Ball plungers offer a reliable solution for indexing and positioning applications. By default, they remain in a closed position. When pressed against a part, however, ball plungers will retract. With their spring-loaded retraction mechanism, ball plungers can position and lock parts in place. Below is a breakdown of the parts in a typical ball plunger.
Ball
All ball plungers have a ball. That’s essentially what distinguishes them from other types of spring plungers. Located at the tip, the ball serves as the point of contact between a ball plunger and the part with which it’s used. The ball sits in a notch that allows it to retract within the ball plunger when pressure is applied.
Balls used in ball plungers are available in different materials, some of which include the following:
- Stainless steel
- Hardened steel
- Nylon
Body
The body is the main housing part of a ball plunger. Consisting of a cylindrical and hollow tube-like structure, it holds all of the other parts, including the ball.
Most ball plungers have a threaded body. There are helical ridges or “threads” on the exterior of the body. This threaded design allows ball plungers to fit into threaded holes. You just need to choose a ball plunger in the right size for the tapped or threaded hole.
Spring
Another important part of a ball plunger is the spring. Most ball plungers feature a small compression spring in the body. Its job is to apply constant pressure to the ball. The spring, of course, will compress and become shorter under an external load, such as that of a part. When this occurs, the ball will retract within the ball plunger.
The spring rate will determine the amount of pressure needed to retract the ball. A high spring rate will result in a stiffer spring, meaning more pressure will be needed to retract the ball.
Drive Type
Ball plungers have a drive type. The drive type is the mechanism by which a ball plunger is driven into holes or objects. It’s part of the plunger’s body. At one end of a ball plunger is the ball. At the other end is the drive type.
Most ball plungers have a slotted drive type. As the name suggests, this drive type consists of a slotted indentation that supports the use of a flathead screwdriver. You can install, as well as remove, ball plungers with a slotted drive type using a standard flathead screwdriver.