Robots are on the move

Sept. 1, 1999
These flexible workers are making welds, moving parts, and cutting materials everywhere from large automakers to their smallest suppliers.

These flexible workers are making welds, moving parts, and cutting materials everywhere from large automakers to their smallest suppliers.

Fanuc Robotics' overhead rail-mounted, top-loading robots free up floorspace and perform a variety of tasks in a single cycle. They are designed for load/unload applications in the machine tool industry.

The Arc Mate 50iL from Fanuc Robotics has a double-jointed design, an advantage in overhead welding situations. Its multiple mounting positions and tabletop size also increase installation flexibility.

The ABB IRB 2400 robot plasma cuts the panel of an Antique Auto Sheet Metal Ford Roadster replica.

The Motoman SK16 is a six-axis load/unload robot. Its slim design improves part, machine part nest, and die accessibility.

Approximately 92,000 robots are now doing welding, material handling, machining, and a host of other jobs in American factories, and this number is only projected to grow. In the automotive industry, for instance, automakers and their suppliers are moving away from dedicated lines towards flexible systems that combine machining centers, robots, and other equipment. And small and medium-size suppliers are not left out: As robots get smaller and their prices drop, they will make their way into more jobshops.

The North American robotics industry sold more robots in the first quarter of 1999 than in any previous quarter since the industry began collecting statistics, according to the Robotic Industries Association. Spot welding and material applications fueled the big jump, states Donald A. Vincent, executive vice president of RIA.

"The spot welding surge reflects the continued demand in the automotive industry, while the jump in orders for material handling robots reflects increasing use in a broad range of manufacturing industries," he explains.

Other reasons why robot use is on the rise: They're fast, don't get tired, and are consistently accurate. They can also perform repetitive or hazardous tasks that human workers would have to do otherwise. And newer robots are becoming easier to program, with more sophisticated controls, and are more reliable than their predecessors.

Welding robots
In metalworking, especially in the automotive industry, robots rule in arc and spot welding applications. Although they don't have the abilities of a skilled human welder, they can quickly lay a bead or spot weld, running unattended in a production line. In addition, their combination of accuracy and repeatability is hard to beat.

The metalworking industry has no shortage of robots for welding applications. One of the newest was recently unveiled by Fanuc Robotics North America Inc., Rochester Hills, and The Lincoln Electric Co., Cleveland.

The Arc Mate 50iL is a six-axis compact robot that has the fastest wrist-axes speeds in its class, according to its manufacturers. A modular, electric servo-driven robot designed for arc welding, the system can be mounted upright or in an inverted position with no modifications. In fact, the robot has a double-jointed design, an advantage in overhead welding applications.

The robot can be used with the new R-J3 robot control, which is compatible with standard Fanuc robotic software.

Robotic cells are also becoming popular, combining robot, control, enclosures, and more into turnkey packages. One new unit is the WorldLite-52, from Motoman Inc., West Carrollton, Ohio. The company designed the system as a low-cost, compact cell for welding small parts.

Set up on a common base that measures 55 66 in., the WorldLite-52 includes Motoman's SV3 robot, MRCIIs controller with menu-driven arc welding software, integrated MIG welding package, stationary welding table, operator interface, and safety equipment. The fully articulated, six-axis SV3 robot weighs less than 70 lb and has a 6.6-lb payload capacity, 26.6-in. reach, and ±0.001-in. repeatability.

The system's partitioned table creates two welding stations, each measuring 26 44 in., to reduce robot idle time. The integrated welding package includes a Motoman Tough Gun torch, power source, wirefeeder, and a welding interface.

A proven performer from ABB Flexible Automation Inc., Fort Collins, Colo., is the FlexArc robotic arc welding cell. Mounted on a compact, modular pallet, it features an IRB 1400 arc welding robot, selected Orbit positioners, air or water-cooled welding torches, choice of welding supply, perimeter fencing, and light beams.

The IRB 1400 is an easy-to-use, six-axis robot with a slim upper arm design for good maneuverability. It has an 11-lb handling capacity and a 56.9-in.-radius working envelope. Position repeatability is ±0.002 in.

ABB and Miller Electric Mfg. Co., Appleton, Wis., have been partners in providing automated welding solutions to the metalworking industry. Miller just introduced a robotic welding source that will, no doubt, be a part of many ABB packages in the future.

