Magnetic vehicle signs

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Wondering what thickness you use for magnetic vehicle signs, 030" or .045" thickness?

[mb20music 760]

I think the most common is the .030

[BannerJohn 1,324]

I think the most common is the .030

Yes that is the standard and what I use...never had one blow off.

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That is what I am using.

[slice&dice 2,450]

In my opinion, a much more vital factor than the thickness is the "holding" strength of the magnetic material.

16 poles per square inch is preferable to the 14ppi that is routinely provided by many suppliers.

And of course, always make sure to round the corners.

(I use a quarter coin to provide a radius guide for cutting corners, but if you're doing a lot of them, just get a corner-radius die punch machine)

[BannerJohn 1,324]

In my opinion, a much more vital factor than the thickness is the "holding" strength of the magnetic material.

16 poles per square inch is preferable to the 14ppi that is routinely provided by many suppliers.

And of course, always make sure to round the corners.

(I use a quarter coin to provide a radius guide for cutting corners, but if you're doing a lot of them, just get a corner-radius die punch machine)

I use a corner rounder that I paid around $4 for at a craft store...it works great and is very fast. Perfect rounded corners every time.

AS for magnets...I wouldn't use anything but Magnum brand. I've tried the other stuff. I don't know about the ppi..according to this chart, it looks like the less,the better. But I could be reading it wrong.

[tshirtn00b 12]

+1 for the craft store deal of the day. I got one for $9 and love it.

[stetson5331 80]

Thats the trick is rounded corners for sure..DEFINITLY helps it from blowing off..+1 on the magnum..ALL I use...

[slice&dice 2,450]

All right, now you've got me looking up the details of magnetic forces.

This is what I came up with --

Br max (Residual Induction) - Also called "Residual Flux Density". It is the magnetic induction remaining in a saturated magnetic material after the magnetizing field has been removed. This is the point at which the hysteresis loop crosses the B axis at zero magnetizing force, and represents the maximum flux output from the given magnet material.

Then, there's Gauss and Gilbert.

And also Oersteds & Webers.

Oy vey.

http://www.kjmagnetics.com/glossary.asp

All I know is that a roll of 24" magnetic material is really HEAVY.

[BannerJohn 1,324]

All right, now you've got me looking up the details of magnetic forces. This is what I came up with -- Br max (Residual Induction) - Also called "Residual Flux Density". It is the magnetic induction remaining in a saturated magnetic material after the magnetizing field has been removed. This is the point at which the hysteresis loop crosses the B axis at zero magnetizing force, and represents the maximum flux output from the given magnet material. Then, there's Gauss and Gilbert. And also Oersteds & Webers. Oy vey. http://www.kjmagnetics.com/glossary.asp All I know is that a roll of 24" magnetic material is really HEAVY.

I too did some research and the only thig I could find that I actually understood was that the thicker the magnet,the lower the ppi.

[OWJones 1,981]

With regards to the P.P.I. measurements, check out the pictures on this site http://www.wondermagnet.com/viewingfilm.html and scroll down to the bottom. The 2nd picture up from the bottom shows magnetic viewing film placed on the back of a flexible refrigerator magnet - basically a thinner version of the material that magnetic signs are made from.

The alternating light and dark strips display the alternating north/south poles in the magnetic material. As the thickness of the material decreases, the distance between the poles (and thus the P.P.I. number) needs to increase to maintain attraction to the ferrous material (i.e., metal). Really thin material, like the refrigerator magnet in this picture has a fairly high P.P.I. value.

As you increase the thickness of the material, the magnetic strength (measured in Gauss) increases and the alternating poles can be moved further and further apart without losing any attraction.

Bottom line, the P.P.I. value is not directly related to the strength of the magnets. The only accurate measurements of magnetic strength are gauss or pounds of pull (kind of like wattage of a light bulb vs. lumens - they are related and bigger means better/brighter - but two totally different numbers).

BTW - if you order any of the big magnets off of that site, be extremely careful - not only are they strong enough to crush a finger (see here http://www.wondermagnet.com/crush.html) but they are brittle metal ceramics and if dropped or allowed to slam together, they can shatter like glass and send dangerously sharp shards flying in all directions. As long as you're careful, though, they are awesome!

Signed,

Certifiable magnet geek

[fatewilleatyou 3]

I made some shaped .30 magnets. Scoring the vinyl layer and breaking off the rest worked fine. The thing I'm worried about is blow off if I sell them as car usable. The edges are all rounded merged letter outlines. The magnet ares is only 5.5" x 4", anyone know if that's enough surface to stay put on a car? I don't drive, so I can't test it.