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Hellbender
10-31-2003, 11:49 AM
Does this only work because of the laminated material? I read the description of how it works, would it work the same on a homogonius mass?

http://briananddebbie.com/images/Backyard%20Science/Quarter%20Shrinker/pulse_dischar ge.htm (http://briananddebbie.com/images/Backyard%20Science/Quarter%20Shrinker/pulse_discharge.htm)

HB

[This message has been edited by Hellbender (edited 10-31-2003).]

Evan
10-31-2003, 12:00 PM
It may not be exactly machining but it cetainly is metalworking. The technique is used in industry to, among other things, shrink hydraulic fittings on to hoses. The laminations have nothing to do with it. It is caused by eddy currents induced in the metal that are the same in magnetic polarity as the external magnetic field.

[This message has been edited by Evan (edited 10-31-2003).]

Forrest Addy
10-31-2003, 01:31 PM
I read a NASA paper in the '70's on "High Energy Rate Metal Forming" that discussed among other techniques this one.

As a sidebar, we have a local outfit out in the boondocks that explosively bonds aluminum plate to steel up to 10 x 40 ft.

I think the process goes like this: They place the thoroughly cleaned steel plate on top of a thick chunk of battle ship belt armor, sprinkle on a scatter of a separating agent (I hear it's cracked wheat) to maintain the critical accelleration distance. The place the aluminum plate on the steel and roll out a sheet of 1/4" explosive. To the end they attach a "plane wave generator" an explosive gimmink that sets off the end of the esplosive sheet all at once. And poof! A 5,000,000 PSI wave travles the length of the work at 20,000 ft per second accellerating the aluminum to the steel as sonic velocity. The impact bonds interlocks the aluminum with the steel to a joint having the strength of a fusion weld.

This stuff is used to attach aluminum deck houses to steel decks on warships and other applications. They do it on a smaller scale scale to bond most any other material you can imagine.

ibewgypsie
10-31-2003, 07:08 PM
Linemen blowing (connecting compression crimps) electrical high voltage connections use a similar technique. Thou I have never done it, I have jumped quite a few times when others did.

My forte is instrumentation and controls. Not sure what the charge is, or how it is attached.

David.

Arcane
10-31-2003, 09:01 PM
ibewgypsie, the explosive connectors I used to use on the HV power lines didn`t fuse anything together in the manner that the other gentlemen described, they simply used an explosive charge to drive a wedge inside the sleeve to mechanically grip the ACSR. Those sleeves were expensive but neat to use. We did have to securely wrap the conductor outside the sleeve ends to prevent birdcaging when the charge went off even though it was a small charge, as explosive charges go.

Rustybolt
10-31-2003, 09:55 PM
This is a little off topic, but it is a different kind of machining. I was reading a magazine put out by MIT. In it was an artical about making parts without machining as we know it. Parts can be made of either plastics or metals. The material is laid out in layers and each layer is irradiated. charged or microwaved etc. binding the material. The layers are built up until the finishied part is completed.
They mentioned that machines are already doing parts for bone grafts and various metal alloys for NASA rocket motors. Either one off or dozens at a time. They mention that complex shapes are easier to maker with this method and there is virtually no secondary work.
They mentioned that many of these machines have come down in price from 100s oif thousands of dollars to 30 to 50 thousand.
personally. I find this almost since fiction like, and I can see that manufacturing in the future will be very technologically demanding, with few of the skills of guys like us required.

wierdscience
10-31-2003, 10:23 PM
To me this looks like something that would put an obituary on the front page!

andy_b
10-31-2003, 11:14 PM
rustybolt,

a friend of mine used one of these set-ups. yes, he said the price was coming down close to $30,000. the way it worked was you had a liquid that was sensitive to UV light. in the center of this tub of liquid was a pedestal that could be raised or lowered. the pedestal started several .001s below the surface of the liquid, and the UV light was used to "draw" the first layer of what you were trying to build. the pedestal was then lowered another few .001s and the next layer was "drawn". the UV light caused the liquid to harden, and as each layer was drawn, a solid shape was formed. so you're probably thinking that a sufficiently smart CNC machine could do this right? nope. the cool thing about this process was that you could build a hollow shape with no openings in it. of course, i don't know how you got the remaining liquid out of it. it was also capable of building a captive form arrangement where one item was inside another (sort of like the old woodcarver model of a ball inside a wooden cage).

andy b.

