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Magnafluxing,non destructive testing of blades


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Hi all, I was looking at an old copy of JSS Newsletter and came across this.

Magnafluxing, the blade is magnetized with a powerful magnet then sprayed with oil that contains magnetic particles .The magnetized particles align as the blade now acts as a bar magnet.Any crack acts as a separate bar magnet.One can see the magnetic material collect in the cracks/flaws ones below the skin also show with this method.Nie crystals form their own bar magnet as well . These can also be seen in this method

from JSS Newsletter vol,38,No6 ( Doug Blain )

is this useful for flaws and has someone seen this work ? thanks

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Hi Ken, So its big bucks to set up ? this was interesting as it was thought to pick up flaws below the skin. Now if I was going to get a sword polished it would be good to know what going below the skin so excuse my lack of knowledge on this is it not possible to use a strong electromagnet and make some sort of home version of this just a passing thought ?

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Well, it's been the better part of 40 years since I worked on reactors, Jim, so I'll assume that price has dropped at least a bit.

 

A quick eBay search offers a Magnaflux testing machine for only $9000 (http://www.ebay.com/itm/Uresco-Magnaflux-testing-machine-just-out-of-a-tech-school-real-clean-md-3505-/300715635220?pt=LH_DefaultDomain_0&hash=item46040c7214), so maybe if you're testing a Rai or Kiyomaro blade, maybe this would be in your budget...? That's actually about 1% of what I remember them going for - such a deal!

 

Ken

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Ken, 9k is not that bad if you are a polisher or offering this as a service (just gos to show you can get just about anything on eBay ;) ) but would like to see if this is a working method for checking a blade before you put out that amount of cash. Now you would think if it was a good method we would have heard of it before now as this came from a old JSS Newsletter, but you will never know if you don't ask. Maybe someone on the board may get a chance to give this a go.

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Well, the process of running a Magnaflux test isn't all that difficult. You brush on a dye penetrant, run it through the equipment, & then examine the blade closely with ultraviolet light. But getting the penetrant off/out of the blade isn't particularly easy, & then you're left with a highly-magnetized blade. And the process materials (penetrant & removant) aren't cheap, either. Not sure if a togishi would want to go through all that, Jim. I'd think the process would be more suitable for checking the structural integrity right after quenching, don't you?

 

Ken

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Hi Ken, The only reason it had me interested was it was in a peace on polishing/restoration but did not go in to much detail.So you are

probably right not much use at the moment unless its something special. But its worth keeping eye out for technology that can help us make better decisions. thanks

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FYI; The following document says that Koa Isshin blades were inspected by magnafluxing.

 

"...... 製品検査は、鉄道研究所岩竹氏の好意により、磁気探傷器を用いたので、肉眼で見えない傷を発見することが出来た。......"

Ref. http://www.k3.dion.ne.jp/~j-gunto/gunto_060.htm

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This would be effective in detecting any underlying flaws in a blade, and there's no need to go buy a magnaflux machine. Just take it to a metal shop that rebuilds engines. I just had my 440 block magnafluxed prior to boring and rebuild and it ran about $150. You might find someone willing to do it for less, simply because it's a lot simpler object than an engine block, and you might find someone curious enough to do it for free. Just ask to be there when they do it, or get a printout of the flux lines so you've got something to analyze. This is just a hunch, but I would guess the force lines should generally be in one direction; anything perpendicular would be bad. Let me know if you do it, I'm curious how it would turn out.

 

Forgot to add that a decent shop will demagnetize the object if you ask and they typically clean it up for you as well. Any good shop will have everything they need to hand you your hunk of metal (engine, sword, whatever) back in at least the condition you gave it to them. You may actually loose some rust in the process, so if you're concerned about your tang, this is something to consider.

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Hi,Nobody thank you for the link on manchuria railway swords,

Melissa,also thanks did not know they are using it on engines,I had the thought if it can see deep and if the force lines go in one direction it may be able to see the Steel construction and if its kobuse or three layers construction for instance. It seems that it does have a use in swords.

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