Some customers ask whether the magnet coating will affect its magnetism from time to time? How big is the impact? Let's talk about this topic today.
This is indeed an important factor to be considered. Although the distance of one or two millimeters between the magnet and another object does not seem to be much, each distance will reduce the overall efficiency of the magnet. In some applications, even a small distance is enough to make the original sound magnet completely useless.
Most magnets need coating because they are easy to corrode (such as neodymium magnets) and they are very brittle (such as neodymium, ferrite and samarium cobalt magnets). The coating gives the magnet additional durability, but the additional durability comes at a price.
As we said, any distance between the actual magnet and the object in front of it will reduce the strength of the magnet. This is especially true in applications where rubber or plastics are more suitable than metal coatings. Although nickel (or other metal) coatings actually help to transfer magnetic fields, rubber and plastics will not. On the contrary, they will maintain a certain distance between the magnetic field and the object being acted on.
Determine how much strength is lost?
To calculate how much strength is lost, you can use the inverse square law, which states that the force of the magnet is inversely proportional to the square of the distance from the source. Generally speaking, even in a short distance, the force of the magnet will decrease rapidly.
In an internal study, we measured the force of the magnet at 1 mm, and then measured it again at 2 mm. We found that this small increase in distance reduced the strength of the magnet by four times.
This is another way of thinking: when you touch the surface of the magnet, you will receive 100% of its force, but from only two inches away, the strength of the magnet will drop to 10%. Obviously, proximity is crucial.
What should we pay attention to in magnet coating?
When retention strength is a factor, it is best to use a metal based coating, such as nickel. However, larger magnets require multiple layers of coatings for physical protection, sometimes with a nickel layer inside, then a copper layer, and then another nickel layer outside. Because there are many layers at a distance from the magnet, the overall strength will be reduced.
If you need waterproof, non slip or color coating, it is best to use plastic or rubber. Of course, the problem is the constant distance between the magnet and the surrounding object. If you need to use a plastic or rubber coating, you may need to use a larger magnet than usual to make up for the lost strength.
Magnets without coating;
Sintered permanent ferrite magnet
More about the magnet coating article introduction;
Neodymium magnet coating and plating [ type color thickness ]
This product is a high-performance 8-pole ring magnet with radial magnetization. The material is ferrite. It belongs to a ferrite multi-pole magnetized ring. The outer diameter of the magnet is 75mm, the inner diameter is 51mm, and the height is 35mm....
The sample is M10 countersunk hole square NdFeB magnet, the length and width are 75mm, thickness is 25mm, with strong magnetic strength, specializing in heavy industry, machinery and equipment, salvage, etc., welcome to bring quantities to consult the price....
Sample display is a N52 grade ultra-thin rectangular block neodymium magnet, length size 8mm, width 1.8mm, thickness is only 0.6mm, can be affixed with adhesive backing, scribing marking, although the size is small, but still has a certain degree of magnetism, suitable for use in a number of precision instruments, meters, handicrafts, toys....
This is ring-shaped neodymium magnet with an outer diameter of 4mm, a thickness of 4mm, and a middle hole of 1.6mm. It is N48 grade, with a surface magnetic force of about 3900 Gauss. It is produced and photographed by the courage magnet manufacturer carrich. If you are interested in this product, please leave us a message or send us an email....
Buy small hole radial magnet ring, high precision radial cylindrical magnet with small hole, welcome to contact Courageous Magnet Manufacturer, we have many customized cases, such as the one you see now, belongs to the motor radial magnet, outer diameter 2.5mm, center hole 1mm, height 4.8mm, N48H grade...
This product is a rectangular pot magnet with a hole, usually a counterbore. It is used together with screws. There are one with one counterbore and two with two counterbore holes. It is suitable for fishing, lifting metal objects, kitchen and bathroom hooks, etc., rectangular Can magnet specifications are customized according to customer requirements. Please contact us for prices....
Our company is a manufacturer of permanent magnets for electric motors, we can provide you with multi-pole ring magnets made of various materials, you are now browsing this is an injection molded ferrite ring, OD 41mm, hole 35mm, height 24.5mm, radial 4-polar magnetization, surface magnetic strength of 750 gauss or so, there are molds and samples, welcome to inquire about the price....
This is a customized ceramic ferrite pot magnet for customers, which consists of galvanized iron shell + ring ferrite magnet, the size of the iron shell, the size of the magnetic ring and so on can be processed and customized according to your actual needs....