PolskiFran
11-01-2003, 12:22 AM
Seems like a nice kid. I hope he stays alive for awhile(I read about the accident).
Frank

Rich Carlstedt
11-01-2003, 01:12 AM
That work is called "Rapid Prototyping"
and it has been around since the mid 80's.
It does make very complicated parts and can do the ball in a box typr of construction.
It is usually done for patterns for casting out of a metal. It does NOT produce metal parts. I have seen a ball bearing made with the balls in the race...complete...out of a resin material(for display !)
Problems are in the surface finish...about equal to what a bastard file produces in bench work...but they will solve that eventually

Evan
11-01-2003, 02:23 AM
The name I like for those 3D prototyping machines is "The Santa Claus Machine". Make anything to order.

Rich, they do make metal finished parts. You haven't been keeping up. This is now a production process fully capable of making end use metal parts, especially complex injection molds or even gears, material can be stainless steel if needed.

See here for an overview of the available processes:

http://www.autofieldguide.com/articles/090101.html

Rustybolt
11-01-2003, 11:33 AM
What Evan said. They claim the part goes directly from the machine to the rocket motor, or whatever. I can see where this easily replaces investment casting. Also complicated parts machining. We live in exciting times. I ,for one, would like to see one of these in operatiion.


It only means cheaper used tooling for the rest of us.LOL

Steinmetz
11-02-2003, 01:10 AM
BACK IN THE 1960/ EARLY 70'S,i USED TO TAKE MY LITTLE KIDS SWIMMING IN A SMALL LAKE/RIVER (CALLED lAKE INEZ)
Pompton lakes NJ. Across from where weswam, was a large tract of land owned by The dupont chemical company. Years before that They manufactured munitions at their plant
Although there were many Danger/ Do not enter/keep out signs all over 'Our" side of the river, we were courious about the scattered remains of outbuildings that obviously suffered from explosions.
No rooves Some, just foundations some with recwnt damage. At one point directly acrossfrom our vantage point, here was an Adit With flashing lights and BIG Warning signs. Once, the lights flashed and a shrill bell rang then, Whump!The ground shook and all we heard was a deep muffled sound The lights turned green and a different sound eminated from the spot. Over that summer, we experienced several of these events> It turned out they were experimenting with a New process caled explosive cladding Huge sheets of dissimilar metals were suspended vertically and an explosive charge set off. Bingo! The stuff they make quarters and dimes out of. . After reading your post on this subject it prompts me to Google up more facts about it.

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STEIN

Peter S
11-02-2003, 06:33 AM
Rustybolt,

If you are talking about parts used in engines etc, I don't think that is rapid prototyping, but probably something like TMC, titanium metal matrix composites, pioneered by Rolls-Royce in 1990's for use in gas turbines. Uses silicon carbide fibres to reinforce the material. Good for compressor blades and one-piece compressor blades and discs.
In one method the metal coating is applied directly to the silicon carbide fibres using an "electron beam physical vapour deposition process". Fibres are passed continuously through a vapour cloud above a molten pool of titanium alloy.

If you read a book like Bill Gunston's "Jet and Turbine Aero Engines", you will find many fascinating materials explained, (though not the above) in fact he says "we are firmly on the road towards non-metallic engines". Ceramics and powder metallurgy are used, for example, turbine discs made from powder, needing little finishing work except broaching the blade slots.
Also single-crystal casting for turbine blades is another amazing process.
I guess none of the above fit the description of "machined".

Crashtest
11-06-2003, 02:44 PM
FYI. just happened to run across this article on the web. Interesting. Hope the link works.

http://www.popsci.com/popsci/science/article/0,12543,490445,00.html

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Without knowledge we stumble blindly through the universe.

Hellbender
11-06-2003, 06:51 PM
Looks like a much simpler way to do it.....

Thanks for the link.

HB