Collets and Collet Bodies
Collets directly hold the tungsten in place when you tighten the back cap and create the electrical contact necessary for good current transfer. They are generally made of standard grade copper or tellurium copper.
Collet bodies screw into the TIG torch and accommodate various size tungsten and their respective collets, each of which range in size from .020 to 1/4 inches. They are also made of standard grade copper or tellurium copper.
When choosing collets and collet bodies, you need to consider two main factors.
First is price. Standard grade copper collets and collet bodies are less expensive, but they also tend to be less durable. Less expensive collet and collet bodies are also prone to failure under high temperature applications. After extended use, they do not secure the tungsten as reliably.
Conversely, the more expensive tellurium copper collets and collet bodies have better heat resistance on higher amperage applications. These consumables generally resist twisting or elongating and hold the tungsten more securely after extended periods of use. They also have more tensile strength and less ductility.
You also need to decide between a single- or two-piece system (See figure 1). Typically, manufacturers sell collets and collet bodies separately to match a specific tungsten size. For example, you would purchase a 1/16-inch Collet And Collet Body
to match a 1/16-inch tungsten. This system works well and accommodates a wide range of tungsten sizes, especially smaller ones.
Fig. 1 Choosing between a standard two-piece system (top) or a single-piece system (bottom) is one of the factors in determining which collets and collet bodies are best for you.
There are also single piece systems that combine the collet and collet body together. From a performance standpoint, they provide better securing force and are easier to remove when used in a demanding application. The reason for this factor is because the collet mechanism is further away from the heat and less susceptible to heat distortion. They also reduce the possibility of mismatching collet and collet body sizes, allow for quicker tungsten changeover and help simplify parts management.