Modern Machine Shop

MAR 2018

Modern Machine Shop is focused on all aspects of metalworking technology - Providing the new product technologies; process solutions; supplier listings; business management; networking; and event information that companies need to be competitive.

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How Adaptive Control Works Caron Engineering's Tool Monitoring Adaptive Control with Multi-Process monitoring (TMAC MP) was designed to mitigate precisely the challenges described above. TMAC combines sensors and a CPU communicating with a multi-range power transducer to "learn" the optimum power load of the tool in order to adaptively control the feed rate. The premise is pretty simple. As just described, a machinist faced with hogging out a block of hard aerospace alloy will often take the conser- vative route when it comes to speed and feeds. The tool moves through the metal at a slow and constant feed rate. As it passes through more- and less-difficult cuts, the power load of the spindle drive spikes and lowers, respectively. Besides the inefficiency, at a certain point, any one of these spikes threatens catastrophic tool breakage if the user isn't careful. To prevent such conditions, TMAC connects to the CNC and overrides the feed rate for the whole cut. After monitoring spindle power in "learn mode" while the machine cuts a part with new tools, it establishes peak and optimal power load targets, and automatically adjusts the feed rate to maintain a constant load. Figure 1 demonstrates what unfolds on the TMAC MP screen during a sample cut: • The white line shows the actual cut's power load over time, measured in horse- power according to the left-side Y axis. • The purple line indicates the real-time feed adjustment. As the power load decreases through easier portions of the cut, the feed rate increases. As the tool enters tougher portions of the cut, the power load increases, and the feed rate slows down. Caron Engineering's TMAC MP is first and foremost a tool monitoring system, with sensors installed on the machine and a separate processor showing spindle and tool data. But combined with a power transducer, TMAC's strength is in its ability to override the tool's feed rate and apply adaptive control to optimize cutting, an especially useful feature for hogging difficult-to-machine aerospace alloys. Tool Monitoring for Low-rpm Cuts Modern Machine Shop 75

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