Green Is No Gamble

April 10, 2012
It Can Be a Sure Thing to Develop Sustainable Machines and Production Lines That Will Improve Your Bottom Line
About the Author

Jim Montague is the executive editor for Control. Email him at [email protected].

Worried about blowing your dough on building greener machines and more-sustainable production lines? Don't be. You can't lose.

Of course, it's still vital to be careful and pragmatic in your approach to designing, building and implementing machines that use less power, process more-sustainable raw materials, and produce greener products. In the context of this article, green and sustainability mean any device, material or product that requires less energy, consumes fewer resources, and enables operators and end users to do the same. Then, if you can add sustainability to the usual goals of speed, efficiency, simplicity, safety and security, it becomes just another required design element and specified operating parameter — and one that can generate substantial savings for users and added revenue for builders.

"The message from our customers is, 'We want to use less material and less energy,'" says Mike Weaver, president and co-CEO at Standard-Knapp in Portland, Conn. "All the water bottles that our machinery works with started out at 18 g of plastic, but now they're down to about 12 g. This has a positive impact on sustainability, but they're less substantial, and this 'lightweighting' of typical PET bottles creates a ripple effect on downstream bottling and packaging operations. These lightweight bottles are far less tolerant of the line pressure created when the conveyors on tray packers and loaders, case packers, shrink wrappers and bottle packers decrease speed to collect and organize them for packaging, and so they can be distorted or damaged and cause processing problems." It was clear that Standard-Knapp had to reduce and balance the line pressures on its lighter bottles.

Stand Out With Sustainability
Similarly, the commercial development team at Paper Converting Machine Co. in Green Bay, Wis., saw going green as a way to differentiate its machines from their competition. A division of Barry-Wehmiller, PCMC makes wide and narrow printers for rewind lines for flexible packaging, tissue and wet wipes packaging, and other equipment. So the team sought to increase sustainability along with the efficiency of its flagship Fusion flexographic, wide-width printing machine, which is the latest generation of the central impression (CI) presses it has built for 20–30 years. Because a machine can be built greener as well as run greener, PCMC redesigned its CI press, so its 18-month-old Fusion would have 46% fewer parts by combining castings and using frameless servo motors (Figure 1).

Drier, Faster With Less Power
Figure 1: PCMC's Fusion flexographic printing machine was the result of a redesign project that enables it to be built from 47% fewer parts, and implement a compressed-air system that dries ink faster, vents half as much exhaust air, and uses its own compression process to aid air heating and save on cooling the compressor.

In addition, instead of using a traditional forced-air, ink-drying section, the team implemented PCMC's FleXtreme compressed-air drying method. Compressed-air drying is more efficient than forced air because its speed and turbulence break the boundary layer on individual ink droplets, drying them faster by overcoming the "skin effect" associated with forced-air systems.

Choosing compressed air might seem counterintuitive because it usually requires more energy, and so it's viewed as a less-sustainable approach. However, FleXtreme and its earlier, patented eXtreme method use only 20 psi compressed air, not the more costly 60–80 psi air used in most tools and factories.

As a result, FleXtreme's exhaust volume is only 4,000 cfm, so it uses far less energy than the 7,500 cfm exhaust from a typical CI press's forced-air system. In addition, while eXtreme runs its compressed air over a heating element and onto its web, FleXtreme also uses heat from the compression process itself to heat the dryer's air, which saves both air heating costs and compressor cooling expenses.

"We OEMs usually take the most recent machine we've sold, use it as the closest reference, and then add whatever new brackets or components are needed for the new specified concept," says Rodney Pennings, PCMC's product line engineering leader for printing. "However, we often don't take enough time to really clean up our designs. So, to avoid risk, we just add bigger motors, and this can waste a lot of energy. However, with Fusion, we took the time to evaluate each part. For each one, we asked, 'Does it add value?' If it did, we kept it. If not, we got rid of it. And if it didn't add value but was still necessary, then we tried to keep it to a minimum." This was a time-consuming process, but more than worthwhile in the long run.

Improving the Odds
Perhaps the best way to make sure a machine sustainability project will be a sure winner is for its builders to open their minds to what going green really means and what it can accomplish. It certainly starts with increasing efficiency and saving energy on individual machines, but that's only the beginning. Next, green thinking spreads quickly to designing machines that can process more sustainable raw materials and produce greener end products, which in turn involves larger sections of production lines and whole facilities, supply chains and communities.

