When dealing with workpiece diameters measuring 3 inches or less, a CNC collet chuck could be the best option for your application instead of the standard three-jaw chuck. In fact, using a collet chuck is so beneficial for parts of this size range that many lathe manufacturers and machine tool distributors now allow customers to purchase their machines with a collet chuck already installed as the standard workholding device. A CNC collet chuck mounts to the working side of the CNC lathe spindle in the same manner as a three-jaw chuck and uses the machine’s existing hydraulic cylinder and drawtube for actuation.
Why are CNC collet chucks for workholding so advantageous for small parts? The reasons are numerous, but the most obvious is the fact that there is an additional tool clearance provided by a collet chuck’s streamlined shape and reduced nose diameter. This setup enables machining to take place much closer to the chuck, providing maximum rigidity and better surface finish.
Small-diameter parts’ lower mass and symmetrical geometries enable them to run at higher speeds than conventional three-jaw chucks. Also, three-jaw chucks have only three points of contact, whereas a collet chuck and collet offers 360-degree support. This additional contact helps reduce the chance of part slippage, and also plays an important role in the machining of tubes and thin-walled parts. This support also ensures that the barstock remains on centerline for concentric re-gripping after being advanced by the bar feeder.
To read about more advantages to using CNC collet chucks, visit “Understanding CNC Collet Chucks.” http://www.productionmachining.com/articles/understanding-cnc-collet-chucks
To learn about ways to determine the most suitable workholding for a job, read “Proper Workholding Selection.” http://www.productionmachining.com/articles/proper-workholding-selection