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34 MMS April 2017 mmsonline.com RAPID TRAVERSE Machining Technology in Brief the more tightly focused the beam and the more effective it is for finer cutting, Dr. Shannon says. Adjustable beam parameters. Whatever the gain medium, laser markers have gotten more powerful, he says, citing power ratings of 100 watts or more compared to only about 20 watts in the past. High-intensity, short pulses (measured in nanoseconds) are critical to actually ablating (vaporizing) metal rather than melting or merely discoloring it. However, the range of applications that any given system can ef fectively handle depends largely on how it achieves these pulses. A common means is Q switching, or the mod- ulation of the intracavity losses—the Q (quality) factor—of a laser resonator. Put simply, a variable attenuator within the resonator delays lasing and allows energy to build up before the beam is released. Dr. Shannon analogizes this affect to allowing water to accumulate in a tub before releasing the drain plug. The problem is that Q-switched lasers offer limited functionality for tuning parameters according to specif ic job requirements. That's not to say parameters can't be tuned at all, or that Q-switched lasers are ineffective for more general machining. Most users will adjust frequency (the number of pulse outputs per second, measured in Hertz). Higher frequencies yield longer-lasting, more powerful pulses. Lower frequencies yield less powerful, shorter pulses. However, pulse power and duration cannot be adjusted in isolation with a YV0 4 marker, nor with any fiber laser that relies on Q switching. More versatile systems employ direct-modulated input, in which the diode itself drives energy amplifica- tion within the resonator. This enables adjusting frequency and pulse width independently to provide sufficient cutting power without introduc- ing too much heat. This has implications for power, speed and quality, Dr. Shannon says. Wide range of motion. Many benchtop laser systems rely solely on a series of mirrors mounted on galvo motors to target the beam. There's nothing wrong with this basic configuration, he says, but systems with motorized X- and Y-axis stages offer the additional flexibility of mounting multiple parts within the workzone. Software is also an important consideration for ensuring the beam can be directed properly through the mate- rial, he adds. Dr. Shannon emphasizes that any laser marker can operate as a mini machining center to some extent—if it's used properly. Even the most ideally configured system goes only so far without suf- ficient exper tise, he says, adding that Amada Miyachi considers tips and tricks key value-add on every sale. "It's no trivial matter to figure out how to create the features you want, and to do so in the most efficient way," he says. Amada Miyachi America Inc., call 626-303-5676 or visit amadamiyachi.com. With narrower, higher-intensity beams than their multi-mode cousins, single-mode lasers are generally more effective in metalcutting applications.