What Is a Ball Plunger?

Monroe Engineering ball plunger

Plungers are commonly used to position workpieces. Also known as a Spring-Loaded Device (SLD), they consist of a spring within a threaded body. While all plungers share this design, there are several different types, one of which is a ball plunger.

Overview of Ball Plungers

A ball plunger is a type of SLD that’s characterized by the use of a ball at the top. When pressure is applied, the ball sinks, thus compressing the enclosed spring. When pressure is removed, the compressive forces of the spring push the ball back up to its original position.

All ball plungers have a ball. The ball has a shallow depth, meaning it’s not capable of sinking very far. This shallow depth, however, allows ball plungers to easily change position under pressure. They will quickly sink under light loads, and they will quickly return to their original position when the load is removed.

The Different Parts of a Ball Plunger

Ball plungers contain a few basic parts. At the top is a small ball, which is typically made of steel. The ball is designed to sink when exposed to pressure. Pressure can be applied to the top of the ball or to the side of the ball. Regardless, the ball when will sink when exposed to pressure.

Below the ball is a spring enclosed in a threaded body. The threaded body contains grooves on the outside that guide the ball plunger during installation. Ball plungers have external threading similar to that of a bolt or screw. It follows the internal threading of a workpiece’s pilot hole so that the ball plungers can be installed. At the bottom of a ball plunger is a slotted drive. The slotted drive, of course, is used for installation and removal purposes. A driver bit grips the sides of the slotted drive so that the ball plunger can be driven into or out of a workpiece.

Ball Plungers vs Spring Plungers: What’s the Difference?

Another common type of SLD is a spring plunger. Technically speaking, a ball plunger is a type of spring plunger. The difference is that spring plungers don’t feature a ball at the top. Instead, they have a plunger- or pin-styled nose. Spring plungers still contain a spring within a threaded body, and they still contain a slotted drive at the bottom. Rather than a ball at the top, spring plungers have a narrow pin or plunger.

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