August 1, 2013
One of the unsung heroes of CNC machining is the 3-jaw chuck that is standard equipment on many CNC lathes and turning centers. The chuck is the principal workholding device and is essential for maintaining accuracy and enabling the machine tool to perform at optimum RPM.
What some don’t stop to consider is how many moving parts this seemingly simple apparatus contains, and the importance of maintaining proper lubrication of these parts. Typically, the chuck jaws open and close via the action of a piston within an hydraulic actuator connected to the chuck by a drawtube. The back-and-forth motion of the piston drives a plunger inside the chuck body to open and close the jaws so that it grips the work piece with appropriate force.
Clearly, if all of these moving parts aren’t properly lubricated, the resulting friction will develop areas of wear on the chuck. This can create out-of-tolerance parts, scrap and rework. Not to mention thousands of dollars in unnecessary expense to replace a badly worn or damaged chuck.
Therefore it is critical to maintain a regular maintenance schedule that includes daily lubrication. A few things to remember about maintaining chucks:
While all mechanical devices eventually wear, you can insure that your chucks will operate reliably and enjoy a normal lifespan by following a consistent program of proper lubrication, keeping them free of dirt and other contaminants, and setting appropriate gripping forces.