Professional Knowledge

Lasers of different types
1. Writer:Hideki Harada

President, Hitech Association Ltd. (HTA) Fukaya Japan Chairman, The Japan Association of Bonded Magnet Industries, (JABM) Tokyo Japan China Mag 2002, Intertech Conference, October 17. 2002. In Beijing

2. Abstract

I have studied comparison with Chinese and Japanese magnet business at the point of neutral and professional position. Sintered ferrite and sintered RE business, China and Japan have market segregation. There are main reasons of it. In some bonded magnets, the raw materials are same in both countries, therefore it is very difficult to find the differences. Anisotropy and clean technology are only existed as the difference.

3. Back grand of the study

I have developed in a company hard ferrite and rare earth magnets business. They are sintered and bonded magnets. At the beginning of my job around 1960, I have visited Europe and USA magnets factories. I have studied a lot there. After retirement the company in 1994, I got the jobs of the above. I have received invitation from many Chinese magnet companies. More than 20 companies I have visited in these years. I got the chance every year. Especially in June 2002, I made a mission of JABM to study up date China magnets business. We have visited 13 companies in 8 cities. They are large and small, traditional and venture, RE, Alnico, and ferrite, sintered and bonded. Some of them I have visited first time, others I have been already. I was very happy to talk with top management in every company. And also I have received many production samples from these companies. Some of them the properties were acceptable level for some application. I have recommended starting the business. I can understand the Chinese industrial properties.

In Japan, the association system is working. One of the association jobs is to make production statistical data. Japanese data of the report is collected from the association data. But others, Asia and China, they are estimated value by myself from many information. Please give me more information and suggestions to build up the data more precisely. In some day I would like to establish association in China too.

4. Sintered hard ferrite magnets

The comparison shown of hard ferrite production in Japan, China and Japan other countries. Japan inland at present they are producing mostly arc segment magnets for automobile. Speaker and small motor magnets already moved in other countries. Special production process like radial orientation still remained in Japan. In China 85-90% of the weight is Speaker and similar shape flat ring magnet for E. cooker. Motor or generator segment magnets are produced in China too, but not so much. The properties are normal class not too high.

In around 1970, automobile motor revolutionary changed from winding to ferrite magnet type. It started using ring isotropic magnet. The properties of segment magnet have been improved by anisotropic wet press technology. Finally they applied high performance magnets. Ferrite has 50 years history. There are not so sever patent issue. However at present, China and Japan have market segregations.

In Japan in 1970, a steel manufacture cooperated to produce optimum ferric oxide for ferrite by Ruthner process. It was very low chlorine, very small particle size, and very narrow particle distribution. And also in Japan there was large automobile market. Therefore developing automobile motor magnet market existed in Japan. In China in near future automobile market will be growth. If some steel manufactures in China will cooperate to ferrite producers to make optimum ferric oxide, China automobile segment magnets will take success.

Hard ferrite motor segment magnets have more sever competition with RE magnets. If the price level of RE magnets will become less than $30-40/kg, automobile revolutionary change will occur from segment ferrite to RE. The weight and size of motors will reduce 50% or more, with 42 volts design change. Thin wall bonded RE magnets will take the chance.

5. Rare earth sintered magnets

Table 2 is shown comparison of RE sintered magnet production in Japan and China. Japan RE sintered magnets production still remains in Japan. The main reason of it is patent limitation. My China visit of this year, I was disappointed that there was not high performance RE magnets production in China. In China book mold and double press process is almost standardized. The capital investment of past and near future also they applied the same process. I know in China there is big market of 30-40 level magnets. They are too busy to meet the market. The process existed in China is good and to meet the market. The efficiency of capital investment is also good.

Table 3 is shown comparison with Chinese and Japanese NdFeB sintered magnet production process. The properties level of these is shown in Fig. 2. With Chinese typical process, it is very difficult to get over 45MGO. More over small magnet after big grinding process from block magnet, and surface treated, most of actual magnet B_H curve shown in Fig. 3. There is a lot of surface damage on the products. The square of B-H curve is mostly not good. This shows reliability of the material is not good. I believe Japanese process is theoretically correct. Near net shape process is also very important to manufacture parts by powder metallurgy. Surface treatment also must be applied in clean room. Therefore in China thermal properties and not so big demagnetize power application like speaker and small motor market existed. VCM and large motor magnets need very important material reliabilities and cleanness, strength for thermal and demagnetize power. These markets existed in Japan. China and Japan have market segregations here too.