The Auto Invision incorporates Miller's Invision 456P wire-welding power source with its Robotic Interface II. The "one-box" solution eliminates external cabling and connectors between a power source and a robotic control. It also features wire sharpening at the arc stop for consistent starts — necessary for frequent start/stop applications that require weld repeatability.

In the area of spot welding, Nachi Robotic Systems Inc., Novi, Mich., demonstrated a six-robot cell at the recent Robot and Vision Show. Two SF166s, two SG160Rs, and two SG160Ps worked in a half-size welding station that simulated a shorter production line.

The cell employed a new servo-gun technology that synchronizes guns to robot motion. The result is that the cell welds 25% faster than conventional systems. It also used high-speed interference detection software, which senses collision situations in less than 50 msec.

Of the six robots, the SFs are the newest. Making quick, short-pitch movements that speed production, the robots are lightweight and take up little space.

Material handling and parts transfer
Robots offer a number of advantages over human workers when it comes to material handling and parts transfer. Besides saving workers from doing repetitive and sometimes hazardous tasks, robots have the flexibility, precision, and capability to handle parts — whether delicate or heavy. In parts transfer, not only can they run unattended, but they don't take up a lot of floorspace.

For instance, Motoman's six-axis SK16 robot, which can be used for welding and cutting applications, also loads and unloads machine tools or presses. It has a payload capacity of 35.3 lb, a maximum reach of 61.22 in., and repeatability of ±0.004 in.

The slim design of the robot reduces interference areas and improves part accessibility. Part of its compactness comes from its Sigma series AC servomotor.

The robot is controlled by Motoman's 32-bit, RISC (reduced instruction set computing) architecture MRC control, which offers menu-driven, application-specific software. An ergonomically designed programming pendant is included with the MRC and features a 12-line, 40-character liquid crystal display.

Panasonic Factory Automation Co., Franklin Park, Ill., has come out with the VR-H series of handling robots, available in 8, 16, 32, and 120-kg payload-capacity versions. The robots tackle material handling, machine loading/ unloading, and metal-removal operations such as grinding. Each is easily programmed to correct its motion according to the forces encountered. For example, in the case of a misaligned part, another robot may attempt a required motion, but error out, overload, and shut down. The flex servo, on the other hand, will modify the motion of the VR-H robots to eliminate an overload situation.

In the past six months, Fanuc Robotics has showcased two new robots at machine tool shows. The first, the LR Mate 200i is a six-axis compact robot that performs intricate tasks while lifting parts that can weigh nearly 7 lb.

The LR Mate 200i, like many other Fanuc robots, has a modular-build, electric servo drives, and an R-J3 control. In addition, it can be mounted in upright or inverted positions. Fanuc also makes a longer-arm version of the robot, the 200iL.

The company also debuted a family of overhead rail-mounted robots, the first six-axis, top-loading robots in North America, says Fanuc. Three models, the M-6iT, M-16iT, and M-16iLT, provide a variety of reach and payload capabilities.

Melroe Co., manufacturer of the Bobcat Skidsteer Loader, was among the first companies to use the M-16iT. According to Beth Nelson, manufacturing engineer at Melroe, the M-16iT will replace two robots in a cell with a two-lathe application. She says it will also free up floorspace, only requiring room for two support legs.

The robots in the new family have six axes of motion — one linear and five rotary — which let them service multiple machines, stations, or operations. In addition, the robots have the dexterity to re-orient parts between operations as well as service both vertical and horizontal machines.

The rail mount permits top, front, or side entry into a machine tool and lets the robot reach behind itself to provide a 3D work envelope. Traditional gantry robots only offer a 2D work envelope and require more floorspace and ceiling height, says Fanuc.

The company also plans to introduce an Arc Mate 120iLT rail-mounted arc welder.

Robots that cut
In the cutting arena, robots are usually found wherever applications require close tolerances and fast cycle times. Robots are well-suited to high volume cutting and prototype work due to their flexibility and minimal tooling costs.

At the robot show, Motoman integrated its new ProfileStar two-axis enhanced profiler for cutting squares, circles, slots, and other holes into an SK45A laser cutting robot with CO2 laser. The robot has a maximum reach of 70.35 in., repeatability of ±0.006 in., and payload capacity of 99.2 lb. Motoman says the robot's slim base, waist, and arm reduce potential interference areas.

The profiler makes small, intricate cuts with no movement from the robot's other axes. Holes and shapes larger than 180 mm, on the other hand, use the other axes. The system also includes a predefined library of circle, square, and slot cuts that lets the robot cut using only one required point.

