Collet Force Operating Principle

We often get questions on the operating principle of the sensors. First a bit of explanation on what is really happening with a collet – a collet generates a force over a cylindrical area, which is ultimately a pressure. In practice, that pressure often varies at different locations along the axis of the collet. For example, with a 5C or collet that is segmented at the front and solid in the back, the pressure will be considerably higher to the front.

In measuring force, our sensor measures at a single axis perpendicular to the axis of the collet. What is displayed is a "vector force" on that axis in Newtons or Pounds-Force. This is a snapshot of the whole collet that simplifies what is really happening but it provides a quick reference that will allow a user to compare different setups, machines, etc.

Because of the way we’re measuring, the number displayed by the sensor generally can’t be directly correlated to the pressure gauge "on the back of the machine" due to the long chain of hydraulic/pneumatic/mechanical links between them.

Collet Force Accuracy/Repeatability

Several factors influence repeatability: friction in the system, mechanical advantage of the closer mechanism, inconsistencies between clamping cycles, collet diameter tolerances, sensor insertion orientation, etc. Because of the large number of variables, a user shouldn’t expect highly consistent repeatability. Generally we see something in the +/-10% but it can sometimes be significantly higher as the variables mentioned can fluctuate between clamping cycles.

We recommend considering the collet force gauge as a comparison tool. For example, comparing the collet force between two machines with automatic systems. Another example would be variance in holding force between operators on a manual collet closer. Less important is the actual number measured; more important is a comparison between the numbers. Variance can be expected due to the multitude of variables at play: +/-10% is likely ok whereas 2x the force would be significant.

Common Use Cases for Collet Force Gauges

• Monitoring for changes in force over time: Changes can indicate mechanical problems, need for lubrication, etc.
• Comparison between machines: To ensure consistent production, multiple machines running the same part can be adjusted to approximately the same force.
• Job setup: Establish a "known good" holding force for running a specific job that can be easily re- set up next time the job is run.
• Establish force for delicate parts: Holding force for thin-wall or other sensitive parts can be a balancing act between having sufficient holding force and distorting parts. The collet force gauge can help to establish an optimum force.

Contact us with questions

Please contact our Applications Engineering Team at 815 962-5600 with questions on your collet system. We are happy to assist in determining if our collet force gauges will help for your specific workholding challenges.

ForceCheck Workholding Collet Force Gauge

ForceCheck collet force gauges provide a quick and easy way to check force on collet workholding systems.

Applications for ForceCheck workholding collet force gauges include:

-Comparison of holding force between machines, allowing for consistent and repeatable production results regardless of mechanism (manual, hydraulic, or pneumatic)
-Periodic verification to assess if preventive maintenance is needed
-Establish correct holding force for running a particular part or job
-Determine optimal holding force for thin-wall, rings, and other parts sensitive to damage or distortion when machining


A sensor is needed for each diameter to be measured. A ForceCheck base set with display is needed to display results (order separately).
Sensors are also available in low-force versions. Contact us for further information.