Jena Tec is selling GMN Nuernberg's high-speed and high-frequency machining spindles in the UK. GMN's UHS series provides a robust oil-lubricated grinding spindle for speeds up to 250,000rpm, coupled with an exacting stability and geometric tolerance. A minimised oil/air dosing system provides the correct amount of lubrication to the spindle and reduces maintenance and running costs throughout its life. Jena Tec's automation division can supply the UHS series from GMN, including integration or retrofit to existing machines.Processing small internal diameters with optimum cutting speeds requires high rotational speeds. New GMN spindle ball bearings with high-speed characteristics permit 250,000 revolutions per minute, for instance, with high spindle rigidity and load capacity. Optimised lubrication of high-speed spindles offers great potential for increasing performance, while on-demand minimal lubrication lowers oil consumption and increases service life. In future, integrated data loggers will monitor the condition of the spindle, store the operating parameters and guarantee high availability.
GMN has a long track record of supplying a wide range of high-frequency spindles of up to 180,000rpm. GMN grinding spindles can grind small internal geometries at up to 250,000rpm. The GMN grinding spindles used for this purpose have a comparatively large and rigid mounting and a powerful synchronous motor. Consequently, they are not only suitable for special applications at maximum speeds but can also be used flexibly and efficiently in a relatively large rotational-speed range. Ball bearings with permanent grease lubrication or oil/air lubrication are often used in machine-tool spindles.
Both methods have disadvantages that can be overcome using a micro-dosing system combined with appropriate lubrication strategies. Compared with today's oil/air lubrication method, a significant reduction of the lubricant quantity necessary can be achieved and the systematic performance limits of grease lubrication (such as limited usable life of grease at high temperatures and speed) can be exceeded. Minimising lubricant quantities makes ecological and economic sense. It facilitates the integration of an oil reservoir into the spindles and ideally requires no more external components.
The problems associated with waste-oil disposal are also defused. Operating costs of machine tools can exceed acquisition costs several times over if calculated over a normal life cycle. These costs are therefore a decisive factor for many users when making an investment decision. An integrated lubricant cartridge means that high-maintenance external components can be dispensed with. The lubricant reservoir only needs to be replaced at relatively long intervals. An almost instant dosage of lubricant ensures the adjustment of the lubricant quantity matches demand based on the exact measurements of the bearing.
This increases reliability and efficiency of the bearing and reduces the quantity of the lubricant needed. Spindles are becoming more intelligent. Miniaturised electronics integrated in the spindle store the sensor signals, process them and report any exceeding of critical values to the overall machine-control system. Important operating data can be accessed during the entire running time of the spindle and can also be analysed with regards to optimising the process, machine and spindle. These intelligent systems can also monitor bearing condition and detect early damage. Evaluating temperature sensors, position sensors and vibration sensors will increase precision and productivity of the production process.
