Saving Energy at the Machine-Tool

It’s never been easier to monitor and conserve energy use on machining equipment.

According to the U.S. Energy Information Administration, global energy-related CO2 emissions are expected to rise from 32 billion metric tons back in 2012 to 36 billion metric tons in 2020. About 25 percent of these emissions are attributable to manufacturing. For that reason, governments, industry and universities have put a lot of effort into finding ways to conserve energy in the factory. Many manufacturers that pursue energy conservation may discover that there can be financial benefits as well—and those that don’t pursue it may find they are leaving money on the table.

A good place to start with energy saving is at the machine tool.

Taking Control
More than half of the electricity consumption in manufacturing is from machine tool use, according to U.S. Energy Information Administration statistics. Machine tool idling, unnecessary pump rotation and continuous running of peripheral equipment, for example, burn energy that, when better managed, can provide significant savings. 

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Machine tool software developers have been introducing programs to make energy management easy. For example, the Okuma America Corp. OSP software suite includes ECO suite, a package of intelligent control applications to minimize unnecessary energy expenditures: one monitors the cooling status of the spindles and automatically turns off the coolers for these spindles when cooling is complete. Another shows the power consumption of spindles, feed axes and peripheral equipment on the machine tool’s display. A third ensures that peripheral equipment such as chip conveyors and mist collectors will only run when needed, and only for the duration required. And with some minor hardware additions, a hydraulics feature provides accurate control at a very low rotation speed as pump rotation is optimized to match operating status.

Okuma is not alone in offering energy-optimizing software. Another example is the Mazak Corp.'s  MAZATROL SmoothX CNC control, which includes the SMOOTH Energy Dashboard that displays a range of power consumption metrics, including electricity charges and daily peak power. It’s specifically designed to work with ERP systems, to ensure that a facility can include the energy usage of individual machines in the overall production analysis.

And users of the Siemens Industry Inc. Sinumerik CNC can simply hit the “Ctrl” and “E” key combination on the operator panel to get a fast evaluation of the machine tool’s energy consumption and also manage energy consumption during machine downtime.

Using the “Ctrl-E Analysis” function, Sinumerik controls determine both the energy consumption of a drive system and the entire machine. They enable the user to analyze the amount of energy that goes into machining every individual workpiece as the basis for machining strategy improvements. The “Ctrl-E Profiles” function also provides a configuration platform for the management of the machine’s energy-saving modes, helping to selectively shut down specific power loads during downtimes.

Beyond the Electric Bill
What kind of savings does the use of such a package add up to? Okuma America supervisor and product specialist Brad Klippstein has a spreadsheet he keeps handy to show the energy cost savings a given user can expect: A shop running 10 MB5000H horizontal machining centers 240 days a year in Michigan, for example, can expect an annual savings of $34,565 using ECO suite. 

But the savings are greater than what one gains from reducing energy usage, he said, because when you're able to power down a piece of equipment that would otherwise be running, you are extending its life and decreasing the frequency it will need to be maintained. 
“If you’re able to cut off the use of a pump six times a day—one that would otherwise be running 24/7—you won’t need to maintenance it nearly as often. Stopping machining time for maintenance happens at a cost. That’s something people don’t always think about when they first see an eco-related function. That benefit may speak more immediately to them than their monthly electricity bill.”

The rising acceptance of Industry 4.0 or Smart Manufacturing in the U.S. will make achieving energy savings at the machine tool easier to reach. According to the American Council for an Energy-Efficient Economy, “Increased investments in Smart Manufacturing could save American manufacturers $15 billion in annual electricity cost savings by 2035.” That tantalizing number is one of the spurs to U.S. manufacturers to follow the lead of Europe and Asia and embrace Industry 4.0. As they do so, the data from—and value of—machine-centered energy-saving software will be better appreciated, Klippstein said. 

“A lot of our customers are now beginning to gather digital data from the machine and use it to improve operations,” Klippstein said. “Energy use is another useful metric that they can pull from the machine. The data is collectible and measurable and can be put to use. More customers are starting to grasp that concept. Once they do, this is something that will be of more interest to them.”