The manufacturing process of high-performance NdFeb magnet which produced by Xinfeng Magnet is mainly includes: Xinfeng magnet high-performance Ndfeb magnet manufacturing process mainly includes: raw material pretreatment and batching, vacuum melting and strip casting, hydrogen crushing and fine grinding (air mill) powder making, powder forming and isostatic pressing, blank sintering and aging treatment, magnet machining and other seven processes.
(1) Raw material pretreatment and batching: in order to remove the iron oxide on the surface of pure iron, cut the pure iron rod with a length of 300mm with a cutting machine, and then put it into the shot blasting machine for rust removal, and then send it to the batching area in barrels for batching. Raw material batching is carried out in the batching room. According to the performance, the raw material batching ratio is weighed and placed in the raw material tank, and then sent to the vacuum casting furnace.
(2) Vacuum casting
①Vacuum casting: after all the rare earth metals and non-rare earth metals in the crucible in the vacuum casting furnace are melted and reacted completely, the alloy melt is slowly poured into the middle casting bag by tilting the crucible, and the molten metal alloy liquid is evenly poured to the rotating water-cooled copper roller through the middle bag. Pouring temperature is controlled between 1350 ℃ and 1450℃. Under the dual action of rapid cooling and high speed rotation (commonly known as quick setting strip), the alloy liquid rapidly condensed into NdFeb alloy flakes with thickness of 0.25 ~ 0.35mm.
②Cooling: NdFeb alloy flakes are collected into the water-cooled disk under the casting cold roll for secondary cooling. Layout on the disk rotating device can increase the cooling rate of NdFeb alloy sheet, after waiting for alloy sheet temperature cooling below 60 ℃, lift the state of micro negative pressure in vacuum induction furnace, using air displacement emptying of argon, then open the oven door artificial staging the alloy sheet into special stainless steel barrel or into next working procedure.
③Product quality inspection: each furnace products should be sampled for quality inspection to confirm whether the product composition and performance meet the quality requirements, qualified products into the next process, unqualified products back to refining.
(3) Hydrogen crushing: hydrogen crushing powder is the use of NdFeb hydrogen absorption before and after the volume will change, so as to produce a great stress in its internal cracking of the material, to achieve the crushing effect. Hydrogen crushing process can improve the efficiency of air mill, which is more than two times of the traditional process.
(4) Air grinding powder: the alloy powder after hydrogen crushing is loaded into the air mill, under the action of high-pressure nitrogen at the pressure of 0.7 ~ 0.8MPa, the collision between the powder and further refined, and through the classification system to obtain the particle size of 3 ~ 5μm magnetic powder.
(5) Molding: after the powder is evenly mixed, 1.5t ~ 2.5T DC magnetic field is applied under nitrogen protection atmosphere to make the magnetic powder orderly arranged along the direction of the external magnetic field, and the pressure of 0.1-1t /cm 2 is used to press the powder. After pressing, a reverse magnetic field of about 0.2 ~ 0.5 T is still needed to demagnetize the billet.
(6) Sintering: the powder billet is placed evenly in the material tray, and then sintered in the vacuum sintering furnace (in the vacuum environment, the temperature is maintained at 1000 ~ 1100℃), to obtain the relative density of not less than 90% of the sintered billet.
(7) Machining: according to customer’s requirements, using grinding, drilling, wire cutting and other mechanical processing methods, the NdFeb blank is processed into a certain shape and size (square, round, ring and other shapes) of magnets.
Post time: Dec-13-2020