The Basics of Spring Plungers

Spring loaded devices, also called spring plungers, provide an easy way to install springs in a piece of equipment. However, even experienced technicians sometimes don’t fully appreciate the advantages and limitations of this piece of hardware. Here are some tips on selection and installation.

What Are Spring Plungers?

Installing bare springs into tooling components can be tedious and frustrating. The spring must be compressed for insertion and these forces can damage the spring if the technician is not careful. During placement, springs can get away from the installer, flying out of the device and ending up who knows where. Finally, there are some configurations which are simply impossible to get a spring into.

Spring loaded devices protect the spring within a cylindrical body that holds it in place. A plunger extends from the tip of the plunger to allow activation of the spring inside. Because the spring is held firmly in place, there is no danger of it escaping. During installation, tool forces are directed at the plunger body rather than the spring, reducing the chance of spring damage.

Some spring loaded devices have a locking element, typically made of nylon, to hold the plunger body in place. This regulates the position and therefore the force of the spring. The end force in spring plungers is more precise than that of bare springs. Using them in industrial products allows more efficient operation and greater safety because the spring force is predictable.

Materials Used In Spring Plungers

There are a number of materials used in the manufacture of spring loaded devices. The selection of body and plunger materials is based on the benefits and limitations of each option.

Like many industrial products, steel is a popular choice. It is strong and durable, providing protection against wear and stress. It is an inexpensive choice ideal for most solutions. Typically manufacturers use carbon steel, often case-hardened to provide extra wear resistance. Spring plungers that will be exposed to moisture, corrosive environments or high temperatures are typically made of stainless steel which is more expensive but provides better resistance in these conditions.

The hardness of steel can be a drawback. Softer metals, such as brass or aluminum, may be damaged by coming into contact with steel parts. Minor damage can be aesthetically unappealing while more serious damage can lead to the failure of the soft metal parts and catastrophic damage to the machine.

For these applications, manufacturers use spring loaded devices made of artificial materials such as nylon, Delrin (polyoxymethylene) or phenolic resin. These materials provide high strength and durability but are elastic enough not to scratch softer metals.

Installation Tips

Although spring plungers can be installed with screwdrivers or hex key wrenches, most experts recommend using dedicated spring plunger wrenches particularly if inexperienced with spring plungers. Using the wrong tool runs the risk of over-compressing the spring and damaging it. As any technician knows, you should always use the right tool for the job.

The biggest danger when installing spring plungers is using too much torque. Although they resemble bolts or screws, their bodies are hollow and they can tolerate only a fraction of the force a solid body can. Technicians who exert as much force on plungers as they do on screws end up with a lot of broken plungers. If in doubt, check with the manufacturer for maximum installation torque.

If the plunger includes a locking element, the element is designed to compress against the threads of the tapped hole to provide the locking force. While this is fine in steel or other hard metals, softer metals may deform under the pressure. Try using a plunger without a locking element. If your application needs the locking element, drill tap holes slightly larger than the spring plungers being used. There will still be enough force to engage the locking element but not enough to damage the metal. If this still doesn’t serve your needs, contact the manufacturer to see if other materials can be used in the locking element that won’t deform the tooling components.

A spring plunger is a specialized piece of hardware which provides a function unlike anything else, but which must be fully understood to be installed and used effectively. Treat it like the unique item it is and you will have more success using them in your equipment.


Post time: 02-12-2017