We need to pay special attention when we purchase NdFeB arc magnets or round magnets, because they are very special and there are too many factors to be determined.


To put it simply, the arc magnet must be a customized product. If there is no result, the magnet factory will produce it in advance and wait for the customer to purchase it. If you are not careful, it is easy to fall into the trap, wasting time and money. Today, the magnet editor mainly takes you to understand what factors need to be paid attention to when purchasing neodymium arc magnets.


Adequate preparation time

If you want to buy curved motor magnets, you should start preparing as soon as possible. Because you need a sample before placing an order. Normally, it takes 14 to 18 days for the factory to produce samples. If you want high-grade magnets, the factory needs to check whether there are ready-made raw materials in the market. Then the factory will send the samples to you, it will take an extra 2-3 days. You need 1-2 days to check the quality. It takes 16-22 days to wait for real mass production.


The premise of all the above calculations is that the product fully meets its own requirements without any problems. If the sample test fails, then the overall mass production time will be extended. So, we need to reserve enough time.


Drawings are very important

If you want to save time and speed up the entire process, the most important thing is the drawing. The following information needs to be marked on the drawing: arc, arc length, height, width, thickness inner diameter, outer diameter, coating, grade, tolerance.


For example, the drawing above, it will display all the information: Radian: 55 degrees,

Length: 27mm (magnet units are generally MM, millimeters, not centimeters)

Height: 6mm Width: 3±0.05

Thickness: 2.2±0.05

Inner diameter: 26.2mm

Outer diameter: 29.2mm

Plating: Nickel

N50M grade (indicates that the magnet will work normally when the temperature is below 100 degrees Celsius. If you are not sure what grade you need, you can tell the factory the working temperature range.)

1. Tolerance

    As you can see, the width is 3±0.05mm and the thickness is 2.2±0.05mm. But what does "±" mean?

That's a sign of tolerance. So, if the width is 3.05mm or 2.95mm both are acceptable. If your product is high tech, your tolerances must be even tighter. And in this industry, tolerance tolerances are different. Different shapes, different tolerances. Like round magnets, the standard tolerance is ±0.05mm, while square magnets have a length and width of ±0.1mm and a thickness of ±0.05mm. If you have special requirements, the circular tolerance can be 0.02mm, the square, the length and width can be ±0.05mm, and the thickness can be ±0.03mm. Many factory tolerances can be ±0.01mm. But the tighter the tolerance, the higher the cost. For most people, standard tolerances will meet their requirements.


2. Temperature

Regarding the drawing, as we can see, the temperature is not written. But we all know that if the operating temperature is below 100 degrees, the magnet can work normally. Because the grade is N50M. M means the magnet works well if the temperature is 100 degrees Celsius or less. For the relationship between temperature and grade, you can check the table below.


* Indicates a number, such as N*M, which can be N35M, N38M, N40M, N42M, N45M, N48M, N50M, N52M.


3. Number of S and N poles

This seems like a very simple problem. But unfortunately, it's easy to make mistakes. Most of the time, this happens when one of them (seller and buyer) is a newbie. Magnets are used in rotor devices. The number of magnets should be plural. Like 12, 24, 26. Because the same magnetic field will always push away things with similar magnetic fields. And these two different magnetic fields attract each other.


So, if you tell the seller the quantity, you should make sure they understand what you mean.

For example, if we want 2400 magnets, this is a draft. (You just sent the seller picture A) We rotate the device with magnets". So, you mean you want 2400 magnets and they are all A magnets and no B magnets? Or do you mean you want 2400 sets of magnets? 2400 pcs of A magnets, 2400 pcs of B magnets? If sellers and buyers, they are both new to this industry. 2400pcs will produce magnet A. But without 2400 pcs of B magnets, the 2400 pcs of A magnets are worthless.


4. Magnetization direction

Magnetization direction is a very important factor. Magnets are also worthless if you get them wrong. However, since the arc is a special shape, there are four magnetization directions: diameter direction, width direction, and thickness direction.


Different directions of magnetization make different directions have greater power. So, we should pay attention to this.





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