ForceCheck Force Gauges

Chuck-Collet Force Application Worksheet

Hydraulic Collet Holder Force Worksheet

Download PDF for worksheet.

Workholding Collet Force

Information on operating principle, accuracy/repeatability, and use cases.

Understanding Chuck Forces

The “Total Gripping Force” (F_total) is defined as the arithmetic sum of the individual radial forces exerted by each jaw.

 

The force value shown on the ForceCheck display represents the measured radial force of a single jaw (F_jaw) at the measurement diameter. This is different than the total gripping force of the chuck.

 

Calculating Total Gripping Force

 

Since the jaws move simultaneously and are driven by the same mechanism (usually a scroll plate or a hydraulic wedge), under ideal conditions the force is distributed equally among them.

 

F_total = n × F_jaw

 

Where:

• F_total = Total gripping force
• n = Number of jaws
• F_jaw = Force measured at a single jaw (value shown on ForceCheck display)

Examples:

3-jaw chuck

• Displayed Force Fjaw = 10 kN
• Total Gripping Force F_total = 3 × 10 kN = 30 kN

5-jaw chuck

• Displayed force = 10 kN
• Total gripping force = 5 × 10 kN = 50 kN

Important Distinction: Force vs. Pressure

It is a common point of confusion whether the forces “cancel out” since they are opposing each other.

• Net Force on the Part: The vector sum of forces acting on a properly centered part is 0 kN. This is why the part remains stationary in the chuck.
• Gripping/Clamping Force: In terms of holding power and part deformation, we use the sum of the magnitudes. This total force determines how much friction is generated to resist cutting forces and how much the part might “crush” or distort.

Factors That May Change This Value

Your “real world” force may differ based on these conditions:

• Dynamic Loss (Centrifugal Force): If the chuck is spinning, the jaws want to fly outward due to centrifugal force. This reduces the actual gripping force. At high RPMs, the force when compared to a static condition could drop significantly.
• Friction and Lubrication: If you are measuring the force at the sensor but the other jaws are poorly lubricated, they may not actually be producing the same force.
• Part Geometry: If the part is not perfectly round or the jaws are not making full contact, the force distribution might become uneven, though the total input force from the chuck mechanism remains the same.