Standard comparison of rare earth NdFeB permanent magnet products at home and abroad

In this paper, the product standards of rare earth Nd-Fe-B permanent magnetic materials in China, IEC, Japan and the United States are compared and analyzed, and the countermeasures and suggestions for the development of rare earth permanent magnetic materials industry are put forward, so as to provide reference for the foreign trade and technical improvement direction of rare earth Nd-Fe-B permanent magnet manufacturers in China.

Among the new rare earth materials, the demand for rare earth permanent magnetic materials is the largest, accounting for about 25% of the total consumption, and it is one of the products with large export scale and added value, and fast export growth. China has listed the rare earth permanent magnet industry as a high-tech industry, and governments at all levels have issued relevant policies to encourage the development of rare earth permanent magnet industry. The consumption of rare earth permanent magnetic materials is the largest, and the most representative type is NdFeB permanent magnetic materials. Among them, sintered NdFeB permanent magnetic materials are the most widely used rare earth permanent magnetic materials, accounting for more than 90% of the global output of rare earth permanent magnetic materials. In recent years, with the rapid development of China’s rare earth permanent magnet enterprises and the impact of rare earth resource price adjustment, the global rare earth NdFeB permanent magnet material industry has gradually transferred to China. In order to find out the differences and reasons between China’s rare earth NdFeB permanent magnet products and foreign products, and further stabilize and expand the export target market, this paper conducts a comparative study between China’s rare earth permanent magnet materials standards and international and foreign standards by collecting and combing standards, translating texts and comparing key indicators.

Comparison of standards at home and abroad

The current product standards of rare earth NdFeB permanent magnetic materials in China include GB/T13560-2017 sintered NdFeB permanent magnetic materials [1], GB/T18880-2012 bonded NdFeB permanent magnetic materials [2], GB/T34495-2017 hot pressed NdFeB permanent magnetic materials [3], GB/T20168-2017 fast quenched NdFeB permanent magnetic powder, GB/T34490-2017 regenerated sintered NdFeB permanent magnetic materials and GB/T34494-2017 hydrogen crushed NdFeB permanent magnetic materials Boron permanent magnetic powder “6 national standards. The international standard is formulated by IEC (International Electrotechnical Commission), namely: IEC60404-8-1 “magnetic materials Part 8: Specification for special materials section 1 Standard Specification for hard magnetic materials” (2015) [4]. The standard for rare earth NdFeB permanent magnetic materials is a part of the Standard Specification for hard magnetic materials. Japan, the United States and India are the foreign countries to formulate the product standards of rare earth permanent magnet materials. Japanese industrial standard jisc2502:2019 “permanent magnet materials” is implemented in Japan, and ASTM A1101-2016 “standard technical specification for sintered and fully dense NdFeB permanent magnets” issued by ASTM International Standards Organization is implemented in the United States. India also issued a rare earth permanent magnet material standard in 1998, which only made general provisions on material requirements without specific index requirements. The main technical indexes of rare earth NdFeB permanent magnet materials are magnetic properties and size. Therefore, this paper compares and analyzes the differences of main magnetic properties and size indexes between domestic and foreign standards.

Main magnetic properties

There is no corresponding brand between Chinese standards and international and foreign standards.
According to the level of intrinsic coercivity (Hcj) in Chinese standards, the grades of Chinese standards are classified. Therefore, this paper compares and analyzes the grades of Chinese standards with those of international and foreign standards with similar intrinsic coercivity.

Sintered NdFeB permanent magnet materials

(1) Comparative analysis of GB/T13560-2017 and IEC60404-8-1-2015
According to the intrinsic coercivity (Hcj), China can be divided into seven categories: low coercivity n, medium coercivity m, high coercivity h, ultra-high coercivity sh, ultra-high coercivity uh, very high coercivity EH and very high coercivity th. The brands similar to China’s intrinsic coercivity in IEC standards correspond to China’s n, m, h, uh and eh categories respectively, but not to China’s SH and th categories. The main magnetic property parameters of national standard class n brand are similar to those of IEC standard. See Table.1.
Table.1 Comparison between GB/T13560-2017N and IEC60404-8-1-2015

