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Servo drives are "twice as fast as rivals"

01 October, 2006

Servo drives are `twice as fast as rivals`

Mitsubishi has launched a new generation of servo motors and amplifiers — its ninth since 1980 — with the claim that the new drives perform twice as well as their nearest rivals. Jon Sumner, who looks after the company`s servos and motion control business in the UK, says that new MR-J3 occupies one fifth of the volume of its predecessor, while delivering 260 times better performance. It is also 30% cheaper.

The new servo has a 900Hz speed frequency response — 30% faster than the previous generation, and better than almost all of its rivals, according to Sumner. The result is faster operation, greater accuracy, and enhanced productivity.

The servo`s feedback update times are 11µs in current loop mode, 22µs in position loop mode, and 55µs in speed loop mode. The motors are capable of speeds up to 6,000 rpm, and are fitted with 18-bit encoders that deliver 262,144 pulses/rev.

The amplifiers are at least 40% smaller than Mitsubishi`s previous-generation models, and the motors are almost 25% shorter. This will reduce the need for costly cubicle space and allow the motors to fit into small recesses in machines, Mitsubishi says.

Other advanced technologies built into the new drives include:

a real-time, auto-tuning adaptive filter that can suppress vibrations at high gain settings;

an automatic function that analyses, and compensates for, the effects of vibrating loads; and

a dedicated fibre-based motion network (SSCNET III) that can link 96 axes and supports transfer rates up to 50Mb/s and cycle times of 0.44ms.

The servos span ratings from 50W-55kW. All are programmed using the same Windows software which incorporates functions such as a graphical machine analyser, an oscilloscope and a high-speed sampling monitor. Sumner says that some other suppliers need three different technologies and programming systems to cover the same ratings range.

The MR-J3 was launched in Europe at this year`s Hannover Fair, and Sumner reports that initial applications are confirming the time-saving and performance claims. One application, involving 182 servomotors, used to take 40 minutes to set up — it now takes 5s. In another application, cycle times for a machine used to package sandwiches and ready meals have been cut from 1.6s to 1.2s, representing a 25% increase in output.

At present, Mitsubishi holds just 2% of the fragmented UK servo market. Sumner is confident that the new drives will help to raise this share substantially.

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