Workholding definitions

accuracy

The accuracy of a chuck/expanding mandrel measured in mm 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.

actuator
A device that clamps the chuck or expanding mandrel through the aid of pneumatic or hydraulic cylinder.

chuck
A chuck is a specialized type workholding device usually used to hold a rotating workpiece (such as the bar or blank in the headstock spindle of a lathe)

clamping cylinder
See actuator.

collet
A collet is a holding device—specifically, a subtype of chuck—that forms a collar around the object to be held and exerts a strong clamping force on the object when it is tightened, usually by means of a tapered outer collar to grip the work piece. 

collet chuck
A device that uses a collet for workholding. 

compensating chuck
A chuck in which the jaws individually locate their gripping diameter without altering the position of the workpiece.

 

crank Shaft Machining Chuck

A special power chuck designed for crank shaft Eccentric Turning and milling operations. This chuck can be tailor made to suit machine. Crankshaft is held between centres of RH and LH chuck. Aligning jaw of the chuck facilitates job clamping. Chucks are actuated by hydraulic cylinders. 

dead length
The action of gripping a workpiece without changing its axial position and uses the face of the spindle as its locating surface for the inner collet. 

diaphragm chuck
A chuck that uses the deformation of a flexible material to grip a workpiece and is ideal for thin walled components. Diaphragm chucks are primarily used for light accurate turning, fine boring, facing and grinding operations.

 

expanding mandrel
A workholding device which is used for internal diameter clamping of component to machine in a single setup

 

face driver
Face Driver allows roughing and finishing operations completed in one clamping and you will able to machine the entire length of the workpiece in one operation.

 

first operation chuck
A workholding device designed to grip on unmachined castings, forgings or bar stock.

 

fixture
A work-holding or support device used to securely locate or support material, workpiece or a tool during machining operations ensuring that all parts produced using the fixture will maintain conformity and interchangeability.  Usually custom designed to hold a specific workpiece. 

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

 

mandrel
see expanding mandrel

 

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

pull-back chuck
This Chuck is ideal for the finishing operation, it simultaneously grips and pulls the piece part back against a workstop. The Radial pull back function of the chuck ensures a positive resting of the component after clamping 

repeatability
The repeated accuracy of chucked workpieces, especially the workpieces with a relatively higher length/diameter ratio used for production of duplicate parts.

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
A workholding device designed to grip on previously machined surfaces.

self-centering chucks
A self-centering chuck, also known as a scroll chuck in which all jaws move to or away from the workpiece and maintain on common center.

 

self-contained
A Chuck with an integral or built-in 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.

 

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

GMT Twist Finger Chuck

FINGER CHUCK : GMT has developed specialized chucks for second operations where radial clamping is not possible. A suitable locator is used to locate the component center. The fingers located in a rod, which has a helical groove ensure that the component is flat against the chuck. This enables loading yet ensures accurate location. GMT-make hydraulic rotating cylinder is used to move the chuck fingers swings in and clamps the component in a single motion. Actuator pin is located on helical groove for actuating the finger. Fingers during de-clamping lift and swings out for component unloading and loading. The chuck firmly clamps the component without any distortion or surface damage.
Features :

• Chuck has a locator for locating the component.
• Twist finger chucks cannot perform without locating the component.
• Fingers are located in a rod, which has a helical groove.
• Actuator pin located on helical groove for actuating the finger. Fingers during clamping and de-clamping lift, swings in and out, for component loading and unloading.

Application :
Automotive, Wheel turning, Aerospace, Aircraft, Commercial vehicles, Energy, Heavy duty machines, Defence Production, Oil, Wind generators