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Hard Turning and Finish 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 1000. The hybrid MikroTurnGrind 1000 combines the advantages of hard turning and finish grinding in one machine. With the MikroTurnGrind 1000, 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 is achieved, which is often mandated on sealing diameters.

"Incorporating the hydrostatic work spindle and slide systems technology from its existing Mikroturn series, Hembrug has developed a true hybrid turn/grind machine, the MikroTurnGrind 1000. A machine that achieves exemplary accuracy in both hard and finish grinding," said the spokesperson. The MikroTurnGrind 1000 utilizes a B-axis that offers optional space for a turret with eight fixed VDI 30 toolholders, an external grinding spindle with a 300 mm diameter grinding wheel as well as an internal grinding spindle. One of the grinding spindles can also be replaced by a milling spindle. The precise and stiff B-axis is arranged with a double Hirth coupling that can be adjusted in 90 positions over 270°. Operators can switch from turning to grinding at the press of a button. A variety of dresser types can be used that mount either to the work spindle or tailstock housings. The MikroTurnGrind 1000 can be equipped with an NC-controlled tailstock and one or two steady rests to support long shafts.

To provide high accuracy, the MikroTurnGrind 1000 comes as standard with a 4,000 RPM hydrostatic work spindle with runout of < 0.1 micron (TIR), and hydrostatic X- and Z-axis slides having repetitive accuracies of ±0.1 micron. "The wear-free, hydrostatic bearings ensure that the machine will continue to deliver the same level of accuracy after 20 or 30 years," said the spokesperson. 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, resulting in a small footprint of 3,850 mm (width) by 2,200 mm (depth). Total machine weight is approximately 12 tons.

A Siemens 840D SL control is standard utilizing user-friendly Danobat grinding software. The MikroTurnGrind 1000 has a swing capacity of O380 mm. When using the tailstock, parts up to 1,000 mm in length can be accommodated between centers. Swing is then reduced to 200 mm.

For more information contact:

Gary Anderson

North America Sales Manager

Hembrug Machine Tools


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