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Hard Turning and Fine Grinding in One Machine

"The manufacturing industry is setting a higher and higher bar in terms of productivity and product quality," said a Hembrug Machine Tools spokesperson. "Sub-micron accuracies on hardened steel workpieces, such as bearing rings and drive shafts, are no longer an exception but the rule. In addition to cylindrical grinding, it is also possible to meet these requirements with a high precision hard turning machine. The hard turning process offers many advantages, especially for workpieces with complex shapes requiring a combination of external and internal machining. The process is also easy to set up and change over. However, sometimes surface structure and quality cannot be achieved through hard turning only."

For this reason, the Dutch hard turning specialist Hembrug Machine Tools, part of the Spanish precision turning and grinding machine manufacturer Danobat, has developed the MikroTurnGrind Vertical, which complements the existing horizontal MikroTurnGrind 100 and 1000. The hybrid MikroTurnGrind Vertical combines the advantages of hard turning and fine grinding in one machine and is suitable for large workpieces up to a diameter of 1,000 mm. This way manufacturers can apply the most suitable process for each surface to be machined, all in one set-up without the need for multiple machines. In addition, with grinding a turn-free surface finish can be achieved and is sometimes required or specified.

"The MikroTurnGrind Vertical is a true hybrid turn/grind machine," said the spokesperson. "It achieves exemplary accuracy in both hard and fine grinding."

The machine utilizes a 46 position tool changer for storing the turning tools and grinding wheels. An automated system is used for change-out of the turning ram, grinding spindle and/or milling spindle. The receiver for the turning ram or grinding spindle in the Z-axis consists of a Hirth coupling with long term accuracy. The grinding spindle, with speeds up to a max. of 12,000 RPM, can be adjusted to an angle of +/-115°.

To help ensure high accuracy, the MikroTurnGrind Vertical comes as standard with a 800 RPM hydrostatic work spindle with runout of < 0.2 micron (TIR) and hydrostatic X- and Z-axis slides having repetitive accuracies of 0.2 micron. Wear-free hydrostatic bearings help ensure that the machine will continue to deliver the same level of accuracy after 20 or 30 years. Thermal stability is achieved by cooling critical machine components by maintaining oil temperature at 20 °C ±0.1 °C. The hydraulic power unit, chiller and electrical cabinet are integrated within the guarding structure. A Siemens 840D SL control is standard utilizing user friendly Danobat grinding software.

"Hard turning offers advantages, particularly for complex shapes and where a combination of internal and external machining is required," said the spokesperson. "Of course, the process is easy to set up and change over. On the flip side, grinding offers advantages where surface finish textures together with process mandates specify that grinding must be used for finishing. Additionally, some of the exotic materials, such as Inconel, are better suited for grinding. A hybrid process therefore offers great flexibility, accuracy and economic advantages, especially for manufacturers of small- to medium-sized production runs over a wide variety of workpiece types. The MikroTurnGrind Vertical can replace multiple time-consuming and labor-intensive machines/processes with a single machine."

For more information contact:

Gary Anderson

North America Sales Manager

Hembrug Machine Tools, USA


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