There are 9 kinds of N grades in China’s Sintered NdFeB permanent magnet material standard, 6 more than the approximate grades in IEC standard, the intrinsic coercivity is generally higher than that in IEC standard, and the maximum energy products of 7 grades are higher than that in IEC standard, only 2 grades are lower than that in IEC standard; there are 8 kinds of M grades in China, and 3 corresponding approximate grades in IEC standard. According to the comparison, the intrinsic coercivity of Chinese M-class brand is set at 1035ka/M and 1114ka/m, and the intrinsic coercivity of IEC standard is set at 1000ka/M and 2000kA / m. It can be seen that the intrinsic coercivity of Chinese M-class brand is in the middle of the same kind of IEC standard, but there are 6 brands with the maximum magnetic energy product greater than 300kj/m3 in China, and only 1 in IEC standard; there are 8 Chinese H-class brands, and the corresponding IEC standard is similar Number three. Through comparison, it can be seen that the intrinsic coercivity of 2 of the 8 brands of Chinese class H is lower than IEC standard, the others are higher than IEC standard, and the maximum magnetic energy product is generally higher than IEC standard; the intrinsic coercivity of 7 brands of Chinese class SH is 1512ka/M and 1592ka/m respectively, and the maximum magnetic energy product range is 260-380kj/m3, while there is no coercivity brand in IEC standard; the intrinsic coercivity of 7 brands of Chinese class uh is 1512ka/M and 1592ka/m, and the maximum magnetic energy product range is 260-380kj/m3 There are 4 corresponding IEC standards. Through comparison, we can see that all kinds of magnetic properties of China’s uh class are higher than those of IEC standard, especially high-performance brands; there are 7 eh class brands and 2 corresponding IEC standard approximate brands. Through comparison, it can be seen that the EH intrinsic coercivity of China is equivalent to IEC standard as a whole, but the maximum magnetic energy product is generally higher than IEC standard; China has also set up 5 th brands, the intrinsic coercivity is 2627ka/M and 2786ka/m respectively, and the maximum magnetic energy product ranges from 220kj/m3 to 300kj/m3, but there is no high-performance brand in this range in IEC standard. To sum up, there are 35 more brands of Chinese standard products than international standards, and the diversification of brands is more conducive to the selection of materials by users. Through the comparison and analysis of main magnetic properties, the overall level of magnetic properties of Chinese standard products has reached the advanced level of international similar products, and China has 11 more high-performance brands of SH and th than IEC standards.

(2) Comparative analysis of GB/T 13560-2017 and JIS C 2502:2019
Compared with IEC standard, JIS C2502:2019 standard has deleted 5 brands with lower magnetic properties which are no longer produced, and added 3 brands with high performance. Other brands and index parameters are consistent with IEC. After Japan stopped the production of some products with lower magnetic properties, the magnetic properties of the brands set were improved as a whole. Among the three added high performance brands, refeb 350 / 130 is similar to class H brand in China; refeb 310 / 170 is between class sh brand and class uh brand in China; refeb 290 / 200 is similar to class uh brand in China. On the whole, there are 37 more brands of Chinese standard products than Japanese standard products, and the distribution range of magnetic properties parameters is wide. The overall level of magnetic properties has reached the advanced level of Japanese similar products.
(3) Comparative analysis of GB/T 13560-2017 and ASTM A1101-2016
15 brands set in American Standard [Hcj 875ka/m, 955ka/m, (BH) max 222-407kj/m3] are similar to Chinese n-class brands; 10 brands are similar to Chinese M-class brands [Hcj 1114ka/m, (BH) max 222-385kj/m3];
Ten brands are similar to Chinese class H brands [Hcj: 1353ka/m, (BH) max: 207-370kj/m3], nine brands are similar to Chinese class SH brands [Hcj: 1592ka/m, (BH) max: 207-355kj/m3], eight brands are similar to Chinese class UH brands [Hcj: 1989ka/m, (BH) max: 207-333kj/m3];
Four brands are similar to Chinese EH brands [Hcj: 2387ka/m, (BH) max: 222-281kj/m3]; three brands are similar to Chinese TH brands [Hcj: 2785ka/m, (BH) max: 207-244kj/m3]]. Through comparison, it can be seen that there are 60 brands in American Standard, 7 brands more than that in China. Among the brands with different magnetic properties, the intrinsic coercivity setting values are relatively uniform, but the setting range of maximum magnetic energy product is relatively wide, which reflects that the diversified demand of American brands is mainly reflected in the parameter of maximum magnetic energy product. In general, the magnetic properties of Chinese standard and American Standard are equivalent.
(4) Comparative analysis of GB/T 34495-2017 and JIS C 2502:2019
The sintered NdFeB permanent magnetic materials produced by hot pressing process in China and Japan have been industrialized. Therefore, both China and Japan have formulated standards for hot pressed Nd-Fe-B permanent magnet materials. According to the Chinese standard, the sintered NdFeB permanent magnet materials produced by hot pressing process include hot pressing isotropic permanent magnet (HP), hot rheological bulk anisotropic permanent magnet (hd) and thermorheological ring. In this case, there is only one kind of sintered NdFeB permanent magnet material produced by hot rolling process in Japan, which is anisotropic permanent magnet. Therefore, this part only compares the anisotropic permanent magnets in the two standards.
According to the intrinsic coercivity, hot pressed Nd-Fe-B permanent magnet materials in Chinese standard can be divided into nine categories: N, M, H, SH, UH, EH, AH, ZH and L. there is no heat flux bulk anisotropic permanent magnet (hd) in category M and H. Chinese standard sets three grades for class N anisotropic permanent magnet (hd), while Japanese standard sets one grade for class sh anisotropic permanent magnet (hd), and Japanese standard sets one grade for class sh anisotropic permanent magnet (hd), whose magnetic properties are lower than Chinese standard. By comprehensive comparison, the anisotropic permanent magnet (hd) brand set in Japanese standard is located between class n and class uh brand in China, while the rest brands in China are located between class n and class ZH, that is, the high coercivity product brand is the main brand, which reflects the relatively high level of hot pressing technology in China. Besides producing many kinds of hot pressed Nd-Fe-B permanent magnet materials, it can also be produced High performance brand products.

