As economic developments in China expand rapidly, bigger markets for industrial lasers and systems are pushing the industrialization of laser technologies. Today, domestic laser manufacturers meet most of the needs for low and medium power solid-state Nd:YAG lasers and systems and high-power CO2 lasers, up to 5 kW. The high investment to buy a laser system is still a major difficulty that has slowed the application of laser processing systems in industry.
History
In China, research activities in laser physics and technology, industrial lasers and applications began in the early 1960s. In September of 1961 the ruby laser was introduced in China, just 15 months after Dr. Ted Maiman invented the first ruby laser. In 1963, Chinese engineers used this laser to drill holes in metal molds and sapphire gears used in watches. However, because of the cultural revolution, progress in laser technology stopped during the period 1966–1976.
After the cultural revolution, fundamental research on laser technology, laser radiation control (optical resonators and nonlinear optics), theory and application of laser-material interaction and fundamentals of laser materials processing restarted. Increased attention was paid to high-power lasers and laser systems. The first two 5-kW and 10-kW transverse-flow CO2 lasers were developed at the Institute of Laser Technology (ILT) of Huazhong University of Science and Technology (HUST) in 1981, 1985 and 1989, respectively. In 1989, this institute developed fast-flow CO2 lasers with output up to 1.5 kW.
Nd:YAG laser welding and marking systems for industrial applications started in the mid-1980s. In the early 1990s, Nd:YAG laser welding systems, with fiber-optic beam delivery, produced simultaneous multi-spots for welding. These were successfully used in the assembly of fiber-coupled components and the metal parts of kinescope electron guns. Meanwhile, research on laser cutting, welding, surface modification, marking, scribing, trimming, pulsed laser deposition and laser direct forming of 3-D components was being done in the universities and institutes, which played an important role in promoting the industrial application of lasers and laser processing systems.
At the end of 2001, several thousand industrial lasers and laser processing systems had been set up in different enterprises. Most of these are low- and intermediate power (up to 100 W) CO2 and Nd:YAG (up to 250 W) lasers made by domestic laser enterprises. Today China makes commercial high-power transverse-flow CO2 lasers with output up to 5 kW, and fast-axial-flow models up to 3 kW. Commercial lamp-pumped Nd:YAG lasers up to 1 kW CW and 500 W average power for pulsed lamp-pumped lasers are available. The maximum output for diode-pumped Nd:YAG is only about 80 W at this time. Other lasers also in use are imported mainly from Germany and the United States.
R&D on lasers and systems
Currently more than 100 laser and laser processing centers, laboratories, institutes and universities are engaged in R&D on lasers and applications. Besides those already mentioned, several other important R&D centers and universities are shown in Table 1. These universities and institutes have chairs on laser materials processing and are staffed by graduate scientists and engineers who are specialists in this field.
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Most of these organizations using industrial lasers and laser processing systems have received financial support or grants from different departments of the government such as the Ministry of Science and Technology of China, Ministry of Education, Chinese Academy of Sciences (CAS), National Natural Science Foundation of China (NSFC) and ministries that are related to the advanced manufacturing technology. The most well known include the National Scientific Foundation of China (which supports basic research), 863 Hi-Tech Research and Development of China and Key Technologies R&D Programs from the Ministry of Science and Technology of China (which supports the programs of key technologies for engineering application and industrialization). Also, local governments have been giving continuously strong support for laser technology.
Many of these organizations have received R&D contracts from domestic industrial companies through a strong relationship that is highly beneficial to promoting laser technology and industrial applications. Applications developed from basic and applied research on laser materials processing were introduced into production in industries such as automobile, aircraft, metallurgy, mechanics and electro-engineering.
Manufacturers
Rapid economic development began in the early 1990s, when China switched to a market system, the symbol of which is the number of companies using lasers and systems. There are now more than 100 companies manufacturing industrial lasers and systems, some of which came from the institutes of laser technology and application and others that grew from small private laser companies. Most of these were established in recent years. They manufacture industrial lasers, laser components or laser machining systems that represent more than 90 percent of the market with products for marking, scribing, trimming, cutting, welding, surface modification, micro-machining and direct forming of prototype components.
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The most active manufacturers today are shown in Table 2. The availability of industrial laser products is usually about three to six months and most of the products are sold in mainland China. A small number of laser systems are sold in Southeast Asia, and a few units are even exported to the U.S.
Industrial applications
At the end of 2002, in Guangdong Province (one of the most active economic areas in China), more than 1500 CO2 and Nd:YAG laser marking systems for electronic components were being used for keyboards of PC computers and other components. Almost 800 laser welding systems are used in battery sealing welding, because almost 90 percent of the batteries in the world are made in China, especially in Guangdong Province. More than 100 laser scribing systems are used to scribe the crystals for solar batteries and chips, and about 40 units of three-beam laser welding systems are used in the information technology industry. These laser systems are mostly made by the domestic companies mentioned in Table 2. There are more than 100 laser jewelry welding systems, 90 percent of which come from abroad, mainly from Italy. More than 20 high-power CO2 laser cutting systems are used for sheet metal cutting.
In the triangle area of Yangtze River (including Shanghai and the cities around it), there are also markets for hundreds of lasers and laser processing systems. For example, in Qiaotou Town, a small town in Zhejiang Province, more than 100 laser marking systems have been marking buttons (for clothes) day and night for three years. This town shares more than 40 percent of the button market worldwide.
In China, most of the high-power laser systems are bought by industrial enterprises engaged in automobile and aircraft manufacturing, shipbuilding, railway transport, metallurgy and electro-technical equipment. The main processing applications are cutting (metal sheets, plastics, woods, clothes and cables), welding (diamond saw blades, gears and precision welding of small components), surface hardening or cladding (rolling mills, mold and die, engine valves, turbine blade, bearing rings) and drilling (turbine blades for aircraft engines, sieves). Less than 100 job shops act as laser processing centers serving the medium and/or small companies that do not have enough work to buy their own laser processing systems. In the past five years, laser rapid prototyping technology has developed quickly, with tens of laser rapid prototyping systems in different enterprises.
The market for industrial lasers and related systems is growing every year. About 1000 units were sold in 2001, most of which were supplied by Chinese manufacturers. Over the last two years laser marking, scribing and welding systems with medium and low power were the dominant laser and laser systems sold. More laser cutting systems are being bought by machine building companies and job shops. There is also a large market for laser micro-machining systems. However, in most of the cases, it is price rather than the technology that retards its application in industry.
Foreign companies are rapidly entering the laser and laser processing markets. For example, ThyssenKrupp Tailored Blanks GmbH and the Wuhan Zhong-Ren Automobile Parts and Components Co., Ltd. recently commenced tailored blank welding in Wuhan. The laser-welding lines will produce 60,000 tons annually. The Trumpf Group has established a laser processing center in Jiangshu Province, where the company exhibits its laser products.
Future
The volume of the industrial lasers installed in China is low compared to advanced countries. However, economic stimulation of Chinese enterprises is speeding up their progress to develop advanced lasers and laser processing systems. DPSS Nd:YAG lasers with output of 100 W or more will come into industry one year from now and 10-kW CO2 lasers will be commercialized within two years. The National Engineering Research Center for Laser Processing in HUST is starting a joint research program with an American company to develop the fast-flow, high-beam-quality 3- to 6kW CO2 lasers, which can meet the market needs in the near future.
At the same time, the R&D centers and universities are developing advanced industrial laser processing systems and trying to integrate advanced lasers bought from abroad into processing systems. For example, Wuhan Huagong Laser Engineering Co., Ltd. has successfully set up a laser texturing system for cold rolling steel sheets for Kuming Iron and Steel Company, and this company has also developed advanced laser welding systems for a high silicon sheet production line in Wuhan Iron and Steel Company to connect the acid pickling and rolling process together. In both cases the lasers are made by companies in Germany and the U.S., but the mechanical and controlling systems as well as the welding technology are provided by domestic manufacturers. Thus the prices for the whole welding systems are much cheaper than those from abroad directly.
Prof. Xiaoyan Zeng is the director of the Laser Processing Department, National Engineering Research Center for Laser Processing, Huazhong University of Science and Technology. Contact him at e-mail [email protected].