Ways to maintain your clamping vices

The negligence during lubrication and maintenance lead to a continuous reduction of the required lubricating film on the jaw guidances and lathe chuck mechanics, which ensure proper function. Porous seals and penetrating dirt also slows the process down. The clamping force and the chuck's precision is reduced, which will lead to malfunctions during jaw changes. This leads to extended set-up times and disturbances in production.

Accidents and damages should be avoided In order to avoid such failures, experts in the field of clamping technology are recommending the regular lubrication of the workpiece clamping vises, and to run a complete maintenance check on them once a year. The lubrication cycles depend on the used clamping vise: In the case of low-maintenance lathe chucks, it is enough to regularly control the oil level. Similar to this would be the power lathe chucks which are equipped with a central lubrication, or if a quick-change pallet system is actuated with lubricated air. In both cases it is enough if the clamping systems are regularly controlled on proper function. According to DIN EN 1550, the manufacturers of clamping equipments are principally bound to indicate data on the correct maintenance and the intervals between two static clamping force measurements in their operating instructions. Normally the required lubricating cycles of the individual lathe chucks are also defined in the operating manual.

Lubrication is not enough During lubrication the operator should ensure that every surface will be lubricated evenly. The narrower the fit of the assembly part, the higher the press-in pressure of the lubricant has to be. Optimum results are achieved if a grease gun is used.   In order to avoid imbalance, every segment of the chuck has to be lubricated evenly. Then the clamping piston should be moved several times along the whole clamping stroke so that the grease will be evenly distributed on every surface. In order to permanently maintain the clamping force, the piston should be moved several times to its end positions and back after every 500 clamping strokes. Thereby the lubricant which has been pressed aside during the clamping operation is fed again to the pressure surfaces. Moreover, the serration should be cleaned and lubrified at every base jaw change.

There are substantial differences between the offered grease for lubrication. Unsuitable lubricants may have a negative effect on the chuck's functionality, as well as the clamping force, the coefficient of friction, and the wear behaviour. Whereas the user will achieve a particularly uniform, and therefore optimum acting lubricant films if high-quality greases are used. The amount of contained solid substance is a quality criterion of the lubricant. Particularly high-quality greases contain extremely small solid particles, and even when they are used for high-performance clamping force blocks or precise and flexibly used wedge bar chucks they can achieve their full effect.

Beside the regular lubrication the lathe chucks should be detached from the machine spindle, disassembled, cleaned and completely lubrified once a year. After assembly, the clamping force should be measured with a load cell to ensure that the clamping force is available in its full extend. This type of measurement should be always done in the same chuck condition which comes up to the latest clamping application. If top jaws with clamping steps should be used, it has to be measured in the same step, as it is clamped later. In case of high working speeds it would be wise to additionally control the operation clamping force by testing it in a simulated operational environment.