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By Dan Hebert, PE, Senior Technical Editor
If you're a machine or robot builder OEM, a debugged, reliable and functional control system is a joy. You've had the system for a while now and sold enough machines to repay the initial investment you made in marketing, research and development, and implementation. The control system has been incrementally improved for years, the hardware is reliable, and you know how to fix it when it fails in the field. In short, it does its job.
But every control system has a lifespan, and sooner or later you'll have to update or replace it. Has your time arrived? How do you tell?
Lots of factors influence upgrade decisions, many of them performance-related. "An automation system upgrade should increase OEE, often an important benefit for our customers," says Mel Bahr, executive vice president at MGS Machine (www.mgsmachine.com), a builder of horizontal and top-load cartoning machines, and product feeding equipment (Figure 1) in Maple Grove, Minnesota. He says automation upgrades often make it easier to change products, crucial for MGS's contract packaging clients, and increases in speed often are realized.
Bill Stewart, president of Stewart Engineering (www.stewartengineeringinc.com), a system integrator in Boerne, Texas, says, "Factors that determine if a machine should be upgraded include the use of old relay logic, no documentation or discontinued hardware."
We've heard the lament before about parts being hard to find, but in this article we want to look beyond the obvious "replace it because you can't get parts" answer. Nowadays, suppliers that specialize in stocking old parts, eBay, and more vendor support of legacy equipment make it possible to find almost anything you need.
Obsolete parts and discontinued software support just aren't the leading reasons to update control systems. Instead, two key questions need to be answered, says Dan Jensen, senior automation engineer with Nelson Sales (www.nelsonsales.com) of Muskego, Wisconsin: "Does the machine work well now, and will it stay working?"
Darren Elliott, global technical resource manager at Rockwell Automation (www.rockwellautomation.com), says customers will tell you when it's time to upgrade. "When an OEM's customers start to ask for the latest and greatest control system features, it could be time to upgrade, since those end-user pain points often dictate the need for machine upgrades," he says. "For example, end users might need to lower maintenance costs, or they could be experiencing frequent nuisance trips and need a more reliable machine."
Jensen sees another sign: "Does the computer software work on newer laptops, or do you keep an old one with special software on the shelf just in case?" Some machine builders keep a PC/XT laptop with floppy drives around for this reason.
Maintaining legacy systems can get expensive as older components can have high failure rates. "Failure of obsolete components are generally unpredictable and almost always occur at the least convenient time," says Phil Gilkes, director of product support at Intelligrated (www.intelligrated.com), a builder of material handling equipment in St. Louis. "The downtime can result in significant costs to the end user."
Finally, it could be getting harder to sell the kind of controller you've been using. "Traditionally, robot manufacturers used their own proprietary controller, which was complicated to program and had to be interfaced with other system components," Gilkes says. "Now, complete robotic systems can be controlled by a single, powerful PLC. Customers are far more comfortable with PLC controls and tend to prefer systems and vendors that use them."
The same is often true for machine controls based on old relay logic, ancient programming software and proprietary systems. The control system might work, but customers won't buy it.
Sometimes a legacy control system can have none of the problems noted above, but it just can't handle all the new tasks that have come up in recent years. Michael Senske, president/CEO of Pearson Packaging Systems (www.pearsonpkg.com) in Spokane, Washington, sees two major reasons to upgrade—a need to communicate with other machines, and the need for a modern HMI. "Many of our customers want to integrate machines to operate as a unified system, and they want to pull performance data from each machine for their ERP system," he explains. "A modern HMI lets customers more easily accomplish changeovers, perform routine maintenance, and monitor machine or system performance." Pearson makes top-loading case packing equipment, and offers secondary packaging solutions using robotics, case packers, case erectors, bag inserters, uncuffers, and case sealers (Figure 2)."More manufacturing plants are integrating the machine control with MES and ERP systems," adds Rick Roszkowski, senior director of marketing at Cognex (www.cognex.com). "If your current automation system cannot provide the data needed by these systems, it might be time to upgrade."