Read through a list of common workholding definitions to expand your knowledge of workholding manufacturing terminology. Select the first letter of the word from the list above to jump to appropriate section of the glossary. 



The accuracy of a chuck/expanding arbor measured in inches TIR is comprised of two components:

  • The distance between the centerline of the machine spindle and the centerline of the workholding device.
  • A random variation about the centerline of the workholding device caused by conditions built into the chuck such as internal friction and sliding fits. See repeatability.


A device that clamps the chuck or expanding arbor through the aid of pneumatic or hydraulic energy. arbor See definition of expanding arbor.


See definition of expanding arbor.



See definition of the workshop.



A workholding device which grips primarily on the outside diameter of a rotational part.

Clamping cylinder

See actuator.


A split sleeve which when expanded or contracted, grips the workpiece.

Collet chuck

A workholding device using a collet.

Compensating chuck

A chuck in which jaw(s) move to or away from the workpiece without altering the position of the workpiece.

Crankshaft chuck

A chuck capable of gripping and positioning a crankshaft off-center for turning or grinding operations.


Dead length

The action of gripping a workpiece without changing its axial position.

Diaphragm chuck

A chuck that uses the deformation of a flexible material to grip a workpiece.


Expanding arbor

A workholding device which grips on an inside diameter or feature.


Face driver

A chuck A split sleeve which when expanded or contracted, grips the workpiece.


Full indicator reading. Used interchangeably with TIR. TIR is generally preferred.

First operation chuck/expanding arbor

A device used to locate or support material, workpiece(s), or tool(s) during machining operations. Usually custom designed to hold a specific workpiece.


Indicating band

A diameter on the chuck body designated for measuring runout of a chuck.



A cylindrical or symmetric shaft, sometimes tapered, that locates on the internal diameter (ID) or feature of the workpiece.

Master jaw

The moving part in a chuck to which the top jaw is mounted. top jaw



A chuck/expanding arbor is said to have "pull-back" action if it simultaneously grips and pulls the piece part back against a workstop.



The random component of chuck accuracy measured in inches TIR.

Retracting jaw chuck

A chuck which grips shafts for turning the complete length by retracting jaws into the chuck face to allow the area previously gripped to be machined. Either a face driver or expanding arbor provides the torque when machining the area previously gripped by chuck jaws.

Rotational part

A piece part symmetrical about a central axis.


Second operation chuck/expanding arbor

A workholding device designed to grip on previously machined surfaces.

Self-centering chucks

A chuck in which all jaws move to or away from the workpiece and maintain on common center.


A Chuck/expanding arbor with an integral pneumatic or hydraulic power cylinder.

Soft jaw

Top jaw blank that can be machined to specific dimensions Soft jaws are mounted to the master jaws.



Total indicator reading.

Top Jaw

The component that clamps the workpiece and is mounted on the master jaw.