Super Magnet: Magnets Supplier Singapore
Note : Credits for the FAQ section below to K&J Magnetics, Inc
After perusing the frequently asked questions to satisfy some of your common queries, if you are ready to buy some raw magnet material of your desired shape, please contact Super Magnet or click here.
Super Magnets in General
There are several simple methods that can be used to identify the (Scientific) North and South poles of neodymium magnets.
1)The easiest way is to use another magnet that is already marked. The North pole of the marked magnet will be attracted to the South pole of the unmarked magnet.
2)If you take an even number of magnets and pinch a string in the middle of the stack and dangle the magnets so they can freely rotate on the string, the North pole of the magnets will eventually settle pointing North. This actually contradicts the “opposites attract” rule of magnetism, but the naming convention of the poles is a carry over from the old days when the poles were called the “North-seeking” and “South-seeking” poles. These were shortened over time to the “North” and “South” poles that we know them as.
3)If you have a compass handy, the end of the needle that normally points North will be attracted to the North pole of the neodymium magnet.
4)Use Pole Identifier Devices.
(Please note: In some magnetic therapy applications, the definitions of the poles are reversed from the scientific definition described above. Please be sure to confirm the proper definition of the poles prior to using magnets for medical purposes)
No, both poles are equally strong.
Neodymium (more precisely Neodymium-Iron-Boron) magnets are the strongest permanent magnets in the world.
We use the description “Magnetized thru thickness” to identify the locations of the poles on our block magnets. The thickness is always the last dimension listed for block magnets. If you take one of our block magnets and place it on a flat surface with the thickness dimension as the vertical dimension, the poles will be on the top and bottom of the magnet as it sits.For example: On one of our blocks of 1″ x 1/2″ x 1/8″ thick (25.4 x 12.7 x 3.17mm). If you place one of the blocks so it is on a flat surface with 1/8″ (3.17mm) as the vertical dimension, the poles will be on the top and bottom as the magnet sits. This means the poles are located in the middle of the 1″ x 1/2″ sides (25.4 x 12.7mm).
Ferromagnetic materials are strongly attracted by a magnetic force. The elements iron (Fe), nickel (Ni), and cobalt (Co) are the most commonly available elements. Steel is ferromagnetic because it is an alloy of iron and other metals.
Magnetic fields cannot be blocked, only redirected. The only materials that will redirect magnetic fields are materials that are ferromagnetic (attracted to magnets), such as iron, steel (which contains iron), cobalt, and nickel. The degree of redirection is proportional to the permeability of the material. The most efficient shielding material is the 80 Nickel family, followed by the 50 Nickel family.
No, we don’t, nor can anyone else, becuase they don’t exist. All magnets must have at least two poles.
Disc, cylinder, and sphere shapes definitely cannot be manufactured this way. Rings magnetized this way are referred to as “radially magnetized”, but it is not currently possible to manufacture neodymium ring magnets this way. We are working on it, however.
Yes, two or more magnets stacked together will behave exactly like a single magnet of the combined size. For example, if you stacked two of our 1/2″ x 1/8″ (12.7 x 3.17mm) disc magnets to form a 1/2″ x 1/4″ (12.7 x 6.35mm) combined size, the two magnets would have the same strength and behave identically to the discs which are 1/2″ diameter x 1/4″ thick (12.7 x 6.35mm).
All of the pull force values we specify have been tested in our laboratory. We test these magnets in two different configurations. Case 1 is the maximum pull force generated between a single magnet and a thick, ground, flat steel plate. Case 2 is the maximum pull force generated with a single magnet sandwiched between two thick, ground, flat steel plates. Case 3 is the maximum pull force generated on a magnet attracted to another magnet of the same type. The values are an average value for five samples of each magnet. A digital force gauge records the tensile force on the magnet. The plates are pulled apart until the magnet disconnects from one of the plates. The peak value is recorded as the “pull force”. If using steel that is thinner, coated, or has an uneven or rusty surface, the effective pull force may be different than recorded in our lab.
Most other online calculators are based on theoretical formulas, which are notoriously inaccurate, especially for very large or very small sizes. Our fanatical engineers have worked long and hard in the laboratory developing our calculation method that are VERY accurate based on thousands of test cases. ten samples of each magnet. A digital force gauge records the tensile force on the magnet. The plates are pulled apart until the magnet disconnects from one of the plates. The peak value is recorded as the “pull force”. If using steel that is thinner, coated, or has an uneven or rusty surface, the effective pull force may be different than recorded in our lab.
