Servos Find a Packaging Niche

Flexibility is driving more manufacturers to servo-driven packaging lines, but concerns remain about validation and the “blue screen of death” with PC-based controls.

By Alan S. Brown, Contributing Editor

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Although most pharmaceutical manufacturers keep quiet about their new equipment, servo-powered packaging systems are finally claiming their space on the factory floor. While these flexible machines have become a mainstay among consumer products companies, regulatory requirements have presented formidable barriers to their use in pharmaceuticals.

"The pharmaceutical industry is just getting into seeing the benefits of the servo world — the easy changeovers that make it economical to do short runs and small lots," says David Blauw, electrical engineering supervisor at Bosch Packaging Technology (Minneapolis), which has built several servo-controlled machines for drug makers. "Instead of taking four to six hours to clean, autoclave, and change cams and parts, you can simply reprogram the machine, load up a different type or size of vial and be up and running in minutes." Servo systems are also simpler, cleaner, less prone to breakdown, and easier to clean, Blauw notes.

The problem is that servo systems typically rely on PC-based control systems. They present far more validation issues than the PLC controls and mechanical linkages of conventional shaft-driven packaging systems.

Yet many pharmaceutical firms are willing to go the extra mile to put servo machines on the floor, especially as they commercialize more specialty drugs requiring varied packing options, Blauw explains. "With cost pressures from competitors, insurers, and large buyers, pharma companies are looking for machines that give them more flexibility," he says.

An electronic system does that far better than a mechanical system, Blauw adds. “Pharmaceutical companies may be hesitant to change from the mechanical realm where they're dealing with a known entity, but their production needs are forcing them to do it," he concludes.

An Allen-Bradley MP-Series servo. Courtesy of Rockwell Automation.

Servo advantages

Business pressures aside, servo-based equipment offers advantages over shaft-driven equipment, says Mike Wagner, business development manager at Rockwell Automation (Milwaukee). "Before servos, packaging machines had one large AC motor running at a fixed speed," he says. "Mechanical linkages off the main shaft would control each packaging process, translating shaft motion from one speed to another or from rotational to linear motion.

"For each revolution of the main shaft, you had one product coming out the other end,” Wagner continues. “Every time you wanted to go from vials to bottles or change the size or shape of the package, you had to reconstruct the machine."

Servos change the game. Instead of mechanical linkages to a main shaft, each servo (which includes motor, gear head, and software) operates independently.

"Everything can be modified — pressure, velocity, position," says Wagner. "Before, it would take seven hours to make those changes, so you didn't want to do it unless you had a large enough lot to run effectively. Now you can make the changeover in three to five minutes. It's like loading a recipe."

Freeing servos from the drive shaft enables them to adjust independently to each event during the packaging process. "Imagine a simple low- to moderate-speed bottling line," posits Bob Hartwig, vice president of Pester USA, a subsidiary of the German packaging equipment firm. "It's made up of a host of simple machines, all of them interdependent and working in concert. As the system collects data, the servos on the line can adjust independently to any production problem as it occurs."

Servos also offer an entirely new level of speed and precision, adds John Kowal, global marketing manager for Germany's ELAU, Inc., Europe's leading manufacturer of servos for packaging. Kowal estimates that 70 to 80% of the stretch banders, overwrappers, case packers and palletizers now sold to pharmceutical companies use servos.

"One of the great things about servos is their closed-loop feedback,” he says. “Our servo-based capper controls torque to +/- 0.02% versus 20% for a standard clutch-drive capper. We know exactly what values are. We can actually store the torque value for each cap, so if there's a recall, we may only have to recall 1,000 bottles instead of one million bottles." The same data can also be analyzed for trends that indicate wear or a need for maintenance.

Since servos use much smaller motors, maintenance is rare. "Servos have a mean time between failure (MTBF) of 200,000 hours," Wagner says.

21st century manufacturing

Finally, servos are far more affordable than in the past. "Five years ago, servos cost about $10,000 a pop," says Hartwig. "Nowadays, they cost about $5,000 each and prices are still falling." On an inexpensive machine that costs $100,000, adding 10 servos would increase the price by 50%.

Add those same 10 servos to a larger unit costing $500,000 to $1 million and the cost is hardly noticeable. The payoff, however, is huge: a large, fast line that is flexible enough to package solids and liquids in a variety of containers in short and long production runs.

"They're faster, more accurate, easier to control, easier to maintain, easier to implement, and longer lasting," says a project manager at a leading pharmaceutical manufacturer who did not want to be identified. He says his company is installing all-servo packaging lines when old systems wear out and when it builds new plants. "We're in the 21st century, and this is a new way to run plant. Servos help us predict problems before they occur. They tell us where to troubleshoot. Everything about them is easier. They are a step above driveshaft machines," he says.

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