Dual Motoman ES165 Expert Spot robots spot weld automotive seat frames and related components.

The XRC pendant and NX100 programming pendant sport user-friendly touchscreens.

Motoman's NX100 control allows for easy programming of a simple weld procedure.

A new arc-welding robot has a hollow-arm design that protects its torch cable.

As welding robots have become more economical, productive and reliable, their use has expanded from automobile assembly plants into job shops. However, sometimes it takes an outsider to manufacturing to show how far robotic-welding technology has come in recent years.

For example, two Motoman UP-series robots looked at home in the 2003 action film "Paycheck" with Ben Affleck and Uma Thurman. Originally, the Motoman robots were slated to be in the background of the $5-million high-tech biosphere laboratory set, but after the film's director, John Woo, saw their speed and capabilities, the robots were given action roles, even interacting with Ben Affleck and other actors in several key scenes.

To the movie's director, the robots' speed and motion translated to visual excitement. To manufacturers, this speed translates into more parts per hour and higher profits.

The movie's crew was surprised how quickly and easily they could create and edit the robot programs. They were familiar with programmable-motion carriages used for panning movie cameras, but these require hours to implement even simple changes. On the movie set, the Motoman technician developed several program choices in a matter of minutes, allowing the director to pick the version he liked. The technician made minor program changes in a few seconds right before the movie crew's eyes.

The crew also found the robots economical. While cars, houses and even welding power sources have increased in price, prices for robots have dropped. Today, shops can purchase a welding cell — a robot, positioner and safeguarding — for about the same price as a bare robot in the early to mid-1980s.

Beyond the movie set, the Hollywood crowd was impressed, but what about manufacturers exploring robotic automation? They want easy-toprogram systems that offer performance necessary to boost productivity and to benefit their bottom lines.

The Motoman robots used in "Paycheck" were six-axis UP-50 and UP-20 models, both with a lightweight XRC controller. The screen on the programming pendant is a backlit monochrome display that uses icons and text to relay information to the user. Today, Motoman offers a moreadvanced control, the NX100, which it introduced at the 2004 AWS show, along with the EA1400N robot manipulator.

The NX100 robot controller keeps the lightweight and ergonomicfriendly pendant used on the XRC, but adds a larger, color touchscreen display. Programmers simply touch a menu button to display more information, or they use cursor keys on the pendant.

The unit displays programs in Motoman's Inform language, which has been part of the last three generations of controllers (XRC, MRC and ERC). This makes it easy for plant personnel to learn the NX100 controller and the new features Inform III offers. Users can save all the Inform programs from the controller and display/edit them from a computer with any text-editing program.

The XRC pendant and new NX100 programming pendant sport userfriendly color touchscreens.

Learning to program the unit is relatively easy — almost anyone can learn the basics. Half of the keys on the pendant are motion-related, letting programmers move robots to desired positions with particular orientations. However, Motoman recommends companies send welders to a one-week training class to learn how to program the robots.

The robots also make use of the skills of experienced welders, who know what torch angles to use and how other parameters affect welds. Hence, the robot software can interpolate motion between points to move in a straight line (linear motion) or in an arc (circular motion). The programmer can then enter an exact speed for the tool center point (TCP), which normally is defined as the end of the weld wire.

Using interpolated motion, a programmer records points where a weld starts and ends, and the robot calculates the weld path. Programmers insert points between welds to ensure the robot moves around parts and tooling.

Keys on the pendant let programmers step forward and backward through programs to see if robot paths are correct and will not crash into anything. If there are problems, they can add instructions to the program, such as starting or ending an arc, turning on an output, waiting for input from a device or calling another program. Such instructions include provisions to enter desired amperages and voltages for particular welds.

The NX100 expands the XRC's capability to control as many as four robots. All four programs can run at the same time with each robot operating independently. Anti-collision software ensures the robots will not run into each other.

A Tier-1 automotive supplier in Canada uses a large Motoman robot to handle a part while two process robots arc weld it. With only four cells using robots as flexible part positioners, the manufacturer matches the throughput of six traditional robot cells with positioners. This approach reduces capital costs and provides tremendous flexibility for future part changes that only require the robot grippers to be changed.

The XRC's built-in programmable logic control (PLC) functions let it control more than just robot motion. For instance, it has up to a 10,000-line program capability and allows drag-and-drop ladder programming. In monitoring mode, the pendant highlights true logic in red to simplify troubleshooting. Eliminating the need for a PLC to control tooling and conveyors also reduces system cost and complexity.

The NX100 has built-in Ethernet communication and uses Windows CE to display information such as documents, manuals and web pages from other devices on the network. The robot can share information with networked computers. For instance, the robot can send e-mails that notify plant personnel as to what time of day a wire drum needs to be changed. The touch screen also can be programmed to operate as an HMI with buttons and status indicators for the operator.

Finally, just as the general-purpose UP50 and UP20 robots wowed movie personnel, plant personnel have been impressed with the applicationspecific EA-series Expert Arc welding robots. These robots have hollow upper arms and wrists that protect the torch cable and minimize cable fatigue. This design extends the torch-cable life versus systems that mount the torch on an arm offset from the wrist. It also reduces downtime, saving thousands of dollars over the life of the robot.