Because pull force values are tested under laboratory conditions, you probably won’t achieve the same holding force under real world conditions. The effective pull force is reduced by uneven contact with the metal surface, pulling in a direction that is not perpendicular to the steel, attaching to metal that is thinner than ideal, surface coatings, and other factors.
Yes, we supply Demagnetization Curves for Neodymium magnet upon customers’ request.
The traditional way of visualizing magnetic fields is to place a magnet near a surface covered with iron filings. If you already have some of our magnets, this is a good experiment to conduct!
Gaussmeters are used to measure the magnetic field density at the surface of the magnet. This is referred to as the surface field and is measured in Gauss (or Tesla). Pull Force Testers are used to test the holding force of a magnet that is in contact with a flat steel plate. Pull forces are measured in pounds (or kilograms).
There is a direct relationship between the Flux Density of the magnetic material and the Pull Force per square inch (or ‘cm’ or ‘mm’) of the magnets that are used. The Pull Force number takes into account the size and shape of the magnet along with the flux rating of the material from which it is made.
The formula for finding the Pull Force of a cube or bar magnet is as follows:
Pull Force = 0.576 x Br² x (Th) x √‾A where
Br = Remanence or Flux Rating in KiloGauss.
Th = Thickness of Magnetized Surfaces in inches
A = Surface Area (L x W) in inches
A Grade 8 Ceramic Magnet (3,900 Gauss material) that is 4 Inch Long, 1 Inch Wide, and 1 Inch Thick will have a Pull Force as follows:
Pull Force = 0.576 x Br² x (Th) x √‾A
= 0.576 x (3.9)² x (1) x √‾4
= 0.576 x 15.21 x 1 x 2
Pull Force = 17.52 Pounds
That translates into 4.38 Pounds of Pull Force per Square Inch (17.52 lb. ÷ 4″)
A N42 Grade Neodymium Magnet that is 2″ Long, 1 Inch Wide and .5 Inches Thick will have a Pull Force as follows:
Pull Force = 0.576 x Br² x (Th) x √‾A
= 0.576 x (13.2)² x (.5) x √‾2
= 0.576 x 174.24 x .5 x 1.414
Pull Force = 70.96 Pounds
That translates into 35.48 Pounds of Pull Force per Square Inch (70.96 lb. ÷ 2″).
So this Neodymium magnet that is half as long and half as thick as the large Ceramic Magnet has a Pull Force per square inch that is 8.1 times higher than the larger Ceramic magnet.
On Neo or Neodymium Magnets
Neodymium magnets are a member of the rare earth magnet family. They are called “rare earth” because neodymium is a member of the “rare earth” elements on the periodic table. Neodymium magnets are the strongest of the rare earth magnets and are the strongest permanent magnets in the world.
Neodymium magnets are actually composed of neodymium, iron and boron (they are also referred to as NIB or NdFeB magnets). The powdered mixture is pressed under great pressure into molds. The material is then sintered (heated under a vacuum), cooled, and then ground or sliced into the desired shape. Coatings are then applied if required. Finally, the blank magnets are magnetized by exposing them to a very powerful magnetic field in excess of 30 KOe.
You definitely cannot solder or weld to neodymium magnets. The heat will demagnetize the magnet and could cause it to catch fire posing a safety risk.
so they often use the Residual Flux Density (BrMax) of the material, which really doesn’t specify much about the actual magnet. This value is essentially the magnetic field density inside the magnet material. Since you will never be inside the magnet, or using the field inside the magnet, this value doesn’t really have any practical use. The surface field of a magnet is a much more accurate specification for a magnet. The surface field is exactly what it sounds like. It is the magnetic field density at the surface of the magnet as measured by a Gaussmeter. This value is tested and specified for each of our stock magnets.
No, neodymium magnets do not require a keeper for storage like Alnico magnets
Very little. Neodymium magnets are the strongest and most permanent magnets known to man. If they are not overheated or physically damaged, neodymium magnets will lose less than 1% of their strength over 10 years – not enough for you to notice unless you have very sensitive measuring equipment. They won’t even lose their strength if they are held in repelling or attracting positions with other magnets over long periods of time.
In most applications, the answer is simply “no”. If the magnets will be exposed to higher temperatures while in repelling applications, the answer is “possibly”. The exact answer is a bit too complicated for a FAQ answer, and requires specifics about the application.
Just about anything you can imagine!
From a dictionary : [ne”odim’eum] The only real trick to pronouncing it correctly is to treat the ‘y’ as an ‘i’. It is pronounced as if it were spelled “neodimium”.
Yes, our magnets are fully RoHS compliant, meeting the European Parliament Directive entitled “Restrictions on the use Of Hazardous Substances” (RoHS). This Directive prohibits the use of the following elements in electrical/electronic equipment sold after 7/1/2006: cadmium (Cd), lead (Pb), mercury (Hg), hexavalent chromium (Cr(VI)), polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs).
No, once a magnet is fully magnetized (saturated), it cannot be made any stronger.
Here are the dimensions of these coins along with the closest matching magnet that we currently stock:
US Penny = 0.75″ dia. x 0.061″ (19.05 x 1.55mm) disc magnet
US Nickel = 0.84″ dia. x 0.077″ (2.13 x 0.19mm) disc magnet
US Dime = 0.71″ dia. x 0.053″ (1.80 x 0.13mm) disc magnet
US Quarter = 0.95″ dia. x 0.069″ (2.41 x 0.17mm) disc magnet
US Half Dollar = 1.21″ dia. x 0.085″ (3.07 x 0.21mm) disc magnet
The maximum operating temperature is the maximum temperature the magnet may be continuously subjected to with no significant loss of magnetic strength. This is 176ºF (80ºC) for standard grades of neodymium magnets. The Curie Temperature is the temperature at which the magnet will become completely demagnetized. This is 590ºF (310ºC) for standard grades of neodymium magnets. Higher temperature grades have higher maximum operating temperatures and higher Curie Temperatures. At temperatures between these two points, a magnet will permanently lose a portion of its magnetic strength. The loss will be greater the closer to the Curie Temperature it is heated.
The Neodymium Iron Boron material is very hard and brittle, so machining is difficult at best. The hardness of the material is RC46 on the Rockwell “C” scale, which is harder than commercially available drills and tooling, so these tools will heat up and become damaged if used on NdFeB material. Diamond tooling, EDM (Electrostatic Discharge Machines), and abrasives are the preferred methods for shaping neodymium magnet material. Machining of neodymium magnets should only be done by experienced machinists familiar with the risk and safety issues involved. The heat generated during machining can demagnetize the magnet and could cause it to catch fire posing a safety risk. The dry powder produced while machining is also very flammable and great care must be taken to avoid combustion of this material.
The grade, or “N rating” of the magnet refers to the Maximum Energy Product of the material that the magnet is made from. It refers to the maximum strength that the material can be magnetized to. The grade of neodymium magnets is generally measured in units millions of Gauss Oersted (MGOe). A magnet of grade N42 has a Maximum Energy Product of 42 MGOe. Generally speaking, the higher the grade, the stronger the magnet.
As a general rule of thumb, a peak field of between 2 and 2.5 times the intrinsic coercivity is required to fully saturate a magnet. For standard neodymium magnets, the field required is minimum of 24 KOe, but 30 KOe is usually the minimum used.
Yes. Neodymium Iron Boron magnets are sensitive to heat. If a magnet heated above its maximum operating temperature (176°F (80°C) for standard N grades) the magnet will permanently lose a fraction of its magnetic strength. If they are heated above their Curie temperature (590°F (310°C) for standard N grades), they will lose all of their magnetic properties. Different grades of neodymium possess different maximum operating and Curie temperatures.
On Handling Magnets
Small and medium-sized magnets can usually be separated by hand by sliding the end magnet off of the stack. Medium-large magnets can often be separated by using the edge of a table or countertop. Place the magnets a table top with one of the magnets hanging over the edge. Then, using your body weight, hold the magnet(s) on the table and push down on the magnet hanging over the edge. With a little work and practice, you should be able to slide the magnets apart. Just be careful that they don’t snap back together once they become separated. For very large magnets (generally 2″ and larger), we use a specially made magnet separating tool.
Using adhesive tape to capture the metal dust is the best way to clean magnets.
According to the United States Department of Transportation and the Office of Hazardous Materials Safety, the limit for shipping magnets by air is a magnetic field strength of 0.00525 Gauss measured at 15 feet (4.5 meters) from any point on the outside of the package. There are no restrictions on the shipping of magnetized materials by ground. When in doubt, ship magnets by ground transportation.
Neodymium magnets are composed mainly of Neodymium, Iron, and Boron. If neodymium magnets are not plated, the iron in the material will oxidize very easily if exposed to moisture. Even normal humidity will rust the iron over time. To protect the iron from exposure to moisture, most neodymium magnets are plated or coated.