How to Use a Spring Ball Plunger

Carr Lane Mfg. is an industry-leading provider of force ball plungers and many other vital manufacturing products. Since our beginnings in 1952, Carr Lane Mfg. has provided innovative engineering products and solutions for a variety of industries.

All products are proudly made in the United States or EU.

 

What is a Spring Ball Plunger?

A spring ball plunger is a spring-loaded device used to position a workpiece. Inside of this plunger is a small ball and spring, which rises and sinks depending on the amount of applied pressure on the plunger. After pressure is reduced, the ball will then rise back to the top of the spring. The ball is not capable of sinking too far, making it ideal for smaller loads.

 

Uses of A Spring Ball Plunger

A spring ball plunger is used in many different applications, everything from at-home hobbies to large manufacturing facilities. It’s common to see these spring-loaded plungers used in detent and rolling applications.

This spring-loaded device is most suitable for smaller weight loads. When supporting heavier loads, the ball will sink too deep into the workpiece.

 

How to Install a Ball Plunger

Ball spring plungers are easy to install. To install the ball plunger, drill a hole deep enough for the spring-loaded device to fit into. Leave enough space for the top of the ball to protrude out of the board. This allows it to easily perform the locking technique.

For Carr Lane Mfg. ball plungers, we recommend creating a hole 0.8mm larger than the major thread’s diameter. This allows the ball and spring mechanism enough space to properly extend and collapse.

 

Carr Lane Mfg.’s Selection of Ball Plungers

We have a wide selection of ball plungers available. Currently, we offer plungers made from these materials:

  • Steel
  • Stainless Steel
  • Stainless Steel with Delrin Ball
  • Delrin
  • Delrin with Delrin Ball

 

Spring Ball Plunger

Calculating the Breakaway Force of Ball Plungers

To calculate the side force needed to slide a ball plunger out of its detent hole, refer to the free-body force diagram to the left. In the diagram:

  • S = Side force
  • F = End force (spring force)
  • R = Reaction force
  • A = Countersink angle
  • The reaction force (R) is perpendicular to the contact surface.

Solving for side force (S):

Spring Ball Plunger

End force (F) depends on how far the spring will be compressed, which depends on how far away from the sliding surface the ball plunger is installed. Maximum spring compression and end force occur as the ball breaks out of its hole.

 

Examples of Breakaway-Force

A CL-40-BP-3 ball plunger (1/4-20) exerts an initial force of 18 N, a half-way force of 35.5 N, and a final force of 53 N. With a 90° countersink angle and half-way compression:

Spring Ball Plunger

 

Installing Ball Plungers

To obtain full locking torque, countersink the installation hole to avoid cutting the locking element. Countersink at a 90° angle to a diameter .8mm larger than the major thread diameter. Then, as you screw the plunger into its hole, the locking element will be compressed, not cut.