation provides resistivity to the wire, separating the conductors both electrically and physically. The insulation minimizes free flowing electric charges from the conductor segments of the wire. When choosing an insulation considering the environment it will be used in is crucial. Physical considerations can be things like temperature rating, flexibility, the life of the application, flammability and more.
What is the insulation made of?
Guarding against interference as well as keeping the signal as strong as possible, insulation always consists of non-metallic, non-conductive material to resist the flow of electricity. Insulators come in multiple forms; solids, liquids, and gases. For this discussion, we are only going to consider three types of solid insulators, those being: Plastics, Teflon, Rubber and Paper.
Plastic insulators range from various polyvinylchloride (PVC) to polyurethane and polyethylene—to name only a few of the more common. Pricing ranges from inexpensive PVCs to expensive implantable polyurethanes. Plastics provide use in diverse applications and exposures. Plastics have a vast range of rigidity and thickness.
Fluoropolymers are excellent insulators for high-temperature applications, they also have superior mechanical strength at high temperatures. The unique material that is Teflon provides unsurpassed electrical properties, such as, high dielectric strength, low dielectric loss and low dielectric constant.
Chosen for its long life, flexibility and performance under high temperatures, rubber is another common insulation type. Common rubbers include ethylene propylene, silicone and neoprene.
Originally used for its pure cellulose, for decades you could find paper in telephone cables—it’s true, kids, our telephones were once tethered to a wall by wires and cords and didn’t send pictures. Paper as an insulator has several drawing backs and has widely been replaced by plastics, rubbers and Teflon.
Now that you’ve crammed your head with knowledge about conductors and insulation and your dreams will be filled with wire, we can’t stop now. The next installment of Electric Wire 101 will be the exciting world of shielding. I know you can hardly contain your excitement—neither can we—so check back soon, or subscribe to our blog, for the long and short of shielding.
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