Product

Sintered Neodymium Iron Boron ( NdFeB ) magnet, the strongest one in the family of permanent magnets, has more than 10 times (BH)max comparing hard ferrite magnet. It is manufactured by powder metallurgical process with anisotropic character. The birth of NdFeB magnet offers possibilities of realizing new design idea, opening new field of application and having component design with compact figure and light weight but optimized performance. In contrast to SmCo magnet, NdFeB magnet is with almost double (BH)max, about 10% lower density and stronger mechanical strength such as bending strength and tensile strength. It also solves the problems of expensive cost and short supply of raw material due to its relatively abundant materials what are primarily comprised of iron, boron and rare earth element (principally neodymium).

In the past years, our sources were striving for contribution of excellent sintered NdFeB magnet to meet the frequently updated demands from market. Every year large amount of fund is invested for R&D，staff training, state-of-the-art manufacturing facilities and advanced monitoring devices. Today the sources have grown up as leading producers of NdFeB magnet in the world, and held several ten patents on manufacturing technology and modified equipment. Effective quality assurance system ISO9001, ISO16949/TS16949 and environment protection system ISO14001 have been introduced and authenticated by the third party. The sources are with capability of whole manufacturing process from raw material preparation to packing under one roof for facilitating quality control. In 2002, one of our sources imported 2sets automatic electric-plating line from Japan with functions of online monitoring and automatic liquid-feeding. These lines offered great help on improving coating quality particularly for high level coating requirement such as magnet of voice coil motor (VCM).

Nowadays some prestigious producers of NdFeB magnet in the world are also purchasing product from our sources for their trade business. The products are widely assembled inside motor, generator, sensor, switch, relay, meter, magnetic coupling, magnetic separator, electro acoustic, air compressor and magnetic resonance device for automatic control, automobile, computer, communication, consumer electronics, measuring instrument, household electric appliance, medical equipment, wind turbine generator system, mineral plant equipment, holding system and many other applications by rights of product superiorities:

Manufacturing Process, Magnet Shape & Dimensional Tolerance

Lying on geometry, property, batch quantity, size range, dimensional tolerance and structure, sintered NdFeB magnet is manufactured either by direct molding or by machining the molded magnet. Magnets of ring, disc, cylinder and block shape with reasonable size，proper property grade, fair dimension tolerance and regular dimension structure can be economically manufactured by die-pressing process. Machining process can realize sintered NdFeB magnet with irregular dimension ratio and complex geometries such as skewed arc segment, tapered cylinder, sphere and butterfly shape etc. Magnets with strict dimension tolerance, super big figure, extremely small size or high property grade are also merely available by machining process on molded products. Machining process also is the economic way to produce small quantity order by saving tooling cost. Grinding, slicing and EDM wire cutting are mainly applied to machine the sintered NdFeB magnet.

After sintering process, generally NdFeB magnet will be ground to get uniformity of dimension and homogeneity of flux outputting. The dimensional tolerance after coating process, largely determined by magnet size, is economically controlled within ±0.10mm. Smaller deviation of dimension also could be controlled even up to ±0.015mm if it is requested.

Due to high degree of brittleness and hardness, machining sintered NdFeB magnet is not so easy. At our sources, the experienced machining team is dedicating to realize magnets with complicated geometries and irregular dimension structure what were regarded impossible to sintered NdFeB magnet by other competitors. The EDM wire cutting is the most expensive machining method. They also invented some process to reduce using of EDM wire cutting specially in making arc segment type magnet. That makes production with competitive cost.

Low Weight Loss NdFeB Magnet

Research find out that adding certain percentage of cobalt together with aluminum, cooper and gallium in manufacturing NdFeB magnet can have magnet with better corrosion resistance and thermal stability than cobalt free one. After highly accelerated stress test (HAST) according to IEC 68-2-66 under conditions of 130℃, 2.7bar and 95% humidity, the cobalt contained NdFeB magnet shows lower weight loss. Furthermore, the Curie temperature is to be increased and the reversible temperature coefficient of remanence and intrinsic coercivity will be minimized. Laboratory test also convinces that the improved degree is determined by cobalt ratio in composition.

