Motion Control Resources
Pharmaceutical Packaging Get Flexible with Motion Control
by Kristin Lewotsky, Contributing Editor
Motion Control & Motor Association Posted 08/01/2007
Offering precise, repeatable motion and changes on the fly, motion control helps make pharmaceutical packaging more economical.
In one way or another, the products manufactured by the pharmaceutical industry touch us all. It is somehow appropriate, then, that in one way or another, motion control touches the operations of just about every single manufacturer in the pharmaceutical industry.
Indeed, motion control is helping pharmaceutical manufacturers remain competitive while dealing with a tough marketplace, a challenging regulatory environment and the ongoing threat of piracy. Not only does motion control offer inherent flexibility plus compatibility with traceability requirements, machines can also be equipped to work with the radio frequency identification (RFID) tags that are the first line of defense against counterfeiting.
“We’re seeing the global market requiring RFID for counterfeiting prevention, and process control based upon that,” says systems integrator John Odenthal of Motion by Odenthal (Geneva, Illinois). “That means that you need flexibility with your production facility and that’s where motion control becomes a major player.” Indeed, he sees flexibility and efficiency over the lifetime of the machine as being the overall trend in packaging as an industry.
Back in the day, companies designed dedicated lines for their products. Switching over mechanical camming could take hours, which meant production time -- and revenue --lost. Ultimately, commissioning a line and leaving it that way, even if it was only used 15 to 20% of the time, was considered most practical.
No more. In today’s competitive business environment, manufacturers have to maximize return on investment. “Multi-product production and flexible packaging lines are becoming more prevalent,” says Greg Killien, pharmaceutical program manager at Siemens Energy & Automation Inc. (Norcross, Georgia - www.siemens.com). “It’s [about] reducing the switchover time, and in pharma in particular, there’s a requirement to reduce human error associated with those switchovers and with different recipes.”
That’s where recent developments in motion control really come into play. Previously, pharmaceutical packaging systems used small pneumatic cylinders, but these lacked force feedback, positioning feedback, and, thus, repeatability. In what has become a broad trend across all manufacturing, the pneumatic cylinders have been replaced by servo motors. “Servos that have the form factor of small pneumatic cylinders are changing and have changed the labeling and filling business,” Odenthal says.
And as they’re changing those businesses, the servos themselves are changing. “Instead of doing things in the 1 KW to 2 KW range, we’re moving to the 5 KW range -- down into the stepper range -- but you’re still doing it with servos,” he notes. “[We’re seeing] 5-mm-diameter actuators in which the actual rod is perhaps a millimeter or several millimeters in diameter. The whole assembly is smart and is no bigger than 20 to 30 mm, centerline to centerline.”
These dimensions allow systems to perform tasks sequentially and in parallel. Consider filling. Traditionally, machines filled syringes or ampoules in arrays, putting the same amount of the same drug into each container simultaneously. “That is not the way things will be done,” Odenthal says. “Rather than having a single pump station being driven by a single actuator, you’ll have individual ampoules being filled by individual actuators.”
Machines today are filling on the fly. Traditionally, the container stopped under the filler, where the dispensing element was introduced. When the container was filled it would move on. All of that took precious time. “Today, the dispenser head is synchronized to the container, so as it’s filling, you’re retracting the filler head from the container,” Odenthal says. This has greater benefits than just time savings. “[By retracting the filler head,] you’re not foaming the product and yet you’re maximizing throughput.”
Of course, these new systems do present challenges. It’s no longer feasible to use centralized architectures, for example. Gone are the days when a PC or PLC with a motion card would control a cell of four to eight axes. Now, the number of axes in a cell can be many times that, and the cells themselves are linked to a distributed control system through a communications bus such as Ethernet or CANOpen. The reason is purely pragmatic. “There is a difference between the ability to be flexible and [achieving] cost-effective processing,” Odenthal observes. “If I’ve got to program my whole central computer to deal with a small change on a particular axis, there is a cost involved in doing that, whereas if I could just change the axis or change the parameter file to the axis through a distributed control, the cost is now significantly lower. We’re now much more likely to implement the changes.”
Distributed control and modularity are the two faces of today’s motion control designs. Several decades ago, machines had line shafts and mechanical cams. Today, the mechanical cams have been replaced by the electronic cams of servo motors. At the same time, the machines tend to be constructed of multiple modules, often from different manufacturers.
While modularity offers benefits, it presents challenges of its own. Quite aside from the issue of cross-vendor interoperability, getting the modules themselves to run together in a distributed architecture is nontrivial. Consider a machine consisting of three modules, each of which is run by a different controller. “All three controllers have to be synchronized with each other and we have to be sure the electronic line shaft goes from one controller to the other controller,” says Holger Grzonka, Industry Consultant, Packaging of Siemens. “You need to have very fast communication and synchronization.”
Today, with an approach like Siemens’ distributed synchronization, instead of changing out mechanical cams, you simply adjust your software. This can be performed rapidly, even from one product cycle to another without stopping the machine. “Say you have a bag-making machine and the second bag must be shorter than the first bag,” Grzonka says. “You recalculate your cam profile during the time the first bag is being manufactured. When the next product cycle starts, you say ‘change the cam profile’ and the pre-calculated cam profile becomes active.”
FDA Regulations and Anticounterfeiting
Pharmaceutical manufacturers work in one of the most rigorous regulatory environments around. Complying with traceability requirements such as 21 CFR Part 11, pertaining to digital signatures, presents significant challenges. “We’re seeing requirements coming out from the government that have changed the production requirements of whole lines,” Odenthal says, citing a pharmaceutical company that retrofitted an entire production line based on a single government regulation. Interestingly, he sees the process going both ways -- process changes implemented by companies may actually force the FDA to modify present standards. “What I’m talking about is individual lots getting smaller and smaller and the requirement for traceability of the manufacturing process becoming more and more rigorous.”
Traceability also helps combat counterfeiting -- which brings us full circle to RFID. “Counterfeiting is a major issue to the people I speak to in pharmaceutical processing,” says Odenthal. “They would like to have as much non-simplistically replicable information on their container as possible so that it’s more difficult to duplicate.”
Of course RFID tags represent data that has to be read and processed. “It will change the requirements for bus networks at the cell,” he predicts. “If I have to transmit data over 100 axes and that data includes all the information on an RFID tag, the motion control overhead is going to be relatively small. You tend to have a single bus and a single architecture rather than have multiple protocols.”
Grzonka, for one, sees a big need to integrate the RFID systems into the overall packaging machine. “Most of the systems are standalone; they don’t interact with the motion control of the machine. I think manufacturers and [machine builders] should think about the benefit of integrating RFID and also the labeling and the vision reading into the machine control.”
In the end, it all comes down to flexibility. Odenthal predicts that form factor will be of increasing performance in the future. Performing multiple tasks at a higher rate means doing them in parallel with multiple units. Such an approach offers the most freedom. “When you’re in a transitional position as we are today with things like RFID, you don’t have a choice -- you have to build a machine that has the capability of morphing into a machine that will be useful two to three years down the road.”