TITANIUM MACHINING
have mastered the process, using tools designed for titanium and other diffi cult-to-cut materials on machines that provide the required stability and torque, he said. Jan Andersson, global manager, TechTeam and market-
ing for Greenleaf Corp. (Saegertown, PA), agreed that major improvements have been made. Newer grades of titanium are still challenging. “Ten to 15 years ago, two grades of titanium—Ti-17 and Ti 6-4—were machined and not much else,” he said. “Today, more diffi cult titanium grades, such as 10-2-3 and 555.3, are being machined as titanium compo- nents are replacing those previously made from stainless. Ti- 6-4 and Ti-17 are relatively forgiving; you can go straight into the part and don’t have to think too much about toolpaths. If you do that with the new titanium alloys, you’ll see a signifi - cant reduction in tool life and an unpredictable process.”
geometries so well-engineered that we can cut hard materials like titanium or even Inconel without chipping or breaking tools.” Also, adaptive toolpaths from CAM software developers provide steady, productive cutting. “All you hear is a constant drone at a constant rpm,” said Terryberry. “It’s a beautiful sound.” Dave Campbell has also seen changes in how titanium is machined. He is president of Heartland Enterprises Ltd. (Fredericksburg, TX), a machine shop that turns large-diam- eter parts on heavy-duty lathes. “We turn a lot of titanium for aerospace applications using robust, high-torque, rigid tool- ing and a lot of coolant to dissipate the heat,” said Campbell. “We like to use top-of the-line Okuma 45s and V100s; they can take a beating and they last a long time.” What has changed is the shop being able to take deeper,
more aggressive depths of cut. “We were pretty timid when we fi rst got into titanium, but through trial and error we’ve upped our game—and the machines are higher-torque and more stable.” The shop uses custom toolholders and Campbell noted that using DE vibration bars from Sandvik Coromant’s Silent tools line provides added rigidity. Incremental changes like
Greenleaf’s TurboForm (TF) Chip Form, with high positive geometry, is effective in shearing titanium and reducing heat in the cut zone.
While still not a slam dunk, machining titanium has be-
come routine, according to Mark Terryberry, applications en- gineer, Haas Automation Inc. (Oxnard, CA). “With today’s tool coatings, we get tool life not possible before,” he said. “In the past, we would be changing end mills all the time—now we can make it through entire parts and even extend tool life or bump up surface footage and run our parts faster.” He noted that aluminum titanium nitride (AlTin) coatings
are extremely hard, extending tool life and helping dissipate heat—critical when machining Ti, a poor heat conductor. “The geniuses making these end mills have grinds so perfect and
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AdvancedManufacturing.org | February 2017
these are the key to improv- ing Ti machining, said Marc Kinnemann, manager, techni- cal center and training, Mit- subishi Materials U.S.A. Corp. (Schaumburg, IL). “You can’t be terribly effi cient by increas- ing surface speed, so cutting tool manufacturers made end
mills with as many cutting edges as possible to increase feed rate,” he said. “Machine builders realized they needed stiffer spindles in different rpm ranges, and all those changes have added up to a better process.” So much progress has been that many shops are machin- ing lights out and don’t give it a second thought, according to Mike Kerscher, national applications engineering manager for machine builder Mazak Corp. (Florence, KY). “Ten years ago, the act of cutting titanium unmanned would be practi- cally unheard of, not to mention extremely risky,” said Ker- scher. “Now we have customers machining the material lights
Photo courtesy Greenleaf
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