Running robots mean flowing profits

That means selecting a repair shop is an important decision.

By Scott Phillips

You find them in most automated manufacturing environments, happily going about the tasks set out for them. They're steady workers, known more for their output than their personality. Some are large, heavy brutes whose sole job is to yank transmission bodies from an overhead conveyor. Some are small, nimble, quiet drones that place component A into slot B six-thousand times a day without ever uttering so much as a sigh of complaint.

A new, genetically engineered breed of superworkers? Nope. They're robots. And they're quietly attaining the prominence predicted for them during the early 1980s. After an initial craze that had engineers scurrying around, overusing, and misusing the technology--in one automotive plant in Detroit they're still laughing about the time a couple of paint robots began painting each other--robots settled into their place as practitioners of the repetitive, the humdrum, and the dangerous.

As much as they add to the productive manufacturing capacity, robots are not the perfect, trouble-free automatons we'd like them to be. Even though they perform spectacular feats of fluid, graceful output, they are still only machines--conglomerations of metal, plastic, and circuitry that can--and often do--break down.

If you're using robots in your plant, you've experienced the occasional, irritating breakdown.

Maybe it was a circuit board from the control, or a bad wrist assembly, or a drive. In any case, a high-tech piece of gear needs to be fixed and you had to decide where to send the component for repair. Many companies use the original equipment manufacturer for repairing their robot components. Increasingly though, robotic users are turning to independent repair companies for the maintenance of their systems. It's not that the OEMs do a poor job of repairing components, but that the increased dependence on robotic systems created a need for faster service.

In the United States, there are only a handful of independent repair companies qualified to repair robotic components. Because they specialize in repair, they usually turn your components around faster than the OEM. Some independents repair just the mechanical components, while only a few repair the electronics. Fewer still repair the entire robot and controls.

Finding the best

These technologically elite repair companies repair the entire robotic arm and the control system and then test them as a complete system. When it comes to component repairs, each component is tested in its own host system. This use of system testing is just one of the many things you should look for when deciding on a repair source. There are some important elements you should consider when deciding on a repair source for your components.

First, does the repair company have the capability to test your repaired components in-system? In other words, does the repair company own the same systems you have in your plant? If you need a repair for a Kuka, Asea, or GMF component, you should expect that, before it is returned, it will be tested in a Kuka, Asea, or GMF system. This is probably the most critical factor in choosing a repair source because it is the only way to guarantee repair integrity. The better repair shops maintain all of the above systems and use them exclusively for testing purposes.

Secondly, can the repair company repair all the components in your system? Some repair sources are capable of individual component repair, but when the entire system is in question, you need to know that the repair source handles all of the components. Let's say you have a problem with the drive unit and the wrist assembly is looking a little shaky, too.

A qualified repair source can fix both, instead of farming out, or worse yet, returning your other components unrepaired. The better repair shops handle repairs for any and all components in a robotic system.

Third, does the repair company have an adequate stock of replacement parts? When your robot is down, the last excuse you want to hear is that the repair company is waiting on backordered parts. Make sure when you choose a repair source that they made the proper investment in replacement stock. Some independents carry sufficient stock for a particular line of robots. To ensure that your robots are serviced properly, make sure that the repair source carries a full line of parts, from a variety of manufacturers.

Fourth, what is the warranty on your repaired robot component? Most OEMs and some independents offer a limited, static warranty--something like 90 days from <I>shipment<I>. What you really need is a longer, "in-service" warranty. Under an in-service warranty, the warranty on your repaired component begins when the component is <I>placed back into service<I>. This means that you can shelve the component as a spare without sacrificing the guarantee. The better repair shops offer a 6-month in-service warranty on repaired electronic and hydraulic components and a 1-year in-service warranty on mechanical items like ballscrews and bearings.

Self defense

Hopefully, your robotic systems run smoothly and your need for repair from any source is minimal. Following is a checklist of measures you can take to minimize the need for repairs.

First, keep ballscrews and bearings properly lubricated. This includes the often neglected base bearing. You can improve the life of these mechanical items by using a high quality, synthetic lubricant. Take special care to ensure that the synthetic lubricant is not contaminated by other residual or incompatible lubricants. If this happens, the lubricant breaks down and leads to mechanical failure.

Second, regularly check the wrist assemblies. These mechanical assemblies are usually the first to show signs of wear and early detection of problems increases their life.

Third, as much as possible, keep airborne contaminants to an absolute minimum. Mechanical and electronic robot components are highly susceptible to excess paint vapors, airborne grease and, worse yet, metal dust.

Fourth, make sure your control enclosures are buttoned-down as tight as possible. Providing a safe control enclosure, free from contamination, prevents unnecessary breakdowns. Remove and clean the air filters regularly. Check indicator lights and inspect wiring for insulation breaks and deterioration.

Fifth, check and clean motor brushes regularly. This is one of the easiest and quickest ways to prevent costly breakdowns.

Sixth, maintain a cool environment for your controls because a robot is only as good as its program. If the robot receives faulty signals from its control because of heat damage, well, you get the picture.

These are a few of the many preventive maintenance measures you should take to ensure maximum robot life. For a more comprehensive list, contact the robot manufacturer or your repair shop. For further information on how PSI can help you with your robot maintenance, call.

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