The right trace at the right time

Whenever a laser is used in an industrial setting, a safety enclosure is usually required. To eliminate the expense of setting up an expensive enclosure room for use of its MeccoMark 20-W, fiber-delivered ytterbium laser marking system, Ford and MECCO engineers developed a safety snorkel on the laser device. Proximity sensors alert the laser marking device that the product is in place for marking, and the snorkel device—with the laser inside—extends toward the product, in this case a transmission housing. The part actually acts as the last side of the enclosure, and a vacuum holds the part tightly to the cup—or snorkel—before the laser marking takes place.

You won't find this tale on the DIY cable network, but it's a true story of do-it-yourself success for Ford Motor Co.

Despite the sales struggles most North American automakers face, these companies still must move forward with plans to design and produce new models of automobiles. They can't elect to sit out and wait for the market to rebound in a solid fashion.

As a result, the automakers are committed to manufacturing, while at the same time keeping up with quality programs that have long been under way. Related to these quality efforts is Ford's companywide traceability program.

The goal of the program is to be able to trace manufacturing-related problems back to the specific batches of components and systems that might be affected. Typically, these traceability marks were done with dot-peening technology, but the old-school technology wasn't efficient enough for Ford's new-school approach to traceability.

What's Right With Lasers

The truth of the matter was the dot-peening technology was a loud pain in the ear. If it were to be used to apply traceability marks on aluminum transmission housings, the housings would become hell's bells.

"We had some testing done in our lab," said Frank Maslar, a Ford technical specialist. "It [the noise] was measuring 110 decibels or something like that. There was no way we could do that."

Stickers, with all of the correct part identification data, were a sound alternative, but they had their own problems. They were expensive and had a tendency to fall off given the less-than-perfectly-clean manufacturing environment.

That led Ford to consider laser marking. More specifically, the company elected to go with a MeccoMark 20-W, fiber-delivered ytterbium laser marking system that could be easily moved right up to the assembly line.

The laser marking system's small footprint and cost-effectiveness really made it an attractive alternative to the more traditional marking approaches. In fact, the unit was able to remain cost-effective because engineers worked together to help eliminate a large part of most laser-oriented products.

That is, of course, the large safety enclosure designed to contain any escaped laser light, which might hurt nearby manufacturing personnel. Instead of designing a room to house the laser marking operation, the engineers developed a vacuumtight enclosure to encapsulate the actual marking process.

A laser marking system can produce a 2-D data matrix mark that can contain much more information than a simple series of numbers or words.

"I'm a cheap guy. I don't want to spend money if I don't have to," Maslar said.

When a transmission housing approaches the laser marking device, a sensor activates the device. Then a cup-like device with the actual laser in it extends toward the part. A vacuum ensures a snug fit between the covering—or as Maslar calls it, a snorkel— surrounding the laser and the transmission housing, which has a surface that acts as the final wall of the light-tight enclosure. The MECCO proprietary design meets the Center for Devices and Radiological Health's definition of a Class 1 enclosure, which keeps personnel from possible exposure to laser light.

The laser marking device is also doing the job it was supposed to do—apply easy-to-read, 2-D data matrix marks on transmission housings. These two-dimensional digital codes—which can store more than 3,000 characters in a limited amount of space—contain several important traceability numbers for Ford, including a manufacturing date, a vendor code, a serial number that some Ford plants use as a time stamp, and the official Ford part number. The laser marking device can produce up to 250 characters per second, covering a space up to 5 inches by 5 inches.

Those closely intertwined with the automotive industry should know that the laser markings meet all the Automotive Industry Action Group 2-D data matrix marking requirements specified in the B-4 marking and identification standard and the B-17 direct part marking guidelines. For those outside the auto industry, they should know that the original three-month trial turned into a two-year commitment at the Ford transmission plant in Livonia, Mich.

"So, for example, on the transmission line for the last two years that it's been installed, we have processed about 250,000 parts, and I have a 100 percent read rate," Maslar said.

Making Its Mark

Ironically, the laser marking system will be used next not on an aluminum part, but on a cast-iron engine component. Ford turned to the laser marking system to streamline the process for reworking parts coming off a cylinder block manufacturing line.

When cast-iron parts were reprocessed in the past, someone had to machine off the old dot-peened traceability mark before the new one could be applied. With the laser, no one has to machine off the old mark during reprocessing. The laser applies a new traceability mark right over the original laser-marked data matrix block.

Maslar said future applications likely will center on rough aluminum parts for the same reasons it made so much sense for the aluminum transmission housings. Right now a lot of those parts are stamped with the traceability mark, which is not very easy to read.

"The nice thing about the laser is that it has a really fine mark quality," he said. "We really like that."