Choosing a parts-marking method depends on the application

Until a couple of years ago, the Food and Drug Administration required a unique identifier on each distinct assembly of a medical device in human- and machine-readable forms.

That rule has changed. Now, every individual component in an assembly must be marked as well. Traceability is becoming more and more prevalent, not only in the medical device sector but throughout manufacturing. In this emerging era of Big Data, every product and process becomes traceable—and, therefore, more easily improved by their makers. OEMs and job shops alike are investing in parts-marking capabilities.

They have a lot of options, from the newest, shiniest laser-marking systems to engraving tools and impact-based approaches such as dot-peen marking. Applications exist wherein each of these would be the best parts-marking method, and one might see multiple methods in a single facility.

A 2L engraving tool in the company’s spring-loaded engraving toolholder, which allows fast plunging into hard alloys. Image courtesy of 2L.

“We have large aerospace customers who have all the parts-marking technologies they could want—dot-peen, laser and cutting tools like ours,” said Lance Nelson, president of 2L Inc., Hudson, Mass. “There are reasons for them to use each one.”

Hot Technology

Aerospace is a big part of the business conducted by Beamer Laser Marking Systems, Flushing, Mich., said Brian Bittner, the company’s national sales manager. “We do a lot of aerospace and medical parts, as well as [serve] lower-mix, higher-volume areas such as automotive, where the speed of laser marking is a big advantage.” Laser marking cutting tools is another of the company’s niches—and is a high-volume area too, he noted. Along with making, selling and servicing seven series of laser-marking systems, Beamer provides marking services on a contract basis to customers that aren’t ready to purchase a system of their own.

Shining a light on an object is generally a faster process than physically cutting it with a blade or hitting it with a hammer. It would seem, therefore, that using a laser must be a faster marking method than impact marking, such as dot peen or engraving. But that isn’t necessarily true.

“Don’t get me wrong—impact marking is very fast as well,” Bittner said. Laser has other advantages, however, including its minimal effect on the part being marked. Because the beam spot size is down to 20µm and the pulse length is so short (measured in nanoseconds), there’s a negligible heat-affected zone.

The operator can simply scan a work order or bar code to have job-specific data autopopulate in a Beamer laser-marking system. Image courtesy of Beamer Laser Marking Systems.

Moreover, laser marking common materials, such as stainless steel, is done by a process called annealing. The beam heats the metal enough to draw carbon to the surface, creating a dark spot (think of burned toast) but without melting the metal or changing its dimensions. Bittner contrasts this process with the danger of stress fractures that can be introduced from impact marking and burrs from engraving systems.

Lasers are also more versatile in terms of the marks they can make. Elaborate company logos are no more difficult to transcribe than a serial number. Moreover, with the advent of fiber lasers—which are less expensive and easier to
maintain than models based on older technology—laser marking is within the reach of more shops than ever, according to Bittner.

“There are so many applications for laser marking now that, in comparison, other methods, such as dot peen, are being seen as the old, archaic way of doing things,” Bittner said. “Not that they’re ever totally going away, but much of their business has dried up since laser has come around.”

Making an Impact

Rick Pentz, vice president of the marking division at Dapra Corp., Bloomfield, Conn., partially agrees with that assessment. Dapra sells and services both dot-peen and laser-marking systems and offers contract marking services.

“Dot peen tends to be used less in applications where speed is a priority,” he said. The process was originally developed in the 1980s, specifically “to provide a permanent way to identify jet engine components while minimizing stress the processes put on the part.”