How To Choose A Magnet Grade?

Update:10-05-2021
Summary:

  After determining the best material for your magnet o […]

  After determining the best material for your magnet or magnetic component, the next step is to determine the specific material grade required for your application.

 

  For neodymium, cobalt Sa and ceramic materials, the grade is an indicator of the strength of the magnet: the higher the grade number of the material, the stronger the magnet. Alnico is the obvious exception to this rule. The size-dependent nature of Alnico means that grade is not always related to strength. Choosing the right material grade will have a profound impact on the performance of the product.

 

  1. Maximum working temperature

 

  The maximum operating temperature is the main factor in deciding which magnet material to choose. It is also important when determining the grade of the material. Magnets are very sensitive to temperature fluctuations, so it is important to define your operating temperature range before choosing a grade.

 

  2. Required magnetic field density or holding force

 

  When determining the required magnetic field density or holding force, we want to draw attention-do not choose a level higher than what you actually need. When 45 MGOe neodymium is enough, why use 52 MGOe neodymium for design? Choosing the highest strength material grade may be attractive, but it may not be used in your intended application. For example, N55 (55 MGOe neodymium) has high strength, but there is a risk of demagnetization in high temperature applications. Choosing a higher level than you need may also be unnecessarily expensive, especially if you are designing for a large number of consumer applications.

 

  Neodymium magnet tension calculator

 

  Mar Cobalt Magnetic Rally Calculator

 

  If you are designing for clamping force applications, then these calculators will allow you to adjust the parameters to determine the required slope, shape, diameter and thickness.

 

  3. Degaussing resistance

 

  When choosing a magnet grade, the last factor to consider is the demagnetization resistance. This factor can have a significant impact on your final design. Your maximum operating temperature is directly related to the intrinsic coercivity (HCI) of the material. HCI is an anti-demagnetization material. The higher the HCI, the higher your working temperature. Although heat is the main factor in degaussing, it is not the only factor. The magnetic field generated in the system and the geometry of the part are other key factors that demagnetize the resistor. Once demagnetization occurs, the damage is usually irreparable.

 

  We provide a tool to help you calculate demagnetization resistance for several variables:

 

  Demagnetization/Permeability Coefficient (Pc) Calculator

 

  Use this calculator to select potential design paths based on your magnet grade, shape (Pc) and temperature.

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