Bonded NdFeB permanent magnet materials

(1) Comparative analysis of GB/T 18880-2012 and IEC 60404-8-1-2015
China has set up a low coercivity class L Brand for compression molding bonded NdFeB permanent magnet materials, and all magnetic properties are lower than IEC standard; six class m brands are set, and only two corresponding IEC standard similar brands are set, which is equivalent to the intrinsic coercivity of China standard, but the maximum magnetic energy product of two Chinese brands is lower than IEC standard; China has also set up a class H brand, and the corresponding IEC standard similar brands There is also one whose magnetic properties are lower than the Chinese standard; China has set up six M-class brands for injection molding bonded NdFeB permanent magnet materials, and there are six similar brands in the corresponding IEC standard, and the intrinsic coercivity of three brands is higher than the Chinese standard, and the maximum magnetic energy product of one brand is higher than the Chinese standard; China has also set up one H-class brand, and there are three similar brands in the corresponding IEC standard, including one The intrinsic coercivity is higher than Chinese standard, but the maximum energy product of two brands is lower than Chinese standard.
To sum up, among the 12 brands of IEC 60404-8-1 bonded Nd-Fe-B permanent magnet materials, 9 are produced by injection molding, and only 3 are produced by compression molding. This reflects that there are more varieties of Nd-Fe-B injection molding magnets in the international market, while 8 are produced by compression molding in the 15 brands of Chinese standard, and the brands of injection molding are in GB/T Four brands have been added to 18880-2002, reflecting that more and more Chinese enterprises adopt injection molding. The Chinese standard also sets up the brand of low coercivity and high remanence with Chinese characteristics, which can meet the demand of the international market. The overall comparison shows that the magnetic properties of the Chinese standard generally reach the international standard level.
(2) Comparative analysis of GB/T 18880-2012 and JIS C 2502:2019
Compared with IEC standard, JIS C 2502:2019 standard adds two new brands of refeb 87 / 95p and refeb 95 / 67p with high performance in compression molding bonded NdFeB permanent magnet materials, and other brands and index parameters are consistent with IEC. In general, the number of compression molding and injection molding brands in Chinese standard is equivalent to that in Japanese standard, and the overall magnetic properties are also equivalent.

