Published 9/15/2011

Power Sensing’s Power

Linking power usage data to machine activities is a critical first step toward sustainable manufacturing.

Mark Albert

Editor Emeritus, Modern Machine Shop

During my research for this article about machine monitoring, I discovered that TechSolve is working on an interesting approach to using power sensors for monitoring the energy consumed by machine tools in its testing laboratory. This approach has surprising implications for our concepts of productivity and cost efficiency.

According to TechSolve’s Ron Pieper, the lab simply attached a commercially available power sensor to each machine’s electrical supply. The sensor itself measures electrical power consumption and has a standard Ethernet interface to transfer data over a shop’s network. In this case, however, TechSolve developed an MTConnect adapter software program to read the data, analyze it and route it to an MTConnect-based agent. This agent, in turn, converts the data into MTConnect-compliant XML format and feeds it to software applications that further analyze and present the data.

Ron explains that having power-usage numbers in a data stream for analysis leads to three important possibilities. For one, when monitoring a modern CNC machine, it is possible to determine exactly how much energy is consumed to produce a finished workpiece, feature by feature. In one study, the firm found that an older, slower machine used significantly less energy than a newer, faster machine to make the same part. In some cases, the older machine would actually be the more cost-effective choice for such parts. Likewise, by correlating power data with G-code commands, it is possible to compare the energy efficiency of certain cutting tools in specific machining operations. Alternate toolpath strategies can also be compared on this basis. “The differences in energy costs will change how shops make decisions about part processing,” Ron predicts.

Another possibility involves power sensing on legacy machines that have limited control capability. It is easy to link power usage to machine activity. This means that data from the power sensor can reliably indicate when the machine is cycling or doing other identifiable, power-consuming tasks. An obvious use for this data is machine monitoring. In fact, this is precisely how shops will eventually get every machine on the floor connected to a machine-monitoring system, Ron tells me.

Finally, sensors can be applied to many other kinds of shop equipment. For example, TechSolve has installed power sensors on its air compressor system and is finding ways to conserve energy by detecting leaks, reducing usage and powering down during off hours. Ron says the same technology can be applied to central coolant systems, chip conveyors and separators, chillers, pallet systems, EDM water deionizers and more. Of course, attaching credible cost figures to these operations will startle many shop managers, who may be concentrating too much on reducing cycle time as the main strategy. “I’m sure energy consumption will soon become an important factor in almost every decision that shops have to make,” Ron concludes.