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moldmakingtechnology.com 21 FSS technology. However, shops that need to put greater and more frequent demands on the machine and get optimal preci- sion may opt to invest in FSS laser technology. Let's dig a bit deeper into the differences and examine the benefits of each so you can make an educated decision. Efficiency. A flash lamp powers a Nd:YAG laser. It provides something comparable to the flash from a camera, but much larger, so it offers a standard white light flash with a wave- length in the range of ultraviolet (UV) to infrared (IR). To pump the Nd:YAG crystals requires a wavelength of around 808 nanometers (nm). All other light produced by the flash lamp is absorbed as wasted radiation from other parts of the cavity and must be removed as heat by the water chiller cham- ber. Because of this limited available light spectrum and the need for the chiller, the average Nd:YAG laser has an energy efficiency level of 3 to 4 percent. In contrast, today's FSS lasers can reach efficiency levels of up to 35 percent. A FSS laser achieves this using laser diodes as its power source. These diodes produce only one specific wavelength that fits the absorption line perfectly. By harnessing the energy correctly, all the light that is produced by the diode is absorbed by the fiber and transferred to the laser light. This means that a 300-watt Nd:YAG system can have a 10-kilowatt power consumption, whereas a 300-watt FSS laser system only uses about 1,000 watts to complete the same job. This is important for shops because now even 450-watt FSS systems can be pow- ered and operated by a standard 220-volt outlet. Cooling. A Nd:YAG system uses laser crystals, electricity and a xenon flash lamp to create the beam. This process generates a large amount of heat within the machine, which requires a large external cooling unit to maintain proper machine temperature and performance. The chiller takes in the heat and releases it away from the machine and into the surrounding area, which can increase the temperature of the shop if done over sustained periods of time. The chiller also consumes significant amounts of electricity to keep the water temperature stable. Because diodes power FSS lasers in a specific wavelength that can be directly translated into laser light, they produce less extraneous heat. For example, to create 300 watts of laser power from a FSS machine requires 1 kilowatt of electricity, producing 700 watts of ambient heat that a small fan can remove. Creating the same wattage of laser power from a Nd:YAG machine requires 10 times the amount of electricity, resulting in 9700 watts of residual heat that can only be cooled with an external chiller. Mobility. The high power consumption and use of water chillers make Nd:YAG laser welders of more than 150 watts difficult to move, and so too does the pre- cision alignment of the Nd:YAG laser crystal and two resonator mirrors. Even with superior mechanics, the vibration and potential shock from transport can misalign the resonator and then require ser- vice by a laser technician. The low power consumption of FSS laser systems enable a standard 220-volt outlet power source, air cooling by small fans and a solid resonator with no mechanical adjustment. All of this makes them more mobile. Because the laser source is complete- ly integrated into the main body, the laser head is very small and machinists can easily move and adjust them to any position A FSS laser system is structurally stable, as it is powered by diodes in the optical fiber delivery system. Three main factors to consider in your decision for a laser welder are the budget, usage frequency and desire for a dedicated or mobile welding station.