Table 2 Comparison of similar brands between GB/T 18880-2012 and IEC 60404-8-1-2015

Dimensions

Chinese standards, IEC standards, Japanese and American standards all emphasize that the dimension requirements shall be determined by the supplier and demander through negotiation, which is determined by the application characteristics of NdFeB permanent magnet materials. However, the Chinese standard, IEC standard and Japanese standard still put forward the basic size requirements for all kinds of rare earth permanent magnet materials, while the American Standard does not. For the dimension deviation requirements of sintered NdFeB permanent magnet materials, the Chinese standard is equivalent to IEC standard. Bonded NdFeB permanent magnet products have certain differences due to their different application fields and shapes. Three kinds of deviation values are designed in GB/T 18880-2012 bonded NdFeB permanent magnet materials, and the deviation control is equivalent to IEC international standard.

Summary

From the setting of standard grades of NdFeB permanent magnet materials in China, due to technological progress or consideration of market demand, some parameters of the original grades are adjusted to make the configuration of parameters in the grades more reasonable. Meanwhile, some new grades are added to make the grades of NdFeB permanent magnet materials in China more complete. In addition, from the comparison of similar brands, it can be seen that China’s standard brands of NdFeB permanent magnet materials are actively in line with the international and foreign target markets, with more brands similar to IEC, Japanese and American standards, which is more in line with the development trend of international similar products and the actual needs of domestic product production. In general, China’s NdFeB permanent magnet material standards have reached the advanced standards of IEC, Japan and the United States, and even the highest performance brands of some categories exceed IEC, Japan and the United States standards. For example, the highest magnetic performance brands of N, m, h, SH, uh and th devices in the sintered NdFeB permanent magnet material standards are higher than those of IEC, Japan and the United States standards, which reflects that China’s Sintered NdFeB permanent magnet material standards have the highest magnetic performance brands The equipment and technology of boron permanent magnet material production have made great progress.

Analysis on the difference between domestic and foreign standards of rare earth Nd-Fe-B permanent magnet materials

Differences from the perspective of standard formulation and revision

From the perspective of standard formulation and revision, the Secretariat of IEC rare earth industry standard setting organization is set up in Germany. In the process of standard formulation and revision, Germany has absolute voice. Germany directly adopts IEC standard. Japan also has a strong voice in the process of IEC standard formulation and revision because of its obvious technical advantages and industry influence. Japan is in the process of rare earth permanent magnet material national standard formulation and revision Therefore, the Japanese rare earth permanent magnet material standard can be basically consistent with IEC standard except for adding some high-performance brands and new production process products. The United States also has a strong voice in the process of IEC standard formulation and revision. In addition to formulating national standards to meet the needs of the domestic consumer market, it also implements IEC standards. Although China is the largest producer of rare earth permanent magnet materials, it has little say in the process of IEC standard formulation and revision, so it is difficult to compare with IEC standard. This is also one of the reasons for the differences between Chinese standards and international and foreign advanced standards.

Differences from the perspective of production and application consumption

According to the production and application consumption of rare earth permanent magnet materials in various countries, Japan is one of the largest producers of rare earth permanent magnet materials. The overall production level of rare earth permanent magnet materials manufacturers is relatively high. In the process of standard formulation, the production demand of enterprises is easier to coordinate than that of China. The brand with lower magnetic properties is deleted from its latest revised national standard in 2019, and the brand with high performance is added See. The United States is a big consumer of rare earth permanent magnet materials, and its national standard brand setting is mainly affected by the application structure of rare earth permanent magnet materials. China is a big producer and exporter of rare earth permanent magnet materials. In terms of brand parameter setting, many standards have been close to international IEC standards as far as possible. For example, in the process of revising parameters of maximum energy product, China has fully referred to the production brands of foreign enterprises, narrowed the range of maximum energy product of several brands, and kept consistent with foreign enterprises as far as possible. Moreover, China is revising various categories of permanent magnet materials In addition, we fully investigated the domestic and international consumer market, fully referred to IEC international standards, Japan and the United States national standards and the enterprise standards of relevant well-known production enterprises in Japan, the United States and Germany, such as the enterprise standards of VAC, Hitachi Metals, TDK and Xinyue chemical company in Germany, and took the production demand factors of domestic enterprises into consideration There are many manufacturers of permanent magnet materials, and the level of production technology is uneven. In the process of making and revising national standards, it is necessary to coordinate the production needs of various enterprises. This is one of the reasons for the difference.

