Everyone agrees: titanium use is on the rise. With much of the world’s airliner fleet showing its first touch of grey, aircraft manufacturers are fielding orders for new planes to replace their aging fleets. To meet competitive pressure and an unspoken mandate for greener air travel, these planes must be fast and fuel-efficient. This makes titanium the material of choice for many aircraft parts and an increasing number of structural components.
Titanium shares many of the same attributes as other heat resistant superalloys (HRSA). But where most of these are strong and heavy like an Olympic weightlifter, titanium is a gymnast, lightweight and flexible. They all have one thing in common, though—they’re a real bear to machine. Because of this, cutting tool manufacturers are stepping up with super tough carbide grades and high-tech coatings designed to slice through this arduous alloy with relative ease.
Into the shredder
Tom Hagan, milling product manager for cutting tool manufacturer Iscar Tools Inc., Oakville, ON, recommends tools with a sharp edge and tough substrate for titanium machining. Because of the high heat generated during machining, he explains, thermal cracking and edge chipping are two of the primary failure modes with this material, making good coolant flow essential. Also, a positive rake insert with light edge preparation and a TiAln or TiCn coating is your best bet for success.
One challenge with titanium machining is chip control. Iscar has developed a series of specialty inserts, of which the roughing version carries a serrated cutting edge that makes workpiece penetration easier. “The P290 cutter looks like a high speed steel roughing tool,” says Hagan. “It generates very short, manageable chips, making it ideal for machining very deep cavities. Also, the cutter itself tends to dampen vibrations, making it effective at reducing chatter even at very long overhang positions.”
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