Magneto-strictive transducers are back! (or not)

Not an article as such, but hopefully of interest to readers...

Since the early 1980's, piezo-electric transducers have dominated the power ultrasonics industry. After some early reliability problems (cured largely by improvements to the electronic control systems used to drive them) they have now almost completely replaced the old inefficient laminated nickel alloy transducers wrapped in coils of PTFE insulated wire (the heat generated would melt conventional plastic insulation!).

ETREMA plans to change all that, with their new ultrasonic transducers based on Terfenol D®.

This is a special magneto-strictive iron alloy which tolerates high strains. It has been available for many years but only from laboratory-scale production. Now full production brings larger sizes and much better pricing, plus laminated blocks to reduce eddy-current losses in high frequency systems. Their new 20 kHz, 6kW transducer handles more power than any other ultrasonic transducer I know, and they are promising something much bigger in the near future...

Watch this space!

Update August 2004 (still watching)

Four years later both pages I originally linked to have disappeared. Instead Etrema now offer a system called MaXonics, delivering 3kW in continuous operation. I have to say it's a bit disappointing...

Update March 2008 (losing hope now!)

After another four years all details of the high-power ultrasonic devices have been removed, leaving a generic page with "Please contact us for a quote". Meanwhile the competing piezo-electric transducers continue to develop with ever-increasing power output. No doubt these materials have their place in lower-frequency, sub-resonant applications (actuators) but it appears to me that they're unable to compete in high-power ultrasonics. Unless of course, you know different...?

Update October 2013

I've updated the link to the only Terfenol-D transducer I can currently find on the Etrema site. No explicit power rating is quoted but based on the 250V / 10A figures on the technical data sheet it appears to be limited to 2.5kW (input).