Cutting Tool Engineering
July 2012 / Volume 64 / Issue 7

Milling tool is strong in the pocket

By CTE Staff

When it comes to speed, the RampMill is a top performer, according to Aaron Fike, sales and marketing manager of toolmaker SwiftCARBCNC, Kent, Wash. In pocketing applications when cutting difficult-to-machine materials like titanium, Inconel and tool steel, Fike said his tool cuts faster than the competition’s. “We’ve done extensive testing with the RampMill. Apples to apples, we pocket five to 10 times faster than anyone in difficult materials.”

Even in less demanding materials, the RampMill performs well. Merrill Kincade, senior programmer at fitness equipment manufacturer Precor, Woodinville, Wash., explained how his company was able to increase production rates nearly 50 percent when machining an aluminum extrusion. “Previously, we were roughing and semifinishing a 1.574 "-dia. × 1.315 "-deep through-hole using three tools: a 1¼ " indexable-insert drill; a 1 ", 4-flute endmill; and an indexable twin cutter. One ¾ " RampMill replaced all that, and our output went from just over eight cycles per shift to 12.”

RampMill is an endmill that isn’t an endmill, according to Fike. “Take a typical milling job in Ti6Al-4V, for example,” he said. “Using a conventional endmill, ramping at an angle of more than 0.75° in titanium is not practical, whereas we ramp routinely at 7° in titanium, nearly 10 times the maximum angle of an endmill, and at higher feeds and speeds. The RampMill can helically interpolate 20 to 30 times faster than an endmill.”

RampMill has more than 1,000 patent-pending design claims, including unique geometric features, through-coolant and a proprietary coating, according to Fike. “The only thing that the RampMill and an endmill have in common is that both can do side milling,” he said.

According to Fike, the RampMill was designed for controlled radial-engagement toolpaths. “Toolpath is extremely important in high-cube machining,” he said. “When you’re pushing a tool as hard as we can with the RampMill, you have to maintain a constant load on the cutter and consistent cutter engagement throughout the toolpath, especially in the corners—you can’t slow down or you’re dead. Up until the past year or so, most CAD/CAM manufacturers didn’t have a controlled radial-engagement toolpath. But today, probably 75 to 80 percent of the CAM makers have developed new cutter paths that work great.”

rampmill.tif
Courtesy of SwiftCARBCNC

A RampMill consistently produces short chips while circular interpolating a 4140 steel workpiece at 2 diameters deep and a 260-ipm feed rate.

Anyone who’s ever listened to an endmill chomping and grinding on recut chips knows high-pressure through-coolant is a huge advantage. “You can’t recut chips in titanium and Inconel,” Fike said. “If you try, any tool will fail almost immediately. Our center coolant hole solves this problem. Toolmakers have always steered away from this in endmills because it kills the tool’s center-cutting ability, but by designing a tool that ramps rather than plunges, we’ve eliminated that limitation. As a result, tool life when pocketing goes up two to seven times.”

SwiftCarb purchased a coating chamber to apply its MDC coating to the RampMill. “We started out trying to devise a coating just for cutting titanium, but ended up with a coating that works in most workpiece materials,” Fike said. “MDC has great lubricity, excellent wear resistance and high heat resistance. The result is you can replace three different application-specific coatings with just one high-performance production coating.”

Of course, success with the RampMill isn’t foolproof. Because of the demanding toolpaths involved with constant radial engagement, it requires a responsive and rigid machine tool. “You can’t slow down or dwell in the corners. If you do, the material workhardens and no tool can survive that,” Fike said.

AV3CH.tif
Courtesy of SwiftCARBCNC

It also requires the right toolholder. “Forget about commodity endmill holders,” he said. “Try running 450 sfm in titanium with a sidelock holder and you’re not going to make it half an inch. You need a good milling chuck or a shrink-fit holder.”

One shop seeing impressive results with the RampMill in titanium is Hardy Engineering & Manufacturing, Auburn, Wash. According to Manufacturing Engineer Jeff Olberg, Hardy was able to cut cycle time in half by switching from conventional endmills to the RampMill. He said: “We machine a lift truck component from a titanium block measuring 6 "×7½ "×9 ". Our old process took 10 hours and required a number of tool changes. Now we mill the whole thing out in just 5 hours with one standard-length ½ " RampMill, and have increased tool life sixfold. It’s a great value.”

Parts manufacturing comes down to how fast a shop can get things done. “That’s what they get paid for,” Fike said. “And that’s why we developed the RampMill—to make parts faster. There’s nowhere that it doesn’t work, whether you have a 100-hp or 10-hp machine. It’s all about getting the most out of what you already have.” CTE

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