Radical Departures - Boeing Reduces Cost of NC Programming and HSM

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	With advanced high-speed machining (HSM) processes, aircraft companies are able to manufacture aircraft structural components with reduced cycle times and increased productivity. Similarly, HSM of aluminum parts offers higher metal removal rates and, therefore, potential for more profitable operations. This has been proven in the aerospace industry over the last decade, when spindle speeds in the range of 10-15,000 rpm started to be used. However, during this time, it has also been found that HSM poses a new set of problems that can be very costly. These can lead to rapid spindle failures and to scrapped parts due to chatter. The Boeing Commercial Airplane Group developed two systems a sensor-based adaptive control system and Machining Prediction Software (MPS) both of which are used to predict chatter and other process problems. These have proven to be of crucial importance for reducing cost of both NC programming and operation of HSM. MPS is used to predict chatter and other machining problems. It is, therefore, an effective aid when selecting optimal cutting concepts, cutters, feed, speed, etc. However, it has also been shown again by using MPS that prediction alone is not sufficient for reliable machining operations because of uncontrollable process parameter variations. The solution to this problem is to use MPS for optimum programming and adaptive control to provide real time, sensor-based control of the process. This keeps the machine running at its maximum capacity without risk of destroying bearings, tapers and many other parts. Large savings in machining costs are possible by using these two systems. Jan Jeppson, Associate Technical Fellow with Boeing’s Commercial Airplane Group, put it this way: When adaptive control and MPS are available, several of the NC programmer’s concerns are removed. No longer is it necessary to try to guess if an overload will occur, nor is it necessary to make several tape tryout’s to find the best feed and speed, and cut cross-sections to avoid chatter. The result is a large improvement in the productivity of the programmer and the shop. And that productivity and money saved leads to bigger profits. Copyright © 2001 - 2008 by Makino, Inc. All rights reserved.