Electromagnetic fields as cutting tools

December 1, 2009

(PhysOrg.com) -- The bodywork on motor vehicles must be sufficiently stable, but processing the high-strength steels involved -- for example punching holes in them -- can prove something of a challenge. A new steel-cutting process will save time, energy and money in the future.

Squealing tires and the crunch of impact - when an accident occurs, the steel sheets that form a ’s bodywork must provide adequate impact protection and shield its passengers to the greatest extent possible. But the strength of the steels that are used throw up their own challenges, for example when automobile manufacturers have to punch holes in them for cable routing. Struggling to pierce the hard steel, mechanical cutting tools rapidly wear out. And because they also leave some unwanted material on the underside of the steel (burr, as the experts call it), additional time has to be spent on a finishing process. One possible alternative is to use lasers as cutters, but they require a great deal of energy, which makes the entire process time-consuming and costly.

Working together with a number of partners including Volkswagen, researchers at the Fraunhofer Institute for Machine Tools and Forming Technology IWU in Chemnitz have come up with another way to make holes in press-hardened steel bodywork. Dr. Verena Kräusel, head of department at the IWU, explains: “The new method is based on electromagnetic pulse technology (EMPT), which was previously used primarily to expand or neck aluminum tubes. We’ve modified it to cut even hard steels. Whereas a takes around 1.4 seconds to cut a hole, EMPT can do the job in approximately 200 milliseconds - our method is up to seven times faster.” Another advantage is that it produces no burr, thus doing away with the need for a finishing process. Stamping presses become superfluous, and no costs arise from the need to replace worn-out parts.

The pulse generators comprise a coil, a capacitor battery, a charging device and high-current switches. When the switch closes, the capacitors discharge via the coil within a matter of microseconds, producing a high pulsed current. The coil converts the energy stored in the capacitors into magnetic energy. To be able to use this process to cut steel, the researchers simply had to modify the coil to ensure the resulting electromagnetic field is strong enough: the pressure with which the field hits the steel must be so high that it forcibly expels the material from the sheet. “The impact pressure on the is approximately 3,500 bar, which equates to the weight of three small cars on a single fingernail,” says Kräusel. PSTproducts GmbH in Alzenau provided the original EMPT system. With regard to the customer demands the researchers develop now the coils for various cutting geometries.

Provided by Fraunhofer-Gesellschaft (news : web)

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not rated yet Dec 01, 2009
rated 5 if the cutting coils had been shown
5 / 5 (1) Dec 02, 2009
This device will make for a good handgun that shoots EMPT rather than bullets. It can be noiseless and not affected by wind. I do not think a Faraday cage will protect you :)
But obviously I do not want to see any casualties of this new device.
Be nice to the future robots as they might go EMP on you.
5 / 5 (1) Dec 02, 2009
No, it could shoot bullets. They'd go really really fast.
5 / 5 (1) Dec 02, 2009
Making this thing fire bullets would make a Rail Gun. I think it's the same concept used on Rail Guns being tested on new war ships where they accelerate a shell to extremely high speed with a magnetic field.
not rated yet Dec 02, 2009
Given probable field dispersion, this is more of a 'shaped charge' device...

Would be handy for making mounting holes in 'toughened' truck frames. I've seen vehicles with warning stickers that heat-cutting / welding is not allowed due to the resultant strength loss...

I am NOT about to speculate on possible military & criminal applications...
not rated yet Dec 02, 2009
Anyone else get "sore" fingers on the "three cars on a fingernail" part? After having a walkway slab crush my finger when i was a kid, i don't even want to imagine the pain of 3 cars smashing in to a finger..

Amazing work though, could probably be used in a lot of other places.
As for the driving force thing, that could probably be used for driving nails in to tough materials.
Mind you, the material could become damaged by the sudden high force ripping through it.
If it was for concrete, the cracks could be refilled fairly easily i guess.
Or, as mentioned, Rail Drivers. RD + armor-piercing bullets = one powerful weapon.
5 / 5 (3) Dec 02, 2009
Jeez..Someone makes a great discovery and 5 out of 6 people only can think of how to use it to kill others.

Sometimes I really think scientists shouldn't publish at all. The general populace seems not to be mature enough to handle the results.
not rated yet Dec 02, 2009
What happens to the steel that was the hole?
5 / 5 (1) Dec 03, 2009
The really frightening thing is not what five out of six dreamers can blog with access to un fait accompli, it is what at least one motivated actor has has already implemented. The general populace contributes nothing but useless opinions (like this one)and purchasing power to buy home gadgets, offshoots from scientific research. Fewer than one in ten thousand people actually contribute anything to science. The sole useful product from the mass of humanity is love.
not rated yet Dec 03, 2009
So will the electromagnetic pulse fry all the electronics around it? (That is, except for the hardened stuff, like Toughbooks) Can it be focused to minimize these effects? And how far will the more dangerous effects of the EMP propagate?
not rated yet Dec 05, 2009
this wouldnt work as a weapon. they mentioned that the piece of steel gets cut out, but the dont mention what happens to it. I'm sure, due to the amount of energy involved, the piece that is removed would be molten and deformed, NOT what you want to happen to a bullet.

Also, Hemo, this isnt the Compton-Effect EMP that you're thinking about, this is a very directional localized pulse, most of the energy is absorbed by the metal in cutting and heating it. The range of propagation is gonna be real small... like 1/r^2 small....
not rated yet Dec 06, 2009
They say that the holes won't require machining, which leads me to believe it melts the metal instead of cutting/puncturing it.
not rated yet Dec 07, 2009
Too bad the article doesn't disclose how much energy is required to punch the hole, versus lasers and machine tools.

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