One of the great efforts of wind-turbine OEMs is to take cost out their products without lowering quality. One way to do so is in manufacturing with special tools. For instance, a particular profile on a turbine hub often required several tools and machining techniques to impart required features. In previous setups, the profile was given what machinists called the Christmas tree shape, but only after several long procedures.
Tooling engineers were presented with the challenge of improving the procedure and came up with a custom cutting head capable of completing the operations in one pass. The tool was the result of careful analysis that considered the material, the profile, and the power available to the machine selected for the operation.
Another significant tool, though less wind specific, promises to trim time of many milling jobs. This face milling cutter hold eight inserts, the octagon shaped discs that do the metal removal. The manufacturer says it is a versatile, economical, and productive tool that can be used for roughing and finishing. The inserts are positioned in pockets by hardened high-strength-steel pins. This simplifies indexing the inserts. Eight flats on both side of each insert give it 16 cutting edges. The tool works well on gearbox housings.
Other areas for improvement are the difficultto- access machining areas such as large complex monolithic workpieces and deep cavities. These call for long overhang tools which present challenge such as chatter, a condition that produces shallow gouges on surfaces. One solution comes in a tool holder with passive dynamic damping. The shell-mill holder is said to offer up to three times greater dynamic rigidity than equivalent solid holders. This allows machining cavities that are over five time their diameter deep, with optimal cutting conditions.
Furthermore, the vibration damping holder is said to significantly improve the dynamic rigidity of milling assemblies. This allows higher cutting speeds with quieter operation and improved stability. These results lead to increased productivity, improved surface finish, and longer tool and spindle life than previously possible. The tool’s manufacturer claims the holder can reduce machine time by up to 50%.