AFG was incorporated in 1993, the year fresh-out-of-college owner Adam Grizzle first laid hands on CNC equipment and CAD/CAM software in the business environment. Seven years later, in 2000, AFG became a Bronze Level Certified Supplier to Boeing.
AFG had eight 3-axis mills, and in 1999, purchased a 5-axis machining center as well as a waterjet machine. All of them were programmed using Mastercam from CNC Software. AFG used this same software to model the first part it aggressively pursued following the purchase of its 5-axis machine, an aluminum window frame for the U.S. Air Force/Boeing C-17 cargo plane. “Because of our Mastercam-driven 5-axis capabilities and our high-quality/on-time record, Boeing asked us to bid for the window project,” says Adam Grizzle, President of AFG.
The aluminum window frame part was roughed with waterjet and finished through 5-axis milling. Where large plate stock was used, the waterjet process allowed cut-out blanks to be nested for maximum material efficiency. Nesting the part let the shop get one extra piece out of the plate. 5-axis machining was a must. The frame had to conform not only to the semi-cylindrical curve of the aircraft’s fuselage, but also had to accommodate the fore-to-aft sweep.
Even so, the geometry existed only in blueprint form. Although it reached production in the 1990s, the plane was being designed as early as the ’60s. Translating all of its part designs into CAD would not have been cost-effective for Boeing, so Mr. Grizzle worked from the print to create the 3D model of the part for CNC programming.
The frame was machined from 2.5-inch thick 7050-T7651 aluminum plate. While the shop formerly used standard-size plate for the part, it now machines the part out of plate cut to size so it can deliver the part on a JIT basis.
AFG bought its 5-axis machining center the same year it bought the waterjet machine. Mastercam generates toolpaths for both machines. “If we had done the roughing on the 5-axis machine, we’d have added an hour to each piece,” says Mr. Grizzle. Using the machining center alone also would have wasted material, with the material that might otherwise deliver a fifth piece ending up in a pile of chips. “That means the overall material cost per piece would be higher,” he says. “In bidding situations, nested waterjet roughing is part of our competitive edge.”
Most users don’t think of Mastercam as a system for programming waterjets. A waterjet machine usually comes with its own programming system. However, AFG prefers to perform all of its programming off-line, using one system for all of its machines.
This 1-inch thick titanium part is cut to its final dimensions and surface quality using one pass on the waterjet machine. “We treat the stream diameter just as we would a small diameter cutter,” Mr. Grizzle says. A 0.040-inch nozzle becomes a 0.040-inch end mill. “Also, we can pierce holes using the software’s drill cycles and cut contours using 2D contour toolpaths. We even incorporated the automatic slowdowns for corners and arcs into the Mastercam post.” On material up to 1-inch thick, the waterjet machine can give AFG the surface quality it needs for a finish cut, even in titanium. These finish-cut parts in particular argue for programming in Mastercam. One of the reasons the shop chose Mastercam is because the toolpaths are associative. When a part model changes, the toolpaths change automatically. This is an important advantage to AFG because customers often revise their part files. By using Mastercam for waterjet cutting, the shop extends this same benefit to parts that rely on waterjet for their critical machining passes. Thanks to associativity, when the customer makes a change, the path of a milling cutter or a waterjet nozzle can change along with it.
Mastercam was the major tool of AFG’s business growth and innovation. “It’s Mastercam that converts our dreams into practical reality. The program has kept pace with us every step along the way, and neither AFG nor Mastercam shows any sign of slowing down,” notes Grizzle. AFG still brags about how their team and Mastercam met Boeing’s tolerances after only one trial run, without a customer-supplied CAD file. |