High-precision, high-efficiency machining realized by the DDRT-260 rotary table equipped with Mori Seiki's original technology DDM(TM)

The DDRT-260, an innovative rotary table that employs Mori Seiki's original DDM™ (Direct Drive Motor) and offers high-efficiency 4-axis machining on existing vertical machining centers, has received high praise from many customers ever since its debut last June.

The DDRT-260 achieves process integration through multi-face machining, even for machining with many different processes that usually must be performed one by one on conventional machines. It also allows a vertical machining center to serve as a horizontal machining center, which contributes to greater productivity per unit area.

Mori Seiki will release more rotary tables with different table diameters <200 mm, 300 mm and 400 mm (7.9 in., 11.8 in. and 15.7 in.)> in addition to the current model, with that of 260 mm (10.2 in.). The following column discusses the superior nature of the DDRT-260, when compared with a conventional rotary table which uses worm gears.

The world's fastest rotary axis drive system DDM™

Transmitting the drive power directly to the rotary axes without using gears eliminates backlash. Compared with conventional worm gear systems, this dramatically improves transmission efficiency and offers high-speed feed.

♦ Rotational speed of the table

♦ Indexing time (clamping, unclamping time are not included)

♦ Positioning accuracy

♦ Motor power consumption (No load/ Test cycle: 1 hour)

DDM™ can transfer 100% of the motor output to the table, while worm gear systems transfer only 50-70% of the output to the wheel. Moreover, DDM™ can significantly save its power consumption as the power is turned off when the brake is applied.

Thermal displacement
Worm gear systems consist of many parts that, due to friction, generate heat over the contact surfaces between parts, and especially over the contact surface between gears and wheels. The DDM™ dramatically reduces the heat generation by transmitting the drive power directly to the table, and offers stable machining.

♦ Displacement <actual results>

Thermal displacement data collecting condition
◊ 90° rotation + 30 sec. dwell		◊ Repeat these two steps alternately
• Cold start	• No axis travel	• 10 hrs. continuous running	• Measure every 10 min.
* Measurement is based on ISO230-2.

Roundness

♦ Circular arc cutting by the X-, Z- and A-axis

Material <JIS>	A7075 (Aluminium)
Tool	R6 ball-end milling
Workpiece size	φ150 mm × 150 mm (φ5.9 in. × 5.9 in.)
Spindle speed	10,000 min^-1
Feedrate	2,000 mm/min (78.7 ipm)
Feed per turn (helical interpolation)	0.5 mm (0.02 in.)

♦ Measurement results

* The cutting test results indicated are provided as an example. The results indicated may not be obtained due to differences in cutting conditions and environmental conditions during measurement.