Some of the most difficult parts for Boeing Aircraft are made not in a factory, but in a one-man machine shop located down a country lane, 23 miles south of Tacoma, Washington. Started three years ago by Bill Gilquist, owner-operator-programmer, Gilquist Tool & Machine produces complex parts for Boeing out of Inconel, titanium, 15-5 stainless steel and aircraft grade aluminum. As much as 30 percent of the production is done "lights out" while Mr. Gilquist sleeps next door.
Working in a shop about the size of a two-car garage with a single Cincinnati Machine Sabre 750 vertical CNC machining center (VMC). Mr. Gilquist has become a supplier of some 60 different parts for Boeing production aircraft. The company is sole source to Boeing for certain parts on the new 777 aircraft. He earned that confidence by pushing boundaries of the possible and destroying stereotypes about the kind of work that a one-man shop can do.
"I've been able to program and run parts that other people can't touch, for some reason," he says diplomatically. But the truth is that many times, they are the kind of parts most shops won't touch. Virtually all have complex surfaces, requiring long three-axis programming. They're machined out of difficult materials like Inconel, titanium and 15-5 stainless steel, usually hogged out from bar or billet stock.
Mr. Gilquist turns the long run times on the difficult parts to his advantage. "I get around 20 hours of machine run-time a day, between 120 and 140 hours a week. I run lights out 30 to 40 of those hours—probably five nights a week." On some part runs, particularly in Inconel where machining time can run 14 to 18 hours, he gets 95 percent spindle utilization.
He performs roughing operations on parts during the day, while tending the Sabre VMC if need be. When running smaller parts, he will set up several jobs on the table at once. This allows long run times by the Sabre, particularly on harder materials, freeing him to do other jobs.
Mr. Gilquist receives part data as an IGES file from Boeing, generated off its CATIA CAD/CAM engineering system. "I can translate that into what I need..." says Mr. Gilquist. But what he doesn't say, out of modesty, is that his expertise at three-axis machining, fully utilizing the Sabre's capabilities, is critical in that translation from art to part.
He then saves final surfacing for untended, overnight machining. "I'm only removing fifteen-thousandths of material around the whole part," he notes. "I put two or three parts on the table, program into the control the tools and tool wear values, shut the lights out, and go to bed. When the tool reaches its cycle limits, the Sabre replaces it with an alternate tool and finishes machining the part. I have confidence come morning that the parts will be cut and waiting for me. It's nice to know that I can go to bed and not come out here to find scrap parts and broken tools."
In effect, Mr. Gilquist works at home. His 30 feet by 24 feet shop—about the size of a two car garage—is only about ten steps from his house. He lives in a rural area that is beginning to see the start of residential development. Although not usually the kind of place where you find a machining operation, he finds it hard to justify the dollars per square foot cost in the typical industrial park. Besides, he says he gains an hour of productivity by eliminating travel time to and from work.
What does it take today to make it as a one-man, one-machine shop? Mr. Gilquist offers this short list: No time off; the ability to do many things at once; and, the right machine.
Sabres were not that common in the area. "I did an awful lot of shopping, looked at a lot of equipment, but decided on Milacron because of its name and reputation," says Mr. Gilquist. "When I took vocational school, we worked on old Cincinnati's—World War II machines. That told me that the Milacron machines last; they're not disposable."
On the Sabre's versatility, he says, "The Sabre takes a cut in Inconel that amazes me." He cites an example of a one-inch, six-flute roughing end mill. "I can bury that one inch wide, two inches deep in Inconel and cut it. That's a 100 percent spindle load cut. When you take a corner, it's 150 percent. It was pretty scary the first time I did that. I didn't know if I was going to push the part right out of the fixture or what. The Sabre just cut right through it. I've yet to have a spindle or an axis drive problem on these materials."
Nearly all of the parts Mr. Gilquist produces require three-axis machining. "Everything in aerospace is either on a curve or angle," he notes. "All these complex surfaces are the reason that I wanted to have a linear guideway machine. In surfacing, you can't have any stick/slip. That really shows up on your surface finish. The linear guideways on the Cincinnati's are so smooth that none of that ever shows."
Data handling is also critical to tool path accuracy, since contour machining requires the processing of many more characters per block. "I have some surfacing programs that I run at 250 ipm and I've never had a data starvation problem," stresses Mr. Gilquist.
The shop gets a mixture of work from Boeing and the Sabre's speed is especially important to Mr. Gilquist on aluminum parts. "It seems to go in cycles," he says. "Sometimes I'll have nearly all aluminum parts in the shop."
Based on extensive equipment evaluation, he believes that the Sabres deliver accuracies on contour machining "a decimal place better" than competitor machines. He says, "...performance is critical for a small shop like myself, where I don't have a lot of inspection capability or time. I have to know that what is programmed is what will be cut." For a one-man machine shop, service and support is a life-or-death issue, stresses Mr. Gilquist. "If I'm down, I'm out of business. I can't afford that. Even though I have low overhead, throughput depends on the machine running."blog comments powered by Disqus