New high-speed spindle offers up to 65% reduction in vibrations

The new high speed spindles successfully reduces natural vibrations by up to 65 % in comparison with standard spindles. This makes for more cost-effective workpiece machining, since components can be worked consistently with greater cutting depths and therefore higher material-removal rates. Improved surface quality is obtained at all speeds – not only for rough-machining, but also during the finishing process and grinding.

The new spindles are characterised by a vastly improved dynamic stiffness. Thanks to the hydroviscous system, damping of natural vibrations is enhanced considerably. In the axial direction, it was possible to achieve an improvement in dynamic stiffness, for example, of up to 135 %. This results in significantly reduced natural vibrations in the machining process, enabling the production of components of very high quality.

An investigation by the Laboratory of Machine Tools and Production Engineering (WZL) at the Rhine-Westphalia Institute of Technology Aachen concluded that it was possible to double the minimum stable cutting depth at speeds between of 10,000 and 18,000 rpm with the high-speed spindle HCS 280 – 18000/60 with HSK-100. When using spindles with hydroviscous damping, consistently good surface results were obtained up to a plunge depth of 6 mm – even at unfavourable speeds. Conversely, a depth of only 3 mm was achieved using a standard spindle under the same conditions.

Surface quality was also noticeably improved for internal cylindrical grinding and surface grinding. Under production conditions at GMN’s own manufacturing facility, for example, a hydroviscously damped spindle produced a roughness of only 0.89 µm – compared with 2.36 µm using standard models.

The new high-speed spindles are independently driven by their own small, energy-saving hydraulic power unit. In addition, the bearing preload of the spindle can be controlled via the oil pressure. In this way, the rigidity of the spindle can be modified and therefore its behaviour optimised depending on machining task, speed, and tool. Increased preload can, for example, be used to significantly improve spindle performance at lower speeds.

The new spindle models with hydroviscous damping are available for machining centres for use in milling and drilling operations as well as for grinding machines. Since they are structurally identical to the standard models, they can also be easily retrofitted to existing machines.