In the market there is great demand for low weight loss NdFeB magnet. Our source started development of this type magnet several years ago and has achieved great success. Old record shows that the weight loss of our “-LT” sub-grade NdFeB magnet is to be controlled less than 2mg/cm2 after HAST test for 240hours, meanwhile the reversible temperature coefficient of remanence and intrinsic coercivity can be minimized respectively up to -0.09%/℃ and -0.45%/℃.Today these typical values have been revolutionarily minimized in adjusting ingredient, upgrading equipment and innovating process. Information on the latest progress of these issues is available upon request.

Thermal Character and Heat Treatment (Aging)

The magnetic properties of NdFeB magnet are sensitively influenced by environmental temperature. Thermal characters including Curie temperature, maximum working temperature and reversible temperature coefficient of remanence and intrinsic coercivity are of the most important factors should be taken into account when having NdFeB magnet as option. The thermal characters of NdFeB magnet are dissimilar according to material grade. Especially the maximum working temperature and Curie temperature are respectively spans 80℃~230℃ and 310℃~350℃.

Remanence, coercive force and flux density of sintered NdFeB magnet will be decreased along with elevation of environmental temperature. Partial value losses are reversible along with falling of temperature, but partial losses are irreversible. The irreversible losses are dependent on magnet loading line and the maximum working temperature. To stabilize irreversible losses, additional heating treatment (aging) could be applied on magnetized magnet at temperature slightly higher their maximum working temperature for eliminating irreversible loss in advance. This kind of treatment is commonly adopted for magnets what will be assembled inside motor, generator and other applications with demand of stable running at high temperature. The heating temperature and period on individual magnet should be consulted with us.

Surface Treatment

The capabilities of corrosion resistance of sintered NdFeB magnet are considerably low due to active chemistry reactivity of neodymium what exists as free neodymium phase in boundary of inter-metallic grain of NdFeB alloy. The corrosion speed in normal atmosphere is slow. Under condition of high temperature and water or humidity, the corrosion will be accelerated. Thus surface treatment on sintered NdFeB magnet, mainly for protection purpose, is very necessary. Surface treatment also can prevent NdFeB magnet from magnetic particle on surface and keep magnet with good looking.

We offer several types surface treatment for customer choice. Each type of surface treatment possesses different character and function. Surface treatment can influences adhesive durability of magnet together with other component if assembling process is by gluing. Furthermore some types of coating can shield small partial magnet force. We will be pleased to offer solutions on coating type, glue type, coating layer thickness, surface tension force, curing temperature and other concerned issues if our customer has such kind of request. We also attach a comparison table on coating for your reference.

Anisotropic Sintered NdFeB Ring with Radial Orientation

The success of developing anisotropic sintered NdFeB ring with radial orientation is one of the symbols of our partner as a technical pioneer in the field of manufacturing sintered NdFeB magnet. Differing from technology of hot extrusion process invented by oversea competitors, our product is made by powder metallurgical process the same as manufacturing sintered NdFeB magnet with axial alignment. Depending on our technology, anisotropic sintered NdFeB ring can be radially magnetized; the numbers of magnetic pole is determined by magnetizing fixture and no need to be pre-fixed in pressing process; the magnetization could be treated as skew one with angle, the surface inductive flux distribution of magnet can be controlled as sinusoidal waveform.

The application of anisotropic sintered NdFeB ring with radial orientation extensively covers servo motor, spindle motor, stepping motor, power steering motor for automotive, generator, linear actuator, coupling and magnetic bearing. In contrast to gluing sintered NdFeB arc segments into a ring, anisotropic sintered NdFeB ring with radial orientation is with better homogenization of flux distribution at each pole, higher precision in external dimension, more reliable and easier assembly by omitting bonding segment for being a rotor. The invention also can substitute bonded NdFeB ring for some applications with advantage of stronger output of energy density.

Quality Assurance Capability

In addition to setting up effective quality assurance system ISO9001 and ISO16949/TS16949, our sources introduced full and state-of-the-arts equipments to monitor the NdFeB magnet quality. Usually we carry out below inspection or test in producing process and on the finished one. If customer has special requirement on inspecting item, please kindly discuss with us in advance.