I like to explain an example, how important near net shape process is. Quartz watch magnets, OD 1.5, ID 0.5, thickness 0.5mm, had been manufactured by block to final shape by machining process 20 years ago. Nowadays we are manufacturing with multi cavity single press process, 1.5 second/cycle, very little grinding, production volume is 400M. The cost may be competed with Chinese magnets.

6. Bonded ferrite magnets

Comparison of Chinese, Japanese and S.E. Asia shown bonded ferrite magnets production. The properties of bonded magnets are depended upon powder properties. Flexible ferrite bonded magnet is applied usually orientation by calender roll. Flat shape powder for flexible magnet in China and Japan is almost same level now. The plastic binder materials of flexible magnet are also almost same. Therefore at present it is very difficult to find the difference between Chinese and Japanese flexible ferrite bonded magnets. Japanese advantage in this category is only remain the thickness is less than 0.2mm anisotropic sheet. Thin sheet production, it is very difficult to use calender roll. Extrusion process is much better to keep tight tolerance. In Japan small and special application market only remains.

Rigid ferrite bonded magnet is another story. To make the orientation, it is essential to use magnetic field. Keeping high density, easy rotation by low field, these are important properties of powder. Multi cavity with magnetic field injection technology is quite difficult one. In China and in S.E. Asia, there are lots of isotropic injection molding for TV focus magnets, but not so many magroll and small motor magnets. Some Japanese company recently started to transfer the anisotropic injection technology to China. In these 2-3 years market situation will change. Now copy and printer manufactures are moving into China. Therefore magroll manufacturing is also moving into China. The rigid bonded ferrite production will decrease in Japan.

7. RE bonded magnet production

Table 5 is shown comparison of bonded rare earth magnet production in Japan, China and S.E. Asia. At present main raw material of RE bonded magnet is MQ powder. Other powder may be very little. In China there are not Nd magnets patents. Therefore we can find some other powder than MQ. Magnetic properties of isotropic bonded RE magnets in Japan, S.E. Asia and China are almost same. The differences of them are cleanness of the surface. At present motor magnets for HDD, Japanese manufactures are supplying only, because request of dust free. Japanese manufactures moved already to China and A.S. Asia already. Therefore production in Japan remains only special application only. In China there are many very active manufactures. The production amount will increase rapidly in China.

Japanese RE bonded manufactures are making efforts to establish new RE bonded materials. Anisotropic SmFeN and NdFeB bonded magnets are good examples. I have estimated these new material production is 160ton in 2002.

The technical trend of automobile motors is light, small size and low noise. To use sintered ferrite segment, there is the technical limit. If the cost is almost same people will like to use RE bonded ring magnet for new BLDC motor. Motor design will be optimized, thickness of ring should be less than 2mm, may be 1mm is acceptable. Pole numbers of magnet is 4-8 poles, not 2 poles. Magnet weight will be 1/3 to 1/5, motor weight will be almost half.

8. Conclusion

1.I have compared with Chinese and Japanese magnet business at the point of neutral and professional position.

2.Sintered hard ferrite, China and Japan have market segregation. Speaker and ring flat type magnets are mainly in China, automobile crack free segment magnets are mainly in Japan. The reason of it is raw materials and market situation.

3.Sintered RE magnet, China and Japan have market segregation. Speaker and small motor magnets, having 3O-40MGO levels, are mainly in China, VCM and large motor, dust free clean magnets, having 4O55MG0 levels, are mainly in Japan. The reason of it is process differences. In Japan manufacturers are applying near net shape process and stoichiometric composition. In China there is big market of 30-40MGO magnets.

4.Flexible ferrite magnet, there is not so big technical differences in both countries now. Applications only are different.

5.Rigid ferrite magnet; isotropic is in China, anisotropic is in Japan. Anisotropic multi cavity injection mold technology is now transferring from Japan to China.

6.Isotropic RE bonded magnet; technology is unified in both countries. Cleanness is only different now.

7.Anisotropic RE bonded magnet; in Japan at present, developing time. The target of RE bonded magnets is 42 volts system automobile motors to compete sintered segment ferrite.

9. Acknowledgment

Thank you very much sincerely for my visited Chinese Companies, plant tour and wonderful reception.