Making the boxes that the boxes of granola bars go into is a process that has been made more energy-efficient by design, according to Dan Aubertin, senior product manager at Pearson Packaging Systems, Spokane, Wash. Doing so also upped throughput by more than 40%.
This tale illustrates what's possible when systems are designed to be more energy-efficient. Pulling off such an improvement could require using the latest technology, which can enable sleep or other efficiency-boosting modes. Solutions might demand system-wide changes, such as swapping out one mode of motion for another. A final design-related area that could be a part of the answer is automation. That can allow savings to be realized without impacting production.
Airing Savings Out
In the case of Pearson Packaging, all of these techniques were used or are being considered for use. The company designs, produces, integrates and services an array of secondary packaging automation solutions. A system can take materials such as cardboard flats, fold and erect them into rectangular shapes, and seal them to create a container. Into these boxes are placed food, beverages and other types of goods for shipment from manufacturers to warehouses or retailers.
Traditionally, the motions required to fabricate these secondary containers have been handled by pneumatics, with air-powered cylinders using force to shape and manipulate cardboard as needed to erect the boxes. However, Aubertin thinks this is not the most efficient way to do the job, in part because of flaws in the basic system design.
"Compressed air goes through several energy conversions," Aubertin says, listing these as electrical energy driving pumps to compress air, which then drives pneumatics. "You have three energy conversions. Every one of those is inefficient."
The total efficiency of multiple energy conversions to produce compressed air is somewhere south of 20% and can be much less. In contrast, servomotors come in at around 80% efficient, Aubertin says. He adds that most pneumatic motion can be replaced with servomotor-driven movement, a design change that by itself can boost efficiency.
But servomotors allow even more improvements to be done. For one thing, they have closed-loop feedback. That enables acceleration and deceleration profiles to be tuned, cutting even more energy waste. To that can be added sleep modes, which are times when the system is idle and consuming little energy, but is ready to quickly resume processing product.
Pearson Packaging redesigned its CE50 family of case erectors (Figure 1) with the new design using servomotors rather than pneumatics. That reduced air consumption to nearly nothing, a key customer request. The changeover also upped throughput from 35 to 50 cases per minute, Aubertin says.
An important feature to design in is the capability to put a machine in the right state.
"It's really around the ability to go into operational and non-operational energy management. That's the aspect of taking it beyond just efficient motors and to making sure I'm only on when I need to be on, and I'm off when I don't have to be on," says Phil Kaufman, business manager for industrial energy management at Rockwell Automation.