Upgrade of legacy control system can improve productivity

In today’s no-spend environment, it might be tempting to continue repairing your aging or even outmoded process controls, rather than upgrading to a microprocessor-based system. Budget constraints and maintenance contracts might preempt any discussion about upgrading controls until you reach the point where you simply can’t fix them anymore.

In reality, if you’re trying to save money by prolonging the life of an outdated process control system, you’re not only investing in false economies, but you’re missing out on technological advances that can pay a sizable ROI derived from savings on downtime, improved system efficiencies, remote system capabilities, energy savings, increased safety or a combination of those benefits.

Eventually, outmoded equipment upkeep becomes more expensive than purchasing new. By that time, a staff engineer will have to consider retrofitting it or upgrading it. Ironically, after an upgrade, they begin to realize benefits they could have already enjoyed for perhaps years.

Graham Packaging worked with automation and controls specialists to maintain our edge in customized packaging. In recent years, Connell Industries helped us identify needs and opportunities that could be addressed through system upgrades and replacements.

We operate a tabletop conveyor depalletizer system and another aseptic, water-wash line, in an enclosed Class 100 clean room. We struggled with nuisances and jams. The operators had a hard time understanding that the problem was based on the information the machine gave them. They’d have to try several different solutions.

By upgrading, we saved four hours to six hours of downtime each month in nuisance problems. A typical stop in the past could take up to seven minutes to get the machine running again. This piece of equipment has five access doors, and the machine didn’t identify which door was open, so we’d have to operate each door to see which one was open. This machine also has pumps and valves. If there was a valve problem, it didn’t give specifics on what to look for or which valve was the problem. We’re moving 24,000 bottles/hour, and the equipment isn’t exactly perfect all the time. We didn’t have a lot of catastrophic failures, but if you’re getting that much downtime each month, you’ve got an problem.

We brought Connell in to look at revamping and upgrading the controls and interface for operators. We run an aseptic process — a spray booth that washes the packages. The line design was flawed, so we tried to minimize people walking under the conveyor. The control panel was on one side of the machine, and the access panel was on the other side.

Microprocessor-based control hardware, customized software and versatile communications devices give us unprecedented ability to monitor, regulate, protect and improve processes. This is especially true when upgrading from electromechanical and older electronic systems. The communications capabilities and improved abilities to monitor, analyze and more tightly control processes make upgrading to state-of-the-art digital control systems a powerful tool.
This is pretty much the best option we had. We didn’t want to use second-generation equipment. We wanted the most up-to-date industry-standard equipment, so we could get replacement parts. We didn’t want to rely on specialty equipment.

We upgraded with a new touchscreen HMI, Rockwell Automation’s Allen-Bradley on-machine PLC and two Allen-Bradley VFDs/encoders. We added remote monitoring so senior management could see the system to see process variables. We had an OPC-server-driven monitoring system accessible through the Web, and we have a VPN connection with cameras installed on the line, so we can get external support, which was there before the installation of the monitoring device.

This kind of system represents a whole new ballgame. The ROI transcend those that industries are accustomed to gaining when they retrofit or upgrade equipment. One of the primary benefits of upgrading process controls is system reliability. That translates into other key benefits, such as product quality, uptime and production capacity.

One key metric is how much labor we cut to get this package out the door. Also, did we decrease the time it takes to repair? Better diagnostic tools give us the ability to do those. We’re not down for each event as long. The data monitoring system allows us to react more quickly and keep ahead of problem areas.

The equipment tells more than it used to. Even when you’re not there watching it, you can see an increase in events. By having insight into the equipment as it’s running and being able to monitor key components in the line, we don’t rely on perception-based or importance-based decisions by individuals. We cut down on the human factor by having the equipment telling them. Instead of spending more time on reactive maintenance, we can watch trends. Everyone does PMs and SIPs and CIPs. We can line up our resources to be available. The more invisible we are, the better off everyone is.

The automated delivery of reliable information via advanced interfaces such as an HMI also enables more accurate and appropriate system support. With this capability you don’t have to rely on human interpretation of status. Important functions such as troubleshooting and failure analysis can suffer from an individual looking at a machine, as in the old days, and developing analyses and solutions. If you had five people looking at the same situation with the same equipment, you could easily get five interpretations and five proposed solutions.

Intelligent equipment, such as today’s process controls, can tell accurately identify the problem and possibly the sequence of events that led up to the problem. It also streamlines our ability to integrate, troubleshoot, identify and evaluate process efficiencies and opportunities. More advanced process controls provide critical information regarding when new process equipment is needed and the variables that help develop equipment specifications.

Being able to pull down the data for a specific time period shows when a trend occurs. When these trends require action, we can schedule the appropriate maintenance accordingly. And, we can trend how differently that product affects the same production equipment and quantify how some products cause more wear and tear than others. By knowing that trend, we can more accurately schedule maintenance and thereby improve system reliability and uptime.

Some of the feedback that empowers maintenance savings and uptime comes from advanced network communications, including supervisory control and data acquisition (SCADA) systems. “Higher system integration” is becoming more attainable through Internet-based automation and control systems using the existing Ethernet communication network already installed in most facilities, as well.

In some senses, improved system reliability is like an iceberg, with uptime and resulting productivity improvements representing the more visible, and to many companies, the most important cost benefits.

Savings on system maintenance and repair can be tied to appropriate automation control upgrading programs because of the ability to get system-wide feedback. This gives new opportunities to institute improved maintenance programs, whether preventive maintenance or corrective maintenance. This information also gives added flexibility in maintaining equipment.

Michael Deitz is project manager at Graham Packaging, which designs and manufactures blow-molded plastic containers. Contact him at [email protected].