How to specify indexing plungers, and their benefits

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Ensuring engineers are working with secure and safe components is vital for machine efficiency and worker safety. Indexing plungers are a commonly used component within machine building in order to secure moving components within a tight space; however, choosing the right plunger for each application is critical. Marcus Schneck, CEO at norelem, explains what to consider when choosing an indexing plunger and the benefits they bring.

How to specify indexing plungers, and their benefitsOver the past five years there have been 7,200 reported major accidents within the manufacturing industry, with 33,000 workers who have suffered from illness caused by working within the manufacturing field.

In manufacturing, manual handling of machinery is an everyday necessity. However, in the hope of doing things faster and more efficiently, safety is sometimes overlooked, leading to accidents and injuries.

These shortcuts might get things done more quickly but they also pose greater risks, which will only prove costly in the long run. This could be as small as not fitting a component properly or positioning within the machinery correctly, or even down to choosing the incorrect component for that application.

With component handling safety a major concern for the manufacturing industry, indexing plungers were created to improve the robustness of moving parts, to prevent components slipping out of place and posing potential risk.

For example, indexing plungers – used to lock or index machine elements – can be used in machine construction to secure rotating or linear sliding parts. Operated by a pulling knob or a pull ring, a mechanism in the plunger withdraws an indexing pin from a hole in a counterpart enabling connecting machine elements to be quickly and easily locked or released.

Indexing plungers provide speed and efficiency within machinery that will ensure safety and security whilst components are in operation. Therefore, using indexing plungers can save maintenance and repair costs further down the line.

Choosing the correct indexing plunger is key to avoiding injuries and accidents within manufacturing environments. The use of indexing plungers allows the quick adjustment of movable machine components, often with a pre-determined stop mechanism to assist when machine parts are in motion.

Plunging into the unknown

There are a large variety of indexing plungers available on the current market, all with different benefits:

  • Indexing plungers with thread lock: the thread lock allows the plunger to be screwed into the exact depth required, and no spacer ring is required.
  • Indexing plungers with extended indexing pin: extended locking pins are used when larger distances between locking pin and workpiece or counterpart must be bridged, essentially closing that hazardous gap.
  • Indexing plungers with cylindrical pin and indexing plungers with tapered pin: the precise design of both of these indexing plungers guarantees high repeating accuracy when assembling two elements.

The tapered shape of the indexing pin/the indexing bore makes the positioning virtually clearance-free and therefore highly precise. For high-precision indexing plungers, it is recommended using special mounting sockets to take up the locking pin.

Mainly developed to resolve positioning issues of moveable components, indexing plungers are also useful for precise applications, especially within tight spaces or thin walls, thanks to their compact design.

It is critical that engineers pick the right indexing plunger for the application. If not, these components, which are designed for speed and efficiency in positioning and locking, will in turn to do the opposite, slowing down production causing lost time.

Safety first

Indexing plungers also perform a crucial safety function. Any unplanned movement of components could cause a number of issues which could lead to unsafe working environments for your employees as well as potential damage to your machinery. A secure machine makes for a secure environment and fewer costs to be paid further down the line.

Indexing plungers provide that extra security by ensuring loose and moving components are fixed into place to avoid any slips, scrapes or jamming of machines. Securing these components will also reduce the chances of workplace accidents from workers manually handling machinery.

Best practice is to make sure you use the most reliable and safest products on the market, fit for the specific application. If the wrong locking bolts are used, for example, the counterparts cannot be fixed and positioned correctly. This in turn has an impact on quality and safety within the workplace.

For engineers looking for automatic engagement of the pin, an indexing plunger with a lead-in bevel is the optimum choice. This type of plunger is subjected to a unilateral force, providing automatic engagement due to the plunger pin snapping in securely by the spring’s force and stops any further movement of attached components.

For added safety, to release the lead-in bevel it requires a manual action of pulling on the mushroom knob which will then retract the pin.

Comfort and ergonomics are also key to safety and workers’ long-term health. When working with machinery, workers must have access to comfortable and easy-to-use components with friction-free functionality. Each machine operator will have different needs, so ensuring you have indexing plungers that are universally operable is essential.

Whether it’s the material of the component or the structure and functionality, providing ergonomic solutions will prevent injuries for the worker, as this will reduce the chances of strain whilst handling components and machinery.

Knowing your options with the range of standard components available is essential to selecting the right product for the application. There are numerous indexing plungers from norelem which are all designed to secure machine components in different ways. Security and safety should be at the top of your list when it comes to priorities.

After all, a healthy worker is a happy worker. Using indexing plungers where moving components are present will not only give you peace of mind but will also ensure higher efficiencies and productivity.

For more information on norelem’s range of indexing plungers, go to

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