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Out of Huntington Beach, California, Millen's top notch team is backed up by the latest engineering, design, analysis and CAD/CAM software. They are nationally known and respected, and have developed techniques in each specialization which builds superiority into the end result.
In Millen-designed competition vehicles, minimizing weight in racecar parts is one critical factor in winning. Weight affects handling, acceleration, braking, and total car performance. To reduce weight, parts are designed with minimum safety factors. As a result, team engineers manage life time and distance for each part individually to ensure safety and reliability.
Multiple pockets and slots are often employed to minimize component weights. And, these pockets are not simple shapes at all. Large numbers of these parts are not required, but accuracy, finish and speed of production are of the utmost importance. Many parts are machined directly instead of casting or other secondary operations, often saving time and money. But for this phase of Rod Millen production to be successful, the CNC machinist must produce a part with complex surfaces quickly and without mistakes – and much of this burden falls on Mastercam.
A look into the transfer case housing for Toyota’s Rod Millen-designed 4WD Toyota Tacoma Unlimited Class Hillclimb Vehicle gives us a close-up of how advanced CAD/CAM features enable Rod Millen machinists to accomplish the engineers’ goals. Specifically, how easily solid modeling was imported and machined with 3D rough toolpathing; how intelligent feed rate optimization kept production at maximum efficiency; and how 2D finish toolpaths made accurate, high-tolerance finishing automatic. In short, how state-of-the-art CAD/CAM software (Mastercam) helped wrangle the power of 900 horses successfully up against the competition.
CNC Programmer / Operator Nobu Okawa receives the engineer’s solid design file flawlessly into Mastercam, which Okawa says, “is powerful enough to manipulate almost any solid file and create, analyze, and correct for bad surfaces in files prior to machining. The impressive thing about Mastercam’s CAD engine is that it’s really designed for machinists. The way it’s set up and the tools it includes are streamlined, practical, and meant to create machinable models easily.”
Each transfer case housing, with its variety of pocket sizes, steps, and bosses, was machined from 18” x 10” x 2” 6061-T6 aluminum. Mr. Okawa drilled the assembly bolt holes first and says, “I started 3D machining inside first using a 3/4” end mill, roughed it, and cut the outside edges with a ½” 3-flute end mill. Then I turned the piece over and roughed the front side with the ¾” tool. I left .020” to .030” on both sides for the finish path.” Okawa chose Mastercam’s multisurface “pocket” roughing toolpath because of the complicated part features and the varying pocket depths. “That toolpath automatically avoids the radius area of each pocket – closer to the finish contour to make the finish cutting easier and faster. Mastercam’s associative toolpaths make reprogramming so much easier when engineering calls for modifications to these unique parts.”
Mastercam’s Intelligent Feed Rate Optimization links itself to the toolpath and automatically reduces feed rate anywhere cutting conditions change – in deeper pockets, for instance. “Without feed rate optimization,” Okawa says, “I would have had to use the slowest feed rate over the entire piece. This might have taken 25% longer. With our kind of production schedules, we can’t afford any extra time.”
And, Toyota Tacoma’s racing performance results validate the care taken with this and all facets of the racecar’s design and manufacture! |