How are magnets made?

There are 6 basic steps to making a magnet, such as a Neodymium Iron Boron magnet = Nd2Fe14B or Nd15Fe77B8.

1.  Make an alloy of iron, boron and neodymium.  You will need about 0.014 pounds of boron and 0.369 pounds of neodymium for every pound of iron to make an alloy of Nd2Fe14B.  This will have to be heated above 1538 degrees Centigrade to make it melt.  The mixing of the materials with the iron is very important, just like thoroughly mixing the ingredients for a cake.

2.  Grind the alloy into a powder.  After the alloy has cooled, you will need to grind it or mill it into a very fine powder.

3.  Compress the powder into a shape.  Since the magnet will have a specific shape when you are done, you use a mold of that shape to make the magnet.  For example, you may want a disk.  Pour the powder into a mold that has a disk shape, but is also deeper than the thickness of the final part.  Next, you will compress the powder with hundreds of pounds of pressure to compact the powder into a solid disk.  Heat is often used to help fuse the particles together, and is called a sintered magnet.  Sometimes a glue is used to help keep it all together, and is considered to be a bonded magnet.  To achieve precise final dimensions, you may need to grind the part.

4.  Coat the magnet.  In order to improve the corrosion resistance of the magnet, the disk needs to be plated with a thin film of nickel.  Sometimes a film of gold is used, or zinc, or an epoxy coating..  Nickel does not oxidize like iron, so it works great for magnets you will be touching.

5.  Magnetize the magnet.  All this time, the powder and the disk is not magnetized.  It would be attracted to and stick to a magnet, but it would not be able to pick up a paper clip all by itself.  So, it would be placed into a magnetizing fixture that has a coil of wire through which a very large pulse of current is passed for a very short period of time.  The magnet has to be held in place so it doesn't shoot out and hit something or someone.  It takes about a thousandth of a second to actually  magnetize the magnet. 

6.  Pack and ship it.  You now have a magnet for whatever you need.  Engineers often require special shapes or specific magnetization configurations to make the product they are designing work properly.  They talk with the magnet manufacturer and they determine how to best make the magnet that is needed.  That's why there are so many different shapes and sizes of magnets in the catalogs.

What does the inside of a magnet look like?

That's a great question!  I have a donut or ring magnet that broke when it was dropped.  I tried to glue it together with superglue, but I didn't put all of the pieces together at the same time, and now I can not fit the last piece in.  (A broken bar magnet is easy to stick together while the glue is drying.  Ring magnets don't want to stay together.  Can you figure out why?  Look at the field diagrams in the gallery.)  So, now you can see what the inside looks like in the picture.  The outside has a white epoxy coating.  The inside is a simple dark gray or medium gray color, depending on what material it is made of.  This was a ferrite magnet, so it is a dark gray color.  By the way, the brownish circle on the magnet near my fingers is a felt pad I used to help prevent the magnet from crashing into another one.  It didn't help much, did it?  If the magnet isn't painted or coated, the inside looks just like the outside.

Magnetization configurations 

How the magnet is magnetized is as important as its shape.  For example, a ring magnet can be magnetized where N is on the inside and S on the outside, or N is on one edge and S on the opposite edge, or N is on the top side and S on the bottom side, or multiple N and S poles all around the outside edge, etc.   A big help in visualizing how a magnet may be magnetized is by using a magnetic viewing film.  Obtain one of these viewing cards, and look at the magnets you have around your house.  The white line marks the boundary between the N and S poles.  Make a sketch of what each magnet looks like under the viewing film.  You will be surprised by some.