Hi
I want to use a magnet to hold a piece of ferrous metal about 3/16ths" thick up against another piece of metal that is about 3/4ths to 1" thick. The magnet has to be about the diameter of a dime, or maybe a nickle. I guess a penny’s diameter would work.
Any suggestions?
TYVM
Be very careful. Magnets this strong have the potential to crush flesh and break bones.
EDIT: The 3/4" to 1" metal is actually aluminum. The magnet needs to be up against the aluminum. I wonder what strength magnet I would need to have the magnet pull enough on the ferrous metal through the non-ferrous metal to hold it in place reasonably enough so that it doesn’t move more than small amount…maybe 1/16" this way or that.
I need to know what strength though. Is N52 too much?
The answer depends on the load you’re trying to carry. If it’s in any way significant, I’d say you need a different way to carry it. You’re not going to pull much magnetism through an inch of aluminum with even the strongest of magnets.
I think the plate weighs 8oz or so. I will check when I go to work Monday. It’s the scatter plate between a transmission and engine block. Keeping that thing on the back of the engine block is a real pain even with it on the dowels. I thought a strong magnet would keep it from falling off the dowels while gettin the torque convertor studs with the flyweel holes.
I don’t know what a scatter plate is but if this is just going to be used for assembling something and that’s it and on a regular basis (say, more then once a day) you’ll have to be really careful with neodymium magnets. They’ll pull right out of your hand and they have a bad habit of shattering on impact. You might want to look into rubber coated neodymium magnets for this application but you’ll have to take into consideration that they’ll probably have to be stronger/bigger because the magnet itself will be that much further away from the project.
KJMagnetics has a pretty wide selection with good descriptions of how much weight each one can hold. You might want to peruse their wares.
Maybe something like this.
ETA, come to think of it, a rubber coated magnet is also going to be a lot easier to remove afterwords when your hands are covered in grease.
Agreed with above, and I think an electro-magnet would work better for the same reasons in that post. 8oz. is not much weight, but rare earth magnets are kind of frightening for the collateral damage they can cause.
Why are you focusing on magnets as a fastener? Why not bolts or staps or other conventional means?
This is going to be in a vehicle? As in, something that goes over rough roads and bumps and sometimes potholes? I don’t think any permanent magnet is going to be able to hold on through an inch of aluminum in those conditions, and an electromagnet would probably be considerably more trouble than it’s worth.
Like I said above, I have no idea what a scatter plate is, but I was under the impression that it goes somewhere in the drive train and it’s just sort of propped on some dowels while the next part is put in place. I’m assuming the next piece is heavy and unwieldy and is hard to line up and has a habit of knocking the scatter plate off the dowels requiring the mechanic to set the part down, put the scatter plate on and start over. My guess is that the magnet is just to keep said scatter plate in place while the next part is installed, then the magnet would be removed and used on the next assembly.
Another option that may or may not work is a ‘dollop’ of heavy grease (something like axle or wheel bearing) behind the scatter plate to sort of glue it in place. At least this way it’s harder to knock off the dowels. Of course this might not be applicable.
Can you use Alnico instead of aluminum?
JoeyP has it pretty much spot-on.
I actually work in a lab where we develop/test prototype engines and transmissions. They are not in a vehicle, but are setting on a system of steel recievers situated on a thick bedplate of solid steel. In fact its like this:
The bottom-most picture shows a FWD automatic transmission hooked up to dynamometers via jack shafts. I sometimes have to do torque convertor changes, so off comes the trans, out comes the torque convertor and put it all back together.
The convertor has 4 studs on it that must line up with the holes of the engines fly-wheel. A very tedious job at times by itself, but throw in a part that refuses to stay put amd its extremely frustrating to say the least. As JoeyP stated the scatter plate falls off repeatedly. I did try some silicon goop but it didn’t work too well. Maybe I will try some axle grease…I just thought magnets would be really slick…because nothing can get between the transmission and scatter-plate mating surfaces. Hence I thought a strong magnet on the one side of the aluminum engine block would be a cool way to beat this problem.
If it makes any difference to you, I just did a little test. I grabbed (because it was nearby) a 9/16" socket that’s 2.5 inches long and stuck a 1/2 cube (with a hole in the center like this to the end of it. It did not stick to my fridge. When I put two of them on the end, it did stick to my fridge. I also have a 1" sphere neodymium magnet that also held the socket to my fridge. Now, KJMagnetics doesn’t have any way for me to pull up my old order so I’m not sure which strength magnets I have but it’s safe to say I probably have the N52 I was pretty excited when I found that website and probably ordered the strongest ones I could find. But like I said before, you might look into getting the rubber coated ones both so they don’t shatter and so you can get a grip on them. If your hands are greasy, you won’t stand a chance against the polished surface.
Also, you said it can only be the diameter of a dime, but how long can it be?
Something like this would fit and actually probably be overkill. Since you likely wouldn’t be able to pull it off by yourself. But the strongest cylindrical one I could find only required about 40# of force to remove. That might even be too strong. Luckily, they’re not very expensive so you could order a bunch and experiment. Besides, if you’re doing this multiple times per day, you’re likely to break them at some point anyways.
There won’t be a problem if the steel parts become somewhat magnetized, will there?
Nope the plate getting slightly magnetized shouldn’t matter. Thanks for the help everyone. I know where I can get some hard drive magnets at work. I will try them first and see what happens.
Off topic comment: Joey P, I went to your link and found this MONSTER magnet! $1,200 worth of pure awesome.
I can tell you that if you want to pull things together a magnet is capable but it is problematic if you require location accuracy. The magnetic field is not a point so accuracy is unreliable. If it is a round magnet, it will pull somewhere on a circular pattern.
http://www.google.com/search?q=magnets+magnetic+field&hl=en&rlz=1C1CHFX_enUS443US443&nord=1&biw=1600&bih=799&site=webhp&prmd=imvns&tbm=isch&tbo=u&source=univ&sa=X&ei=8oR_TpXBJ8XksQKE5qwI&ved=0CFYQsAQ This is what magnetic fields look like.