HAAS helps fibre optics manufacturer

HAAS helps fibre optics manufacturer...

The science of channelling light (the process is called total internal reflection) was first demonstrated in the mid-19th century however, practical applications came much later. NASA used fibre optics in the cameras it sent to the moon, but it wasn’t until the late 20th century that terrestrial TV adopted the medium. Tapered fibre optics work on the same principle of bouncing photons along a clad, glass conduit, but use clusters of fused fibres to magnify or, more typically, reduce an image for transfer applications.

Incom is the world’s leading manufacturer of commercial rigid, fused fibre optic faceplates, tapers, and microwell arrays. The company’s advanced technology supports researchers, scientists, and instrument makers in dental, medical, life science, scientific, homeland security, and defence industries.

Incom offers its customers both experience and expertise. Founded in 1971, the company has more than 200 employees, and spreads across more than 90,000 square feet in two facilities. In the beginning, with a just handful of employees, the company’s primary product was fused fibre optic faceplates for cathode ray tubes (CRTs).

Its early years were moderately successful, and its revenue graph was reliably linear. But management knew that CRT technology would eventually be replaced by LCDs, they just didn’t know when.

“In 1994, we had the opportunity to purchase a competing line of fused fibre optics from a local company called Galileo Electro-Optics,” says Anthony (Jay) Detarando, Vice President and Chief Financial Officer. “We didn’t fully realize it then, but it was very good timing our existing business was about to take a nose dive.” Like the proverb says: The afternoon knows what the morning didn’t suspect. “As part of the deal, we also acquired the formula for the fibre optic glass that we still use today.”

Galileo was one of two nearby companies that specialised in manufacturing fused fibre optics for military applications. The two companies were competing with each other for contracts the government warned would soon disappear. They did not disappear, and today continue to generate a large part of Incom’s revenue. “We also acquired the technical expertise to make 50 mm tapered fibre optics in high volume,” says Detarando. “Many of Galileo’s employees came to work here. All of a sudden, we were twice our previous size, and one of the two main government suppliers for night vision systems.”

Incom manufactures tapers from billets produced using its own hot-drawing process. Individual fibres are bunched coherently together, heated, and stretched to create the desired magnification. The more fibres in a bunch &ndash as many as 16 million per square inch &ndash the higher the resolution.

“Six or seven years ago, we looked at how we wanted to grow,” says Scott Farland, Director of Business Development. “We decided to get much better in military applications, and to find new opportunities in the life science, scientific, and medical sectors, such as X-ray.” Photographers have long since embraced the flexibility and speed of digital imaging. Now, radiographers are swapping X-ray cassettes for oversized CMOS sensors with thin, fibre optic plates (instead of lenses) providing the image transfer function. “It was making these types of larger tapers that first led us to investigate automation and CNC machine tools,” Farland explains.

The company divided its manufacturing into business units, each of which was allocated its own equipment, configured, and arranged to maximize efficiency. “We are very focused on yield,” continues Farland. “Glass is expensive, and it’s easy to make mistakes during hot-drawing and end up with damaged and useless fibres or clusters. We’ve developed our process to reduce this possibility. So when it came to automating the mechanical and machining operations, we had to make sure we kept scrap to an absolute minimum. By the time the taper gets to the machining stage, most of the cost has been incurred.”

Incom bought its first Haas CNC machine tool &ndash a used VF-2 vertical machining centre &ndash in late 2003. Since 2005, Incom has bought an average of two additional Haas machines per year, for a current total of 11, including five Mini Mills. Incom’s newest Haas is a DT-1 drill/tap centre that currently is cutting medical and dental faceplates.

In the early days of its reorganisation, Incom had very little in-house CNC machining experience, so they recruited programmer Dean Westhoff to pilot the company around the hazards of machining glass. Westhoff, in turn, was guided by Product and Process Development Engineer John Escolas.

“At the beginning, we were only machining around ten per cent of our production on Haas machines,” says Escolas, “at feedrates of around 0.200 inches a minute. It was a slow and expensive process. We were holding the part using an old traditional wax compound, and the wax would often fail and the part pop off the mount, even at these low feeds.” Incom gave Dean and John free reign on CNC machining standards. “The only advice I offered Dean was to turn off the control panel and go by sound and feel,” Escolas relates.

Westhoff and Escolas began by changing the composition of the wax to give greater shear strength. Once Dean felt confident the parts were fixed, he tweaked feedrates with the patience of a piano tuner, increasing them gradually until the Haas hit the right note.

Incom machines its glass with diamond-coated tooling, which will burn the part if there is insufficient coolant. Conventional machining uses nozzles to deliver the liquid from multiple directions, spraying the contact area. But when the tool is changed, the direction of the coolant needs to be adjusted. “To achieve the high-volume machining we had in mind meant we couldn’t adjust the coolant manually,” says Westhoff. “It just wasn’t practical.”

The answer was to submerge the parts and the tools completely. Each time a component is loaded and the operator presses cycle start, a custom-made, watertight tank mounted on the machine’s table floods until the part disappears. “It took a lot of faith,” says Escolas. “We were fine-tuning cutting operations, but we couldn’t see what was going on with the part. Sometimes, we’d drain the tank, and there would be nothing but shards of glass.” Incom now machines more than 90% of its production, and feedrates are typically 30 inches per minute. “Now that we’ve perfected it,” Escolas continues, “cutting under water produces better surface finishes, the tools last longer, and we can use coarser diamonds.”
Once Dean Westhoff and John Escolas had worked out how to make the product, it became Quality Engineer Earl Davis’s job to understand the processes. The subject of his initial study was one of Incom’s Haas Mini Mills.

“Our priority is always improving and maintaining yield,” Davis says, echoing the wisdom of his colleagues. “We aim to reduce scrap to a minimum by really understanding the machining process. We felt confident that the Haas machines were sufficiently accurate, so we introduced statistical process control techniques to measure what was causing variation.”
One feature of the Haas machines that Incom uses more frequently than most others is the Renishaw probing system. The probe allows Incom to export data off the machines that can be used to understand process parameters.

Davis chose to use the Renishaw probe data to track the outside diameter of a machined part. This gave him a consistent measurement to track the machine’s capability for tolerance. A sample was taken every 150 minutes across three shifts. “Because each Mini Mill produces 250 to 300 parts per day,” Davis explains, “this gave us a measurement about every 30 parts.”

The first series of tests revealed a process capability of .61 Cpk, equating to 35,000 ppm out-of-spec. “Not very good,” remembers Davis. “So we introduced X-bar charts to the cell &ndash so the operator could see what was happening in real-time &ndash and an out-of-control action plan, which indicates what to do when the process is going out of control.” It turned out that most variation was due to tool wear, and came immediately before and after a tool change.
“A few years back, we were achieving yields of around 84% for that part,” says Davis. “Now, we’re closer to 99%, and process capability has improved to 1.06 Cpk, equating to 750 ppm out-of-spec. The other amazing thing is that the Haas machine is only supposed to cut to 0.0002 inch, but we are regularly achieving tolerances of 0.00015 inch!”

It’s been a long and intensive learning process since Incom first acquired the know-how to compete in the tapered fibre optic sector, but the company’s engineers and managers have applied themselves in a way that even W. Edwards Deming would have approved of. “Quality cannot be inspected in,” the late quality-guru once told manufacturers. “It’s already there.” The key, of course, is knowing where to look, and Incom found it under several inches of water.