22 Jul 2024


Hydrostatic linear guides are the same size as rail guides

Schaeffler has developed a range of hydrostatic linear guides that, it asserts, combine good damping characteristics with the compact dimensions of profiled rail linear guides.

Unlike conventional ball or roller guides, hydrostatic guides have no metal-to-metal contact. The carriages move on a thin cushion of high-pressure fluid, so their guideways do not wear. They are ideal for linear motion applications in which high damping is needed at the point where the load is applied – for example, in high-speed machining and precision grinding.

To date, most hydrostatic guides have been relatively expensive, time-consuming to mount and adjust, and needed more space than profiled rail guides. However, the new INA HLE guide (above) fits in the standard design space of a profiled rail linear guide.

The lubricant film separating the components damps vibrations using the “squeeze film” effect, which reduces or even eliminates elevated resonant frequencies. The dynamic rigidity of the application is improved and higher precision is achieved in machining operations.

The hydrostatic guides have been tested extensively in customer applications. One of these involved a three-axis machining centre. The transverse (Y) axis, which guides the main spindle assembly and the Z-axis, was fitted with a 45mm rail-width hydrostatic guide. The deflection was found to be almost identical to a roller monorail guidance system, indicating that it was no less rigid.

Examining the dynamic resilience revealed a clear reduction in vibration peaks in all axes, allowing a significant increase in the maximum machining depth. Tests showed that when using monorail guidance systems, the cut would become unstable with regenerative chatter at certain machining depths. Using the HLE guides under the same conditions, the cut was stable.

Crash protection was also improved, because the pressure in the oil pockets increases as the load is applied, creating a restoring force that prevents the fluid gap from closing under a high impact load.

An integral hydraulic controller means that the hydrostatic guides are ready-to-fit and are interchangeable with monorail guidance systems.

For machine-builders, the ease of mounting will cut design and assembly costs. And, because the guides comply with ISO/DIN design envelopes for monorail guidance systems, both roller guidance systems and hydrostatic guiding elements can be used in the same machine design, supporting a variety of performance classes.