What are the types and structures of CNC lathe chucks.

Many CNC lathes and turning centers are shipped from the factory with a standard workholding system that includes chucks, hydraulically actuated cylinders, and draw tubes. The hydraulic cylinder is fixed to the rear end of the machine tool spindle, while the chuck is mounted to the front or working side of the spindle. The two components are usually connected together by a hollow steel draw tube that passes through the spindle bore.

The collet attaches to lathes, mills, and other manual or CNC machine tools so that the collet can securely hold small diameter tools and workpieces on the machine. They feature straight or tapered shanks that attach to the machine tool spindle, and finish holes that accommodate collets. These collet chucks are compatible with specific collet styles and sizes.

CNC Lathe Chuck Type

Different types of chucks used in CNC lathes: four-jaw independent chuck, three-jaw universal chuck, combined chuck, magnetic chuck, collet, pneumatic or hydraulic chuck, drill chuck, etc. As turning skills improve and versions of various workpieces are machined, different chucks and chuck methods are constantly encountered, each with variations.

CNC lathe chuck Four-jaw independent chuck

A four-jaw chuck is an arrangement of four independent jaws with four jaws angled at 90° to each other. Here, all four jaws open independently. The rolling disc is replaced with four screws, so it is called a four-jaw independent chuck. Each jaw is made of solid steel and has three inner and one outer gripping surfaces. External gripping surfaces are used to grip larger size workpieces by reversing the jaws. Concentric circles are engraved on the chuck surface to quickly center the workpiece. This type of chuck is especially used for the installation of heavy and irregularly shaped items. The diameter of the body specifies the size of the chuck.

Universal or three-jaw chuck

The three-jaw chuck is the most commonly used chuck type lathe machine. The three jaws are usually made of high-quality steel and are inclined at a 120° angle to each other. During operation, the jaw teeth are engaged with the grass helical teeth (bevel teeth). Meshing results in a moment of all three jaws towards or away from the center of the chuck, depending on the direction of rotation of the pinion. The pinions are operated by square-headed keys called "chuck keys". This chuck is suitable for holding round or hexagonal and other similar shaped workpieces. In a three-jaw chuck, the job is automatically and quickly centered. But it has less grip because only three jaws are used, and it loses centering accuracy quickly due to wear.

Combination chuck

As the name suggests, it is a combination of chucks. It can be used either as a self-centering or as a standalone chuck to get the most out of both types. The jaws are operated individually by separate screws, or simultaneously by the scrolls. The underside of the frame is cut with teeth that mesh with the scroll, and all the jaws move radially with the screw when the scroll is rotated by the pinion.

Electromagnetic chuck

Chucks are used to hold workpieces made of very thin magnetic materials that cannot be held in ordinary chucks. It can also be used where deformation of the workpiece due to jaw pressure is not desired. The holding force of the chuck is obtained by the magnetic flux radiated from the electromagnet or from the permanent magnet introduced into the chuck.

In the "on" position, the flux passes through the workpiece and clamps the workpiece. In the "off" position, the magnets are set aside so that they are in contact with the high permeability "retainers", which short-circuit the magnetic flux and prevent it from passing through the workpiece.

collet

Collet chucks are used to hold bars in production jobs that require fast set-up and accurate centering. The chuck, which is attached to the spindle by a nut, consists of a thin cylindrical bushing called a collet with a longitudinally cut slot on its perimeter. The inner hole of the collet is cylindrical, hexagonal, square, etc. Depends on the shape of the workpiece to be passed through.

CNC lathe chuck

For many workpiece turning operations, the chuck performs the basic job of holding the job securely and reliably. These operations often present unique requirements, and as a result, a dizzying array of manufacturing and fabrication chucks have evolved to expand, grip, tighten, pull, compress, jam, and even move workpieces off-center. It is especially important to know which chuck to use for machining the workpiece, especially since most chucks are designed for specific applications, so they each have advantages and disadvantages. Understanding chucks will enhance your knowledge and improve the safety of your workshop environment.