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loose nut
12-17-2013, 07:16 PM
All of a sudden I am getting magnetized chips when I'm milling a bit of steel, ordinary crapolium (A36 or 44w) nothing special. Has anybody else had this happen and is there a way to stop it.

JoeLee
12-17-2013, 07:48 PM
Yes sir, I've had it happen many times before. Not sure what the cause is, friction and static perhaps. It seems to happen to the harder steels from what I've noticed.
What annoys me more than chips sticking to the cutter is when they stick to the tips of your calipers.

JL...............

darryl
12-17-2013, 09:16 PM
Yes, it's happened to me- not often, but it's not a rare event either. So far I haven't come up with a good explanation, at least not one that survives a good analysis. Maybe nano-science can come up with the answer.

bobw53
12-17-2013, 09:22 PM
Cut aluminum instead.

JoeLee
12-17-2013, 09:51 PM
I'm going to have to guess that the friction between the cutter and the material being cut is creating a static charge which in turn is magnetizing the chips, sort of like an electro magnet. Ever wonder what causes your mics or other tools to become slightly magnetized even if you never had them near any magnetic field. Ball bearings can become slightly magnetized also, same reason friction.
I'm sure someone else can give a more scientific explanation of why this occurs than I can.

JL.................

jlevie
12-17-2013, 10:40 PM
My guess is that the stock is slightly magnetic to begin with. The field is weak enough so as not to be noticeable in bulk, but obvious in the chips.

loose nut
12-17-2013, 11:34 PM
That sounds like a likely answer. Thanks.

boslab
12-18-2013, 01:33 AM
Magnetism is mysterious, no one has been able to satisfactorily tell me what it is yet, what it does yes how it does it yes but what is it, i wonder how big a magnetic domain in a ferrous material is? They all cancell out and are jumbled in a lump of metal, its monolithic and the sum of all the domains is zero, but when you chop it up by cutting, what then, can a bit of swarf contain a whole domain of the original bar? Or do the domains shrink to accomodate their new environment?
If a bit if swarf was a whole domain then it would be like a bar magnet.
I had noticed that in time the magnetic swarf gradually loses this property, does that mean that the domains are reforming like some weird recrystallisation ?
More questions than answers im afraid, you can magnetise a rod by hitting it on the end, same thing perhaps?
I dont understand this magnetism but thats why its fascinating.
Mark

Blackadder
12-18-2013, 03:12 AM
don't align your lathe North and South ( just joking )

if you hammer a piece of iron that is north and south it will become very weakly magnetised

I get it rarely as well, I have put it down to the stock being lifted at the stock yard with a magnet crane

just my 2 cents

Stuart

winchman
12-18-2013, 03:38 AM
So, how should I orient this while hammering on it to keep it from becoming magnetized?

http://image.made-in-china.com/4f0j00ACItKMglAhqH/Casting-Grinding-Ball.jpg

ikdor
12-18-2013, 07:10 AM
So, how should I orient this while hammering on it to keep it from becoming magnetized?

http://image.made-in-china.com/4f0j00ACItKMglAhqH/Casting-Grinding-Ball.jpg

Hammer it while it's rolling down hill...
Igor

loose nut
12-18-2013, 10:20 AM
don't align your lathe North and South ( just joking )

if you hammer a piece of iron that is north and south it will become very weakly magnetised

I get it rarely as well, I have put it down to the stock being lifted at the stock yard with a magnet crane

just my 2 cents

Stuart

I aligned it east and west for just that reason and I rarely beat on it anyway.:eek:

dian
12-18-2013, 01:17 PM
recently i bought a peice of 22 x 14 mm keystock and to my surprize its fairy magnetic. now, these are 6 m bars stocked on shelves. what might these guys have done to make it magnetic?

ahidley
12-18-2013, 02:49 PM
Banging on it will magnitize it. As will a dull endmill cutter or a vibration

JoeLee
12-18-2013, 03:05 PM
The same thing happens when you take a file to a piece of steel, sometimes the filings become magnetized and stick to the file.

JL..........................

dian
12-18-2013, 03:53 PM
glad than never happened to me yet.

JoeLee
12-18-2013, 09:22 PM
Oh, but it will one of these days.

JL...............
glad than never happened to me yet.

Don Young
12-18-2013, 10:16 PM
It is quite common for steel to become slightly magnetized from the earth's field when it stays stationary for years. Hammering speeds up the process. Cast iron is very magnetic but does not retain any significant magnetism when the magnetizing force is removed.

dian
12-19-2013, 03:39 AM
that would mean, there is no danger magnetising a mill by putting magnets on it?

Don Young
12-19-2013, 10:14 PM
I "never say 'never'' but I don't think it is possible for cast iron to become magnetized. I would appreciate hearing about anyone who has done it.


that would mean, there is no danger magnetising a mill by putting magnets on it?

darryl
12-20-2013, 12:34 AM
I can see there being a nano-scale mechanical vibration at the root of this. Perhaps in some cases an oriented vibration or a sympathetic resonance is able to effectively align molecules such that the symptom of magnetization occurs.

Toolguy
12-20-2013, 09:14 AM
The easy fix is to get one of those $30 plug in demag boxes. One swipe over that and you are demagged.

The Artful Bodger
12-20-2013, 02:18 PM
If you have expensive machines and tools that have become magnetized just send them to me where the environmental lines of flux are going the other way and they will be cured.

loose nut
12-20-2013, 07:22 PM
I'll just wait until the earths magnetic fields reverse (any day now) and save myself the shipping.