rosion and all is well—and then some new variable is introduced,” Hoult said. “In one case the passiv- ation bath conditions changed, leading to a reduc- tion in the corrosion resistance of the laser marks— and flaking occurred.” Boyle at Amada Miyachi America is familiar
with this challenge as well. “Recently we’ve been developing passivation-resistant marks with our fiber laser markers. It’s a newer, very sensitive technique,” he said. “We’ll test the mark with a bath of nitric acid that cleans off all of the germs and debris on the part, and see that the mark survives intact. It’s a very aggressive test because the acid is basically eating away at the metal at some levels. We’ve proven that we can keep the mark on and now we’re implement- ing the technique at a couple of customer sites. It’s a recent development.”
Fiber Laser Advantages The industry-wide acceptance of the fiber laser
goes beyond its having a lower price point. It has numerous advantages over earlier systems such as CO2
and YAG (yttrium aluminum garnet) sourced lasers because a lot of complexities have been removed. YAG lasers, for example, used to be driven with a flash lamp in order to get the high-intensity light needed to get the energy propagated through the YAG crystal. Flash lamps were water-cooled, required a lot of service, and were very expensive, explained Epilog’s Henry. Enter fiber. “Fiber lasers were born out of fiber optics use in the communications industry. Some very smart scientists and engineers discovered that they could dope these optical cables with different rare elements and get different wavelengths of light to propagate through and off of them. Instead of using flash lamp light, they use diode light,” Henry said. “The fiber lasers are air-cooled—you don’t need a watercooling device; they’re very compact, so they’re very easy to integrate into our systems; and they’re incredibly robust. They just work.” IPG’s Hoult added, “To say that fiber lasers have turned the industry upside down—that wouldn’t be overstating it. IPG introduced the first nanosecond- pulsed low-power laser for marking. And I think now everybody who manufactures laser marking systems has a fiber laser version in their inventory. “The main reason people like the fiber laser—and I’ve heard this time and again—is we ship them out
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to the customer, they plug them in, clamp up the op- tic, push the button, and it works,” Hoult continued. Fiber lasers are also simpler overall. “With fiber laser, there’s no free-space optics
anywhere in the device—no flash lamp. Your energy source, a diode laser, is fiber-coupled. Instead of a bunch of optic components arranged and tweaked, you simply have to splice fibers together. That means the whole thing is far more rugged and maintenance- free. The diodes last for many tens of thousands of hours. The diodes we use are called single-emitter diodes—they’re pretty much telecom diodes on steroids, with a lifetime in the six-figure range,” he said, noting that IPG makes “all our own diodes and all our own fibers.”
Improving the System While using diode-powered fiber lasers to anneal or ‘dark-mark’ medical metals is a mature technology in many ways, the providers of these systems are active in finding ways to make improvements for their customers. Schmidt Marking Systems, for example, offers
the Alpha laser system enclosure—a cabinet with a 22” (559-mm) wide pneumatic stainless steel door, according to Schmidt’s Dave Noonan. The enclosure has a powered Z-axis for automatic height variance and a removable side panel for access to the laser head and lens. It can be equipped with rotary de- vices, vision systems or part feeders and can be fully customized for larger part configurations. “We do custom cabinets and custom automation
as well,” Noonan said. “One customer recently need- ed us to make an enclosure that was large enough to hold a hospital bed. The most requested bit of auto- mation we’re asked for is a door that opens automati- cally when the marking cycle is done so the operator doesn’t have to wonder if the process is finished. It also alleviates repetitive motion concerns.” At Amada Miyachi America, they’ve moved from
working in two dimensions to three. “The basic configuration has always been a 2D marking field. Now, as technology has improved, we’re able to look at multiple levels, incorporating motion with that, marking around curved surfaces,” Boyle said. “Let’s use a trocar as an example.” The trocar is a hollow rod that is used in surger- ies, with laser-marked guidelines that show how far the surgeons are sticking this rod into the patient,
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