It’s been called the new world of motion control—namely, the integration of motion control with discrete control and perhaps even safety in a single controller and a single control program. Consumers, whether of phones or factory automation, are rightly wary of the claims of those with something to sell, who sometimes seem to find a new world around every corner. Still, there’s a compelling case to be made, one which seems to align with the general thrust of automation technology.

“We believe this is part of the natural evolution of plant floor technology,” says Brian Deal, packaging manager for controls supplier Schneider Electric, Palatine, Ill. He cites, as one of the prime movers in this evolution: the ongoing growth in computing power.

 “Today, we are able to provide the controller with a great deal of information from the drive, and from the motor itself. For instance, we load an electronic nameplate into the encoder so that whenever you wire up and power up a system, you get information about that motor, its model number and serial number and so forth, back at the controller level.”

The potential advantages of this integrated, information-rich motion environment are many. Mike Burrows, director, market development for Rockwell Automation Inc., the Milwaukee-based automation vendor, supplies another one. “Once you are able to perform the functions of time synchronization and high-speed motion control in the same box and the same program with your discrete control and your safety control, you get much better interaction between the pieces of your overall system.”

He stresses that integration simplifies. This is not only in terms of programming and engineering time, but physically as well. “You reduce the number of components, wiring, and communication interfaces and gain a smaller control cabinet.” It can also aid in machine and packaging-line optimization. Consider motor selection. This can be automated, and made more precise, through evaluation routines resident on the controller. Users can quickly pinpoint the right combination of performance and energy efficiency for their range of applications, while assuring that they are not buying larger and more expensive motors than they really need.

Electronic line shafting

All of this translates into cost savings. Perhaps even more importantly, it promotes flexibility.

Computer-aided advances in motion control technology have been aiding the packaging industry’s market-driven quest for greater flexibility for some time. The move away from mechanical line shafting to electronic line shafting is a case in point.

“Electronic line shafting is becoming much more common,” notes Rob Rawlyk, applications manager for Beckhoff Automation LLC, a Burnsville, Minn., automation supplier. “The big reason, of course, is flexibility.” By replacing cam plates and other mechanical line-shafting components with controller-driven electronic functionality, changeover times can often be reduced from hours to minutes. “Our customers are saying the batch sizes of the products they make are becoming smaller and smaller, so this sort of flexibility is becoming increasingly desirable.”

David Kirklen, packaging industry business developer for vendor Siemens Industry Inc., Alpharetta, Ga., concurs. “We’ve been seeing a lot of interest by packaging companies whose machines demand greater flexibility, and electronic line shafting is a part of that. Companies don’t want to have to go through a huge mechanical reengineering effort to be able to produce a new product.” He notes that electronic line shafting has other benefits as well. “By reducing the number of mechanical couplings and linkages in a packaging machine, you are reducing your maintenance requirements as well. In addition, it allows you to reduce the machine’s size.”

Good…but not good enough, maintains Schneider’s Deal, whose company is pushing its own take on the electronic line-shafting concept. The company calls it Intelligent Line Shafting (ILS). “ELS (electronic line shafting) has been enhancing packaging machine performance by replacing mechanical line shafts. However, because most machines run off the virtual master axis, the speed of the machine is fixed. This can limit the performance of a machine.”

He observes that by increasing the virtual master’s velocity, all cycle times are reduced—motor speeds, accelerations and decelerations—for all axes equally. This limits the performance of the system to the “weakest link,” even if the remaining axes are capable of higher performance. “To put this in real-life terms, it’s like telling a NASCAR driver that he has to drive the track at the same speed all the way around. The driver would be limited by the maximum speed of the toughest corner on the track.”

One additional drawback of ELS, Deal continues, is that if critical motion profiles during a machine ...