The radial run-out accuracy of clamping chucks for a chip thickness in the range of a few thousandths of a millimetre must be almost zero, as only this can achieve good surface finishes with long tool life at maximum spindle speeds. In addition, it must be ensured that any contamination due to micro-particles is excluded. Another important topic for machining in the miniature sector is the supply of coolant. Too much cutting fluid means complex downstream part cleaning, while too little or no cooling leads to a loss in quality and productivity.
At Mapal, additive manufacturing by selective laser melting is now used in all product areas. Thanks to this process, the company has succeeded in manufacturing chucks in miniature format with an HSK-E25 connection for the direct clamping of tools with a diameter of 3 mm.
In order to guarantee radial run-out accuracy, Mapal has integrated clamping chamber systems into the newly developed chucks that fit snugly against the tool shank. The systems are equipped with dirt grooves to displace microscopic particles, while the required balancing value is guaranteed thanks to internal balancing geometries, including support structures that also optimise the weight and strength distribution. Overall, the small format chucks can achieve more homogeneous and spindle-friendly acceleration and deceleration for the entire tool system.
Thanks to additive manufacturing, Mapal has succeeded in equipping the clamping chucks for the miniature sector with decentralised coolant outlets. Using parameters such as coolant pressure, setting dimensions and spindle speed, these optimised outlets are designed in such a way that they convey the lubricant directly to the cutting point.
The 3D-printed chucks also open up additional possibilities for workpiece clamping. For example, the external hydraulic technology can be used for clamping hip joint balls. Specially shaped chip flutes inside the chuck and a special external geometry ensure that the balls are clamped precisely yet gently.
