Used Robots: Do They Make Sense for Your Company?

A look at the pros and cons of used robots

Although prices of new robots have dropped in recent years, a used unit still represents a significant cost savings, in some cases, more than 50 percent.

Used robots are 'attractive especially for smaller companies, which don't want a large capital outlay,' explains Steve Holland, Director of Controls, Robotics and Welding at GM's Tech Center in Warren, MI.

Buying a used robot also enables facilities to stay standardized on a certain model and controller. 'With controller technology changing every couple years, it's important to customers to stay standardized on one control,' says Phil Marshall, vice president of Servo-Systems, a used robot dealer in Montville, NJ.

A 50 percent cost savings and standardization were the two main reasons behind the purchase of a rebuilt robot from Motoman, West Carrollton, OH, by Collins & Aikman Production Co., Automotive Fabric Division, Old Fort, NC. 'We already have a bank of spares so we don't need to stock another $15,000 or $20,000 worth of parts to support it,' explains Jack Davis, plant engineer.

Since operators and maintenance personnel are already familiar with the model, which is used for hot-melt adhesive application, no additional training was necessary when the unit was installed.

Other advantages of used robots include the likelihood of quicker delivery and the confidence about the reliability of a field-tested unit.

Despite the benefits of buying used robots, there are still many reasons to buy new robots. 'If you are buying a large number of robots to do an automated line, you may want to take advantage of the fastest, newest robots available to minimize the total number needed to perform a particular application,' says GM's Holland, who is more likely to sell a used robot than buy one, unless he's trying to match a certain existing model on the shop floor.

Another reason to choose new is if a particular feature is needed. Premix, North Kingsville, OH, a custom molder of composite moldings for automotive, electrical and other applications, has exclusively purchased used robots, but is considering a new unit for an upcoming project because it requires a 180-degree shoulder bend to minimize floor space requirements. 'We constantly evaluate which direction we want to go, new or used, for each application,' says Bill Lewis, automation specialist at Premix.

New robots may offer more powerful software and enhanced safety features, which automatically slow or stop robot movement if an operator encroaches on the work cell. New robots also may be simpler to set-up and operate since OEMs have made ease of use a priority in recent years.

Although life span is dependent on operation, maintenance and to what degree a used unit has been overhauled or rebuilt, new equipment may provide a longer service life and warranty.

'One factor to consider is the original design life of the mechanism,' notes Joe Campbell, Vice President of  Marketing at Adept Technology.  'Extending the life of a robot with a 30,000 hour design life for its core drive train and bearing structure is not good economics.'

Finally, integrator preference may play a role in the decision of new versus used.

Selection considerations
When it comes to selecting a used robot, numerous factors should be considered to ensure a successful project.

For a first-time robot installation, pick an easier task like machine loading or parts handling rather than something more complex like trimming or polishing, advises Steve Antenen, president of Antenen Research, a Cincinnati, OH-based dealer, which generally has 200 to 300 used robots available for sale at any given moment.

Understand what you want the robot to do, how it needs to move, required cycle time and work envelope constraints.

With the U.S. robot population now estimated at 100,000, used units are plentiful. However, unlike 10 years ago when many used robots had barely been turned on because inexperienced buyers bought the equipment and it didn't work out as expected, today's used units are likely to have seen more service. 'The market has matured,' notes Marshall.

How old the robot is doesn't seem to matter much. Over the years, Premix has purchased seven used Fanuc robots (five in use and two spares), mostly from Antenen. Ages range from 7 to 20+ years. 'For pick-and-place and machine tending, you don't need to be on the leading edge of technology,' Lewis points out.

'[Judging] age depends on what it was doing,' says Marshall. It also depends on how the unit records time. While a unit with 20,000 hours on its clock generally is viewed as halfway through its life span, this can be misleading, particularly with older units, which tend to be equipped with an hour meter, which records when the controller is on. Since a unit may be powered up during long periods of inactivity, actual working time may be significantly less than clock time. To provide a more accurate picture of usage, many newer models register servo time, as well.

Make sure you understand what has been done to the robot in the way of overhauling or rebuilding. An overhaul typically replaces the most obvious bad parts and applies a coat of paint to freshen the unit's appearance. Rebuilding or refurbishing will reconstruct the robot from the ground up. The latter should provide a life span equivalent, or nearly so, to that of a new unit, assuming proper maintenance practices are followed.

Prior to sale, Servo-Systems technicians go through the robot mechanically and do whatever is needed to support a warranty of 180 days for newer units, 90 days for older ones. The technician removes anything added to the controller and restores it to the state it was in when the unit was shipped from the factory. Manuals are assembled, and repeatability tests are run.

At Antenen, technicians typically install the latest generation of software available. The company also supplies a complete set of manuals and retains a set in-house to aid in responding to future technical support requests.

'Know your vendor, if not by experience, then by reputation,' advises Antenen. Go watch the robot run. Bring parts to test and check repeatability.

Look at the availability of tech support. If you need it 24/7, is it available 24/7? 'If the seller can't tell you how to hook up the input/output or wire in the tooling or explain how to write a rudimentary program, you're buying from the wrong people,' warns Marshall.

Is a warranty offered? If so, review what it covers and for how long, as warranty conditions vary widely with terms ranging from about 90 days to one year.   'Be sure to define your complete support expectations,' says Adept's Campbell.  'Do you expect factory trained field service and full warranty coverage?  Training classes?  Same day parts shipments from stock?  Dedicated phone support?  Not all used equipment vendors can provide complete services.'

Finally, 'Don't make the decision solely on price,' warns Marshall. 'When you buy on price in the used market, invariably you give something up, usually tech support,' he explains.

Purchasing methods
Prospective buyers of used robots have long relied on dealers, direct sales from owners, OEMs and traditional auctions. Today, purchases also can be made via on-line auctions.

Experimenting with this format, the GM Tech Center plans to dispose of about 100 robots this month through the GM TradeExchange.  It's an automotive trading exchange run jointly by GM and Commerce One Inc. Lots slated for presentation include units from Fanuc Robotics North America, Inc., Rochester Hills, MI, and ABB Flexible Automation, Inc., New Berlin, WI, for spot welding, material handling and sealant application. Potential bidders are invited to participate and alerted via e-mail regarding equipment specs and auction timing.

'It's a way to pick up some good condition robots at very attractive prices,' says Holland.