LASER SERVES MEN

One of the main characteristics of laser radiation is  its intensity. From the invention of the laser in the 1950's it was recognized that intense laser beams might be a good way to deposit large quantities of energy in materials for manufacturing purposes. That potentiality has now become a mature technology. Over the past decade high-power lasers have been used in many manufacturing processes: the welding of automobile parts, electronic devices and medical instruments; the heat-treating of automobile and airplane parts to improve their surface properties; the cutting of sheet metal in the punch and die industry, and the  drilling of small cooling holes (007 to 05 inch) in airplane parts. In all these operations laser systems have made production lines more efficient and reduced costs.
In manufacturing lasers serve basically as devices capable of applying an extremely high flux of energy to the surface of a workpiece. In this role they have significant advantages over such conventional heat sources as flames, torches, electric arcs and plasma jets. Among those advantages are a product of higher quality (in terms of better performance and a reduction in the number of parts that have to be reworked or scrapped); reduced outlays for materials, labor and processing; high productivity (with resulting reductions in floor space and depreciation costs); a better working environment, and the flexibility and versatility of the laser and the production system based on it.
It is becoming common to speak of two classes of high-power lasers, light and heavy. The classification depends mainly on the power. The light lasers operate in the range from a few tens of watts to a few hundred. They serve in such work as cutting and drilling ceramic substrates in the electronics industry, drilling rubies in the watchmaking industry and cutting not only metal but also cloth, plastics and wood in a variety of other industries. Many of the lasers are fairly small solid-state devices: ruby laser (with a wavelength of 69 micrometers), neodymium-doped glass lasers and neodymium-doped yttrium aluminium garnet lasers (both with a wavelength of 1.06 micrometers in the. infrared). These wavelengths couple well with most metals, making it possible to apply them in welding, drilling, cutting and heat-treating.
The light class of lasers also includes certain gas lasers (argon and carbon dioxide), which are operated mostly in the continuous-wave mode. The beam emitted by a gas laser has almost total collimation, meaning that it shows little of the divergence that characterized the beam of, say, a flashlight. Hence the beam can be concentrated in a small spot (ranging-in size from micrometers to a fraction of a millimeter), and it delivers power of great intensity. These characteristics are important, particularly in wording by the deep-penetration process.
The heavy lasers range in power from a few kilowatts to a few tens of kilowatts. The heavy lasers in manifacturing serve in heavy-duty processing such as the welding of pipelines, the welding of automobile parts and the heattreting of the surface of, such parts as crankshafts and the cinder walls of large diesel engines. The treatment hardens the surface,  increasing the resistance of the part to wear. Most of the heavy-duty lasers are carbon dioxide lasers operating in the continuous mode.
The high flux of electromagnetic energy appied to the surface of the workpiece by a laser is absorbed in an outer layer about 10 nanometers (0.000001 millimeter) thick. In that thin layer a heat source of very great intensity is thereby established. An advantage of the laser is that the heat energy is maintained and made to work in the region where the work has to be done. For this reason the energy efficiency is high, ranging from 10 to 1,000 times higher than it is in conventional systems that heat proportionately larger volumes of the workpiece. Laser systems thus achieve notably fast processing times and unique processing properties.
Another important advantage of the laser is that it does not damage parts, since it delivers heat in less time than a conventational source because of the high power density of the beam. Therefore the heat has no time to flow into the part. Conventional sources heat far more of the workpiece than is necessary, giving rise to thermally induced distortion , cracks or stresses that can damage the part, making it necessary to rework or scrap it or impairing its performance. The economic implications are obvious for costly semifinished parts such as gears whose teeth need to be hardened. Jet-engine turbine blades in which cooling holes must be drilled and engine blocks whose cylinder bores need to be hardened on the inside .
All these advantages result from the extremely high power density of the laser beam. Certain other advantages make the laser beam a highly flexible tool and explain why lasers can often be employed with good results even at the level of power obtainable from conventional sources. The beam has no mass and can be easily moved and controlled with short response times. It is easily accommodated in automatic processes. It acts from a distance, eliminating or reducing problems of mechanical interference. By the same token it does not generate mechanical responses, so that the workpiece does not vibrate and does not need to be clamped. Finally, laser technology makes for clean and fast processing that is compatible with work stations along production lines. As a result the technology has significant implications for the logistics and compactness of the production system.
These advantages become apparent in the specific things laser can accomplish in manufacturing, such as drilling; deburring, cutting, welding and heat-treating. The present achievements in laser technology are impressive but they represent only a beginning of the contributions laser systems can be expected to make to industry.