Differences from the perspective of process technology

The production process of rare earth permanent magnet materials has long process flow, many links and high technical requirements. It has high requirements for process design and process control, and the key technologies need to be realized through fine production process. For example, the level of milling process in the production process of sintered rare earth permanent magnet materials directly affects the purity and distribution uniformity of magnetic powder; the technology level of orientation molding process is low The accuracy of temperature control and automation in sintering process directly affect the stability of magnetic energy product. China’s rare earth permanent magnet material industry has developed with the introduction and absorption of technology. In recent years, the technology level has made great progress. However, the overall level of production technology of China’s rare earth permanent magnet material industry is still lower than that of foreign countries, and the development of technology level in each link of production is not balanced, which affects the main magnetic parameters of materials in varying degrees, and limits the brand parameter setting in the process of Chinese standard formulation and revision. Japan is a country that has the most advanced core technology in the production of rare earth permanent magnet materials, with more than 50% of the patents in the world, and covers all aspects of the production of rare earth permanent magnet materials. Its production technology level is higher than that of China as a whole. Most of the standards are high-performance brands, and the setting of parameters in the brands is more reasonable than that of China, which can better meet the requirements of high-performance brands in the global strategic emerging fields The demand for product No. This is also one of the reasons why there are differences between Chinese standards and foreign advanced standards.

Countermeasures and suggestions

Upgrading China’s competitive and characteristic standards to international standards

Both China and Japan have national standards for Nd-Fe-B permanent magnet materials produced by hot pressing process, but there is no standard for Nd-Fe-B permanent magnet materials produced by hot pressing process in IEC standard at present. Compared with Japanese standard, China’s hot pressing process can not only produce many kinds of hot pressed Nd-Fe-B permanent magnet materials, but also produce high performance brand products, with the technical level at the international advanced level. Through the efforts of the government, industry associations and other organizations, China can try to promote the standard of hot pressed NdFeB permanent magnet materials to the international level, obtain the recognition of IEC, strive to upgrade it to IEC standard, and take this as a breakthrough point to gain more voice in standard formulation and revision.

Improve the Chinese standard system

In recent years, developed countries pay more and more attention to environmental protection, and require that all imported products must meet the requirements of environmental protection. China’s rare earth NdFeB permanent magnetic material product standards and other categories of rare earth permanent magnetic materials have not put forward the requirements of radioactivity and pollutants exceeding the standard, and have not formulated the relevant inspection and testing methods and standards. Therefore, it is suggested that China improve the relevant standards, further improve the standard system of China’s rare earth permanent magnetic materials, and ensure the stability of product quality.

Strengthen the technical development of product performance, production process and new products, and break through patent barriers

As the world’s second largest producer of rare earth permanent magnet materials, Japan is at the international leading level in production technology and R & D, with more than 50% of the patents related to rare earth permanent magnet materials in the world, including most of the key core technology patents. China is the world’s largest producer of rare earth permanent magnet materials, but the overall level of production technology is still relatively low. The export standards of rare earth permanent magnet materials are mostly middle and low-end products, and high-end products still need to be imported in large quantities. The number of related patents only accounts for about 10% of the world, and there are few patents on key core technologies, which affects the export of China’s rare earth permanent magnet materials to a certain extent. In order to break through this obstacle, China’s rare earth permanent magnet material industry should further strengthen the technical development of product performance, processing technology and new products, optimize the parameter setting of standard middle-class brand through technical progress, and increase the proportion of high-performance brand in the standard; through the development of new technology and new products, apply for patents with new technology and new products, and break through the patent barriers to China The export of rare earth permanent magnet materials is hindered, and the product brands in Chinese standards are enriched.
Author: PENG Ying-zhim,MO Jia-lin,WANG Quan-yong,TANG Yan-qiong
Source: China Permanent Magnet Manufacturer – www.rizinia.com
Reference:

• [1] GB/T 13560-2017 sintered NdFeB permanent magnet materials
• [2] Bonded Nd-Fe-B permanent magnet materials (GB/T 18880-2012)
• [3] GB/T 34495-2017 hot pressed NdFeB permanent magnet materials
• [4] IEC 60404-8-1-2015 magnetic materials – Part 8-1: technical specifications for individual materials – hard magnetic materials
• [5] JIS C2502y2019 permanent magnet material
• [6] ASTM A1101y2016 Standard Specification for sintered and fully dense NdFeB permanent magnets