This is similar to quality guru W. Edwards Deming's principles that go beyond trying to stop defects from reaching customers by inspection and sorting them out, instead finding their root causes and eliminating them. "Likewise, while it's important to comply with environmental rules for treating waste and limiting pollution, it's better to come up with a solution that prevents waste from becoming pollution in the first place," says Professor John Sutherland, head of the Environmental and Ecological Engineering Dept. at Purdue University. In the early 1990s, 15–18% of machining production costs were for cutting fluids because people thought they had to use them. However, the development of minimum-quantity lubrication (MQL) methods in the past 20 years means far less is used now."

Christopher Zei, vice president of the global OEM industry group at Rockwell Automation, adds, "Green is not a fad or a cost. Green is a best practice and a discipline. Green means savings for machine builders and their users by finally getting the right-sized motor on their machine and saving on power. For example, one of our customers had 15–18 motors on his machine, and they were all oversized. So adopting a sustainable procedure helped him wring a lot of capital costs out of his machine."

Tender, Loving Packaging and Handling
Not surprisingly, many pioneers of the sustainable machine building movement serve packaging and related users, who always want to improve energy efficiency, but also strive to use less material in their containers to reduce the environmental impact and save on material costs.

To solve its line-pressure problem, Standard-Knapp's engineers developed Zero-Gap II Infeed for continuous, low-pressure conveying. This method ensures balanced lines and resists jams by using electronic population sensors to monitor bottles accumulating in low-pressure areas, and then signal the conveyor to increase speed, maintain balance, and let the bottles enter their lanes with little pressure and no gaps. Likewise, to cushion the blow of lightweight bottles dropping to cases and to avoid leaks, Standard-Knapp devised its Soft Catch method, which also handles bottles more gently and reduces shock energy by 80% compared with regular drop packers. In addition, Standard-Knapp is using a U-board to reduce its corrugated material and glue, and replaced the metal chain in its heat-train tunnels with a plastic conveyor belt to conserve heat and reduce energy costs.

"To some extent, these technological breakthroughs sell themselves," Weaver says. "They not only help companies become greener, but they generate cost reductions in materials, labor and energy without sacrificing quality. Being sustainable is a worthwhile pursuit by itself, but if it costs a company an arm and a leg to get there, it makes the effort far less attractive and less achievable. Our goal is to help customers attain sustainability while justifying payback on their investment."

Similarly, beck packautomaten near Stuttgart in Frickenhausen, Germany, reports it's making thrifty use of power and film in its SXJ mobil packaging machine (Figure 2). Its "beck-ecofficiency" program seeks to process thin films into tightly enclosed, reduced-consumption packaging, as well as reducing parts that wear out, compressed air use, setup times and required maintenance.

Precise Film With Servos
Figure 2: Beck packautomaten's SXJ mobil migrated from pneumatics to servo motors and drives, and can achieve 120 cycles per minute, using two rolls of film to seal its packages more precisely on four sides.

To help it use less compressed air, beck worked with Lenze to migrate the hoist drive of SXJ's seal bar from pneumatics to a synchronous servo motor, which is directly mounted on a shaft-mounted, helical gearbox. Because its machine uses two rolls of film, beck's packages can be sealed more precisely on four sides, which is especially useful for handling stacks of printed material or clothing with minimal film.

To enable closed-loop control, beck built the vertical welding bar drive with a Lenze servo inverter, and its L-force platform makes sure the machine runs horizontally in sync with SXJ's overall production speed. Because the welding bar constantly resynchronizes itself with the speed of the packaging material, the edges are continually joined together within the machine's material flow. SXJ's control system was created using L-force Engineer software. To coordinate its axes, the frequency and servo inverters use CAN bus, and communication with higher-level controls occurs via Profibus.

"We're achieving 120 cycles per minute, and we've integrated the entire feed coordinating system into SXJ without add-on modules by implementing its available space more efficiently, and also by integrating the control cabinet into the machine frame," explains Julia Deharde, beck's control and marketing manager. "By making the packaging process more efficient for our customers, we boost their competitiveness, and simultaneously reduce the consumption of energy and raw materials."

Factory-Wide Sustainability
Once you begin to get a handle on making individual machines and lines more sustainable, this leads to looking at whole facilities to see if similar gains are possible across all equipment and systems.

