milling for machining the larger stage fan blades that are designed for higher by-pass ratios overcomes the tendency of the blades to deform under more cutting force,” said Hyatt. “Pinch milling is available on any of our mill-turn ma- chines, preferably with the Siemens 840D control as well as the DMG machining centers. The zero-chip process is a tech- nique we use to vacuum dust and swarf through the tool and through the spindle away from the work zone when machining carbon fi ber. Zero-chip machining is available on NMV ma- chines and the NVX machines that are currently being used for production of some of the carbon-fi ber components in the wing box for the 787,” said Hyatt.
Special machining packages for heavy cutting of diffi cult- to-machine alloys have also been developed by DMG Mori Seiki. “For example, new designs for integral bladed rotors [IBR] are being used more frequently in new stages of the engines. We’re seeing tandem blisks for IBRs, where two or three stages are machined from a single piece of material. For
those applications, direct-drive of the rotary axis on the NMV and Mono Block machines is faster, more accurate with a longer service life than gear-driven rotary tables,” said Hyatt. Choosing a vertical or horizontal machine is important in terms of the fl oor space requirements and the size of the workpiece. “Typically the heavier components tend to go on the horizontals and the lighter components tend to go on the vertical machining centers,” said Hyatt. “With a heavy work- piece, it’s unattractive to be rotating an extremely massive workpiece centrifugally. You want to leave the workpiece static and rotate the spindle and bring the spindle to the workpiece. With the workpieces that are low in mass, it’s advantageous to do just the opposite. Blisks and impellers tend to go on the vertical based fi ve-axis machines,” said Hyatt .
Critical Cooling Holes Get at Production Speed For machining critical cooling air holes and shaped diffuser holes in blade and vane segments, Makino (Mason, OH) has