It seems that with every new model of CNC lathe or mill, machine controllers get a little quicker and a whole lot smarter. Maybe they haven’t yet achieved HAL 9000 intelligence, but new controls and servosystems process data faster, enable tools to corner more quickly and simultaneously manage more axes than ever before. Some are even capable of monitoring conditions in the machine and adjusting cutting parameters accordingly. It’s like having a virtual machinist with his hand on the feed rate override.
The concept, at least, is nothing new. A 1989 white paper by the American Society of Mechanical Engineers mentioned that Bendix Corp. was researching adaptive-control (AC) optimization as early as 1962. The paper stated that formidable challenges to commercialization of AC technology still existed, including development of reliable sensors, machine tool designs that take into consideration AC requirements and development of stable AC strategies.
Many of the goals of that Reagan Administration-era paper have been met. Laser cutting machines automatically adjust gas and power outputs, EDMs regulate their own sparks and turning and other machining centers slow down or stop when cutters become dull. The pinnacle of AC technology—and something few controls are actually capable of—is the ability to increase feeds faster than programmed when conditions permit, thus autonomously increasing part output.
“There are two basic types of adaptive control technology,” said Thomas Pleuger, account manager for control manufacturer Mitsubishi Electric Automation Inc., Vernon Hills, Ill. “One is look-ahead technology, which relies on a high-gain servocontrol to achieve smooth acceleration and deceleration during changes in machine direction. And then there are adaptive control products that sense spindle load and adjust programmed feed rates up or down according to a set of predefined parameters.”
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