From ABB comes the IRB 2400 series of six-axis robots, the 2400L, 2400/10, and 2400/16. These systems have handling capacities of 11, 22, and 35 lb, respectively, with working envelope radii of 70 in. for the 2400L and 59 in. for the 10 and 16 kg models.

Antique Auto Sheet Metal, which makes sheetmetal components for antique cars, has been using an IRB 2400 robot since 1996, when it replaced hand-trimming operations with the robot. Before 1996, the company would die stamp a body panel, then finish-trim it. Hand finishing took 40 min, with employees rough trimming a panel, marking it, and re-trimming. Oftentimes, workers repeated this process until the part met spec.

Now, the robot plasma cuts the panel once, in just two min. The robot moves inside and under-neath the complex body panels without missing a beat — it cuts at about 40 ipm on 20 gauge and 80 ipm on 16 gauge. Besides speeding production, the robot has also improved part quality.

Jobshop opts for robots

One of Pressed Metal's operators programs the Panasonic PerformArc 100 robot welding cell using a teach pendant.

After analyzing their competitive market, Michael and James Atherton, vice president and president, respectively, of Pressed Metals Corp., Waukesha, Wis., decided they needed to expand their welding capacity. "We are a modest size contract manufacturer and jobshop offering a wide variety of metal fabrication services," says Michael. "Recently, our customers have increasingly asked for secondary operations, such as welding."

Adding more manual welding operations was too costly and the local availability of skilled welders was limited. So, Pressed Metals purchased a preassembled robot welding cell manufactured by Panasonic of Franklin Park, Ill.

The Athertons used the following selection criteria: economics in a jobshop environment, local technical support, ease of operation, worker safety, training complexity, and return on investment (ROI).

In addition, the company didn't want to integrate separate components from different sources. "The PerformArc is totally preassembled and all components were delivered prewired and fully integrated. Thus, we did not need to plan, find, and integrate other manufacturers' components," says Michael. "The cell is supplied with Panasonic products, for example an artificial intelligence inverter power supply, which is integrated with the 5-kg, C-controlled robot, plus a 60-in. turntable. All are designed to work together and weld rapidly."

Setup was quick; the company moved the cell in with a forklift, set it in place, and wired it up. Within a half-day, the cell was ready to weld.

A novice operator was able to program and set up the robot cell within 1 1 /2 days. "Programming time is dependent on the job and weld variables," explains Michael. "But, we only program a job one time and save it in memory for future use. We also purchased uploaddownload software, which lets us back up the programs from the computer in the robot to a laptop, if we ever have a system crash. We can restore all of the programs in the robot in a few minutes if required."

Jim reports that operators easily set up and enter operating settings, including welding parameters such as wire diameter and shield gas, through a user-friendly teaching pendant.

So far, production is up 400% to 500%. In addition, the integrated nature of the work cell, which incorporates the HM-350 artificial-intelligence power source, eliminates weld spatter problems. This, in turn, leads to a better quality product.

Carmaker adds more robots

The rear rails and ladders for the LH car are welded together as floors are shuttled in for join-up at DaimlerChrysler's Bramalea, Ont., facility. The automaker is using Nachi robots in a DCT Systems' integrated cell.

With the help of DCT Automated Systems, DaimlerChrysler has installed robots at its Twinsburg, Ohio, and Bramalea, Ont., plants to speed production and streamline operations.

In the Ohio facility, DCT and Fanuc Robotics teamed up to provide a high speed dual-robotic destacking system that feeds full bodyside apertures and other blanks to a new A-size crossbar transfer press.

The destacker system modules, which include Fanuc's M-410i/HW dual robotic stacking heads, an indexing conveyor, a blank washer, an idle conveyor, and a centering station, continuously process sheet-steel blanks that weigh up to 104 lb at the rate of 14/min. With a maximum capacity of 550 lb, the destacker can handle any blank the automaker processes. In fact, DCT equipped the robots with automatic quick-change tooling arms so that any number of panels can be produced.

The robot takes blanks off a cart, with the first blank removed in slow motion to en-sure everything is positioned correctly. If it all checks out, the robot moves into production mode, loading a blank onto the index conveyor every 8.5 sec. With both robots going, the system handles 14 blanks/min.

The robots are interlocked so that while one is placing a blank on the index conveyor, the other