Classification and Characteristics of Nd-Fe-B Magnets
Nd-Fe-B magnets can be divided into bonded Nd-Fe-B magnets and sintered Nd-Fe-B magnets.
Bonding is actually injection moulding, while sintering is formed by vacuum and high temperature heating!
Nd-Fe-B magnet is the permanent magnet with the strongest magnetic force up to now. The material is N35-N52; various shapes can be processed according to specific requirements: round, square, punching, magnetic tile, magnetic rod, convex, trapezoidal, etc. Despite these advantages, the surface is easy to rust, so some protective surface treatments are usually needed: nickel plating, zinc plating, gold plating, epoxy resin plating, etc. The applicable ambient temperature of ordinary NdFeB magnets is below 80 degrees, but there are also several kinds of NdFeB magnets that can withstand 200 degrees. Mainly used in electronics, electrical appliances, packaging, motors, toys, leather, automotive machinery and so on.
Major Materials for Production of Nd-Fe-B Magnets
The main materials for producing Nd-Fe-B magnets are rare earth metal neodymium, rare earth metal praseodymium, pure iron, aluminium, ferroboron alloy and other rare earth raw materials.
Production Technology of Nd-Fe-B Magnets
The production process of Nd-Fe-B magnet is as follows: mix the materials and melt them, then crush the metals into small particles. Put the small particles into the mould and press them into shape. Then sinter. The sintered one is the blank. The shape is usually square or cylindrical. Take the square as an example, the size is generally concentrated in the length and width of 2 inches, the thickness is about 1-1.5 inches, the thickness is the direction of magnetization (high-performance magnets are oriented, so there is direction of magnetization). Then, according to the actual needs, the blank is cut into the required size and shape. Cut the magnet, chamfer, after cleaning, electroplating, magnetizing, you can.
Processing technology of Nd-Fe-B:
There are basically two kinds: slicing machine or wire cutting.
The slicer is a diamond inner hole cutting blade with thickness of about 0.3mm. The magnet is cut into the required size according to the requirements. But this method is only suitable for simple square and cylindrical shapes. Because of the inner hole cutting, the size of the magnet can not be too large, otherwise it can not be placed in the blade.
Another method is WEDM. Usually used to cut tiles, and large-scale products.
Perforation: Small holes are usually drilled with vibrating diamond grinding wheel bits. Large holes, the use of sleeve holes, which can save material costs.
Dimensional accuracy of Nd-Fe-B products
The dimension accuracy of Nd-Fe-B products is about (+/-) 0.05 mm, which is more economical. In fact, the existing processing methods can completely achieve the accuracy of (+/-) 0.01. However, NdFeB usually needs to be coated by electroplating, so it needs to be cleaned before electroplating. The corrosion resistance of this material is very poor, and the dimensional accuracy will be cleaned out during the pickling process. Therefore, the real plating products, the accuracy can not reach the level of pure cutting and grinding processing.
Orientation of NdFeB
Orientation: NdFeB is a oriented magnet. Simply put, the actual effect is that a square magnet, only the direction of orientation magnetic field intensity is the largest, and the other two directions, magnetic field intensity is much smaller. When you suck several magnets together, the oriented magnets can only be sucked in one direction, and can not be sucked together arbitrarily. The work of this orientation is carried out when blanks are pressed. This also limits the size of the magnet blank, especially the height of the direction of magnetization (generally the direction of the NS pole). At present, the reasonable height size of magnetizing direction is generally not more than 35 mm. High performance, generally not more than 30 mm. So what if you need a magnet with a large size in the direction of magnetization? Several magnets can be superimposed. This effect is similar to the series connection in an electric field. Of course, this method is of little significance in practical use and seldom used.
Where can I buy NdFeB magnets?
In fact, it is very easy to find Nd-Fe-B manufacturers, smaller ones, and then say what products you want to make, the number is thousands or tens of thousands of a month, buy a few samples to test the performance. If you put it in place, and the product is relatively ordinary, you can basically get free samples. Or it's not expensive. Big manufacturers, don't look for, people basically ignore you.
You are welcome to add what you think is wrong or missing in the commentary, so that the next reader will learn more, and you know what you need...