How to choose the right magnet?

How to choose the right magnet for my application? 

Neodymium magnet, rare-earth magnet, ceramic magnet, flexible magnet, strong magnet.  So many materials to choose from!

Here are a few characteristics to consider before making your next magnet purchase :

1) Selecting a magnet based on the application

How will the magnet be used? 

This is the key question that needs to be answered.  Consider what purpose your magnet will be used for.

  • Do you need your magnet to hold something in place, to lift an item or to retrieve an object?
  • Will it need to push or separate?
  • Is it intended to organize, store, hang or clear areas of debris?

Do you have a mechanical plan, a drawing or a picture that could illustrate what you intend to do with the magnet?  Feel free to contact our specialists and they will help you with your project.

 

 2) Selecting a magnet based on the size and shape

Keeping in my the application, think about the following:

  • Where will it be used?
  • Do you plan to use the magnet indoor or outdoor (or both)?
  • Are there any weight requirements?
  • What is the required shape (length, width, height or diameter)?
  • Is it a special shape?
  • What type of surface will it be applied to?
  • Do you require an adhesive on one side?
  • Will it be a direct applicaiton (magnet direct to metal)?

The properties of a magnet will differ greatly according to the size and shape.  Take into considerations whether the magnet will fit in the object in which you wish to place it. 

Knowing the answer to all of the above will prevent you from using the wrong type of magnet and will reduce the amount of options possible.

 

3) Selecting a magnet based on the type of material

The major types of magnets are:
  • Neodymium (NdFeB)
  • Samarium-Cobalt (SmCo)
  • AlNiCo (Aluminium, nickel, cobalt)
  • Ceramic (hard ferrite)
  • Flexible

They all have different physical and magnetic properties as describe in this article : Magnetic materials : Pros and Cons (link insert).

Please check the differences in properties in order to select a suitable magnet for your application.

 

4) Selecting a magnet based on the required strength?

There are different ways to calculate the strength of a magnet.  Some might refer to pull force (absorptive power) and other to mega gauss oersteds (MGOe) or gauss (also called magnetic flux density).

 

Pull force

If you define the strength of a magnet by pull force you will find useful this table (insert).  It is prepare to facilitate your decision by shape, size and pull force.  At this moment this table only gather our neodymium magnet.

We calculate the pull force when a magnet is attached to an iron plate (thicker than the magnet itself) and pulled perpedicularly in the direction of magnetization.  The property value shown is the value when the property is utilized to its maximum.  Please note: this is a reference value and not a guaranteed value.

As a rule of thumb a magnet 3/4'' diameter x 1/16'' thick will have a stronger pull force than a magnet 1/16'' x 3/4'' thick.

 

Gauss

The magnetic flux density (gauss) refers to the magnetic flux (number of lines of magnetic field) per unit area.  It can be measured with a device (gauss meter) or calculated.  There is no set standard in the magnet industry to calculate the magnetic flux density since the measuring devices, environmental conditions and calculation formulas differ according to the manufacturer.

In this application the magnet 1/16'' diameter x 3/4'' thick will have a greater magnetic flux density than the 3/4'' diameter x 1/16'' magnet.

 

5) Selecting a magnet based on operating temperature

All magnetic materials experiene a change in flux density as their temperature increases and decreases from an ambient temperature.  Most magnets will increase in strength as the temperature drops and most of them will lose some of their performance when the temperature increases. 

Make sure when selecting your magnet material that the application is not greater than the maximum operating temperature of your magnet.

 

Ask the specialist

With the above recommendations you will be able to make a decision based on the application, on the size and shape, on the right material, on the required strength and on the operating temperature.

If you are still uncertain please contact one of our magnet specialists and they will guide you througth the decision making process.

 

Other related articles :

Neodymium magnets: How are they made?

How does a permanent magnet work?

Magnet materials: Pros and Cons

What are neodymium magnets?