How to Choose Indexing Plungers

Indexing plunger by Monroe

Indexing plungers are commonly used to position and lock parts in place. They are detent devices that, as the name suggests, are designed for use in indexing bores.

Most indexing plungers feature a spring-loaded pin. When you engage an indexing plunger — typically by turning a knob or pulling lever — the pin will retract. The indexing plunger will then move freely. Releasing the indexing plunger, on the other hand, will return the spring-loaded pin back to locked position. While most indexing plungers use this same design or a variation thereof, they are available in different types.

Flange vs Non-Flange

Some indexing plungers feature a flange. The flange consists of a protruding piece of material around the body. You can use them for same positioning and locking applications as other indexing plungers.

Other indexing plungers don’t feature a flange. Instead, they consist of entirely of a body, which is typically affixed with a knob or lever at the top.


You should consider the supported position when choosing indexing plungers. Some indexing plungers are designed for use with indexing applications that require a fixed position. Other indexing plungers are designed for use with indexing applications that require a retracted position.

Lever vs Knob

As previously mentioned, most indexing plungers feature either a lever or knob. You’ll need to pull the lever or turn the knob to lock to retract the spring-loaded pin.

Both lever- and knob-style indexing plungers work in the same way; they simply use different methods to release the spring-loaded pin. Nonetheless, you should consider the style when choosing indexing plungers. Some people prefer lever-style indexing plungers, whereas others prefer knob-style indexing plungers.


Indexing plungers are available in different materials. Some of the most popular materials in which they are made include stainless steel and carbon steel.

Stainless steel and carbon steel are both iron alloys, but they are comprised of different compounds. Stainless steel is an iron alloy with 11% or more chromium content. Carbon steel, conversely, is an iron alloy with a high concentration of carbon content. Indexing plungers made of stainless steel offer excellent resistance to rust and corrosion. Indexing plungers made of carbon steel, though, are stronger and more durable than those made of stainless steel.


In addition to stainless steel and carbon steel, many indexing plungers feature a finish. The body, for instance, may be plated in zinc alloy, and the plunger may feature an oxidized steel finish.

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