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?
Signs of Old Age
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, 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.
"Other reasons why we periodically upgrade our automation systems include improving HMIs and help screens, the need to control robots from a common machine control platform, improvements to servo performance and control, better data collection and tracking, automated data transfer to devices such as printers, and the need for vision systems and vision inspection," Bahr concludes.
Bill Stewart, president of Stewart Engineering, 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 of Muskego, Wisconsin: "Does the machine work well now, and will it stay working?"
Darren Elliott, global technical resource manager at Rockwell Automation, 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, 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."