To improve sustainability at several plants in Europe, Volkswagen Group and its Audi division in Wolfsburg, Germany, cooperate with several partners to optimize compressed-air use in pneumatic systems on various machines and production lines. This effort is part of VW's membership in the Green Car Body Technologies (GCBT) alliance with Festo, Boge and the Fraunhofer Institute for Machine Tools and Forming Technology (IWU). GCBT's collective goal is to save up to 50% of the energy used during the automotive production process.

So far, the partners have surveyed and measured many of VW's body-assembly production systems, and identified parameters for increasing energy efficiency via better leak prevention, reduction in volume due to shorter hoses, lower pressure levels and optimal drive configurations. Presently, compressed air is used in more than 350 pneumatic actuators in VW's loading and unloading stations, robots with

"Being sustainable is a worthwhile pursuit by itself, but if it costs a company an arm and a leg to get there, it makes the effort far less attractive and less achievable. Our goal is to help customers attain sustainability while justifying payback on their investment."

handling and processing functions, and encapsulated laser welding stations. Festo's condition-monitoring systems permanently check consumption and deviations to identify and record leaks or other problems. In addition, VW's automated controls manage conventional or servo-pneumatic welding tongs, grippers, toggle-lever clamps and pin-pulling cylinders. The survey revealed that more of VW's body-assembly equipment, especially welding tongs, are moving to servo-pneumatics because they're easier to control and allow rapid electrode positioning, which reduces cycle time and helps the robots work around obstacles.

"We were lacking transparent consumption data that also can be applied in relation to acquisition, operating and maintenance costs, and enable us to make comprehensive assessments for automation solutions according to total cost of ownership (TCO) criteria during production," explains VW staffer Thomas Rommel. "We need to know how to realize efficiency pragmatically."

As a result, Festo is implementing a planning-support tool at VW for simple energy-consumption estimates at system level and dynamic simulation at component level. This tool enables primary energy consumers at the factories to be identified at the push of a button, so users can immediately and more-efficiently derive requirements for compressed-air generation and distribution. Consequently, operators will be able to compare which robots, clamping devices and welding tongs are more energy-efficient for various tasks over different time periods, and then decide which is more economical to use and has better TCO in the long run.

"Sometimes, real sustainability means going back to the philosophy of how a machine or production line was built, and exploring what changes are more appropriate and efficient," says Frank Latino, Festo USA's product manager for valve terminals and electronics. "We're seeing a lot more acceptance and willingness to do this lately."

Deep Green Production
Once the individual machine, its extended production line, raw materials and end products, and facility have been made more sustainable, where else can this concept spread? The next logical step is to turn around, and make green its own end product and industry.

In this case, MBA Polymers in Richmond, Calif., combined three types of plastic recycling into one 25- to 30-step plant, which turns shredder residue, previously too hard to recycle, into practically new plastic pellets (Figure 3). This residue is mostly the byproducts of simpler recycling efforts, and so it contains the shredded remains of everything from refrigerators to PCs to cars, including their plastic, metal, cloth, glass, rubber, foam, wood, paper and other substances.

Superfine Sorting
Figure 3: MBA Polymers' three-stage plant carries out 25–30 processes to grind, sort and wash shredder residue plastic into different grades, types and colors, and then compounds, melts, extrudes and cuts it into made-to-order pellets. To improve its own sustainability, the plant's engineers have implemented multivariable drives, but they've also researched and optimized its sorting methods, heat treating temperatures, and even the material properties of its grinding blades to improve the efficiency and sustainability of their applications.

The first plant section grinds the residue down to about 6 mm pieces, and uses several methods that sometimes are repeated to separate as much of the different materials as possible, including size and air classification techniques used in food processing. Although it builds many of its own machines to do these jobs, MBA Polymers also buys some commercial machines, and adapts them to meet its requirements.

The second plant section washes the plastics, and further separates them by type, grade and color. "This step is where we had to get creative, and use some mineral mining and processing methods," says Mike Biddle, MBA Polymers' president and founder. "We've learned to exploit small physical, molecular manifestation differences in the plastic grades — the reasons why they don't like to be combined — and use these differences as a way to separate them."

Finally, the third section takes single type, grade and color, compounds them into made-to-order grades such as ABS, HIPS, polypropylene, filled and unfilled polyethylene and others, and then melts and extrudes them into strands that are cut into pellets.

To make its own processes more sustainable, MBA Polymers implemented a variety of multivariable drives and motors in its machines and lines, optimized temperatures applied during grinding and compounding, and even researched the materials used in its blades to find a happy medium between hardness and durability, Biddle says. Both its proprietary and adapted-COTS machines are monitored by about 200 I/O points that check temperatures, amperage and voltage levels, conveyor motors, auger speeds and other operating parameters, and they and the rest of the plant are managed by PLCs from Rockwell Automation. "We have I/O points and controls for each unit carrying out the 25–30 steps in our recycling process," Biddle says.

As a result, its initial, longstanding plant in Richmond serves as a pilot and research facility, and MBA Polymers has three other full-size plants running in Austria, China and the U.K. The first two can process 94 million pounds of shredder residue per year, and the U.K. plant is designed to handle twice as much. Of the total shredder residue input, 50–60% is recycled into usable plastic product, but MBA Polymers also produces a significant amount of metals and other secondary products that it can sell, as well as some mixed plastics than can't be separated but can still be used in plastic lumber and other low-end products. The remaining wood, rubber and foam are disposed of as solid waste.

"Our processes were manual when we started development 15 years ago, but we mixed in PLCs over time, so when our plants in Austria and China opened in 2006, they were fully PLC-controlled," Biddle adds. "In the future, we'll likely monitor these facilities remotely from California. We'll probably add more PLCs to manage our separation process more closely by taking in more measurements via more I/O points."

Instead of turning out pellets, Polyflow in Akron, Ohio, has developed a practical and cost-effective pyrolysis process, which basically heats dirty waste plastic in a reaction vessel until it breaks down into a fluid similar to crude oil that can be refined into fuels. Though pyrolysis has been possible for decades, Polyflow says it's only been a few years since it's been possible to tweak it well enough to handle multi-stream plastic sources. As a result, Polyflow is working with integrator South Shore Controls in Perry, Ohio, to scale up to an 8½x60 ft reactor cylinder that will continuously process 2.5 tons per hour. The plastic waste input will result in 70% liquid product, 13% char and 17% non-condensable gas, which can help run the cylinder. Also, Polyflow's process will need 1.7 million BTUs to operate, but the liquid produced reportedly will be able to produce about 27 million BTUs.

Quality Time to Grow Green
Whether you're just beginning to add more efficient motors or you've gone green throughout your facility and supply chain, becoming a more sustainable organization takes time. It took PCMC's team six to eight months to evaluate Fusion's five main sections, for example, and Pennings reports they found that chunks of its machine were over-designed compared with required performance. "To better update what had been tacked-on before, we visited users to examine existing machines to check actual torque readings and loads on motors, and more accurately update our designs," he explains. "It's unusual to be able to take the time and go to the level that we did before even making a sale."

Consequently, Pennings adds, Fusion also has better tension control of its web thanks to low-friction bearings in its rollers and more precise drive controls, which have improved its ink mileage by 10–15%. It employs Indramat servo motors and drives from Bosch Rexroth, and Kinetix drives, Point I/O components and ControlLogix software from Rockwell. Because of Fusion's simpler design and fewer parts, it reduced I/O points from 750 to about 500, networked on EtherNet/IP.

Also, the team further improved Fusion's ink efficiency by adding a force-loaded doctor chamber for removing excess ink from its rollers. Unlike traditional, manual doctor chambers with blades that are often set too tight and wear out too quickly, Fusion's chamber automatically adjusts and often uses lower pressure to keep the chamber and blade on its roller, and so extends blade life and reduces downtime.

Finally, because Fusion's FleXtreme and PCMC's eXtreme compressed-air dryers both use electricity, they can make better use of renewable energy sources than forced-air drying that relies mostly on natural gas, Pennings says. "However, to come up with improvements like this, you have to take some time to sit and think about them," he adds. "You have to look at every part, and see if it's necessary or not. Everyone can think of ways to make their machines and applications more energy-efficient and sustainable, but it won't happen overnight."

Consequently, while there are many ways to go green — from increasing machine efficiency to designing new equipment and products — all can produce positive results and revenue if they're given time to grow and thrive. The only way to lose is to not play.

About the Author

Jim Montague | Executive Editor, Control

Jim Montague is executive editor of Control. He can be contacted at [email protected].