Lasers have become accepted "tools" by a number of industries. Everything from cars to heart pacemakers to greeting cards are now using lasers to cut, drill, clad, heat treat, and weld/join. The market for industrial laser systems is expanding. For the first quarter of 2004 the sales in lasers systems increased 40% to over $120 million1. Some of this increase in sales may be due to the fact that lasers are now considered reliable and have proven to be economical.
The primary industrial laser systems today are the CO2 and Nd:YAG (lamp pumped) lasers especially at the higher powers. Both laser designs have evolved in power, beam quality, and reliability. At the same time laser manufacturers have developed methods to decrease the fabrication cost for the lasers. While these improvements have had a major impact on the operating cost of lasers, significant additional improvements do not seem possible in the near future for these lasers. As a result other advances in laser technologies (diode, diode pumped Nd:YAG, disc, and Yb fiber) are being examined.
The use of lasers for welding has exhibited tremendous growth over the last decade for improving efficiency and
reducing costs in a broad range of industries. Much of these successes are based on the development and availability of
enabling technologies, which include improvements in process understanding, enhancements in laser sources and
systems, and continued development and progression in process technology for laser beam welding of macro and micro
components. The development of accurate numerical simulation techniques has provided an unprecedented opportunity
to view the transient nature of laser processing. Advancements in laser source technology include the introduction of
higher-power Nd:YAG lasers, utilizing diode pumped rods or disks, and fiber lasers, both providing the capability for
fiber optic beam delivery. Although CO2 laser systems continue to dominate thick section welding, this influence will be
challenged by emerging source technologies, namely high power fiber lasers. One of the most promising advances in
laser process technology is laser-arc hybrid welding, which is seeing considerable interest worldwide and is currently
being evaluated for various applications within heavy industry and manufacturing. The benefit of hybrid welding is the
synergistic effect of improved processing rates and joint accommodation over either of the processes viewed separately.
Other processing methods are also being developed to increase the utility of laser beam welding for industry, such as the
use of dual beams and beam manipulation. The continued advancement in process knowledge is seen as a key element
for facilitating the development of new processes and encouraging the acceptance of new source technology.
New laser technologies challenge the established laser workhorses. The strengths and weaknesses of some of the major players for material processing will be covered. Applications and comparisons will be covered with results in the areas of cutting, welding, and metal deposition. Capability, trends and performance needs for the future will be included for industrial applications.
Breinan and Kear first reported fabrication of three-dimensional metallic components via layer by layer laser cladding in 1978 and subsequently a patent was issued to Brown et al. in 1982. Recently, various groups are working world wide on different types of layered manufacturing techniques for fabrication of near net shape metallic components. Integration of lasers with multi-axis presently available CNC machines, CAD/CAM, sensors and powder metal delivery through co-axial nozzles along with the laser beam are the main innovations for fabrication of 3-Dimensional components. Continuous corrective measures during the manufacturing process are necessary to fabricate net shape functional parts with close tolerances and acceptable residual stress. The closed loop Direct Metal Deposition(DMD) System, using an optical feedback loop along with a CNC working under the instructions from a CAD/CAM software, indicate that it can produce three dimensional components directly from the CAD data eliminating intermediate machining and reduces final machining considerably. This technology is now being commercialized.
Low power fiber lasers began entering the commercial markets in the early 1990s. Since their introduction, fiber lasers have rapidly progressed in power levels level with greatly improved beam quality to the point where they now exceed any other commercial material processing laser. These lasers, with single mode operation to 1 kilowatt and multi-mode operation to beyond 20 kilowatts, have high wall plug efficiency, an extremely compact footprint, are maintenance free and have a predicted diode life beyond 100,000 hours of continuous operation.
Fiber lasers are making inroads into the scientific, medical, government, and in particular, material processing markets. These lasers have greatly expanded the application umbrella due to their unparallel performance combined with the ability to operate at different wavelengths, address remote applications and be propagated great distances in fiber.
In the material processing markets, fiber lasers are rapidly gaining share in the automotive, microelectronic, medical device and marking markets, to name a few. The single mode lasers are redefining process parameters that have been accepted for decades. The high brightness multimode-kilowatt class lasers are achieving speeds and depths greater than comparable powered conventional lasers while providing the only commercial material processing lasers operating beyond 6 kilowatts at the 1 micron region.
Micromachining materials with ultrashort pulses of light offers a new modality for processing materials that can produce a low heat-affected zone, is not wavelength dependent, has reduced contamination, produces highly repeatable results shot-after-shot, can create both micron and nanometer scale features in materials and has the ability to machine just about anything. This article will provide an overview of the processes involved in micromachining with ultrafast lasers, show how they differ from traditional methods, and discuss the future of this important technology.
As tools for use in industrial applications, High Power Direct Diode Lasers [HPDDL], also known as semiconductor lasers, are becoming more prevalent as a heat source for industrial applications. Diode laser technology has now been used in production for a number of years. Their unique beam shape, low ownership cost, high efficiency (~60%), and compact design make them an economic alternative to traditional heat technologies for heat treating and cladding of overlay operations. The benefits of using HPDL for laser surface transformation hardening and cladding are discussed.
Laser micromachining is mostly based, so far, on Q-switched laser sources. Their nanosecond pulse width often limits the accuracy and quality of laser processes by thermally initiated effects. Precision micromachining benefits from ultra short laser pulses. Up to now mostly amplified fs lasers with low repetition rates were used, with the result of low processing speed. New diode pumped solid-state picosecond lasers can also meet the demands of precise micro-machining. Their pulse duration of about 10 picoseconds provide the optimum performance e.g. for metal processing. These lasers also provide high average powers and much higher repetition rates of more then 100 kHz to maximize throughput. New potentials of picosecond lasers for the processing of different materials with high precision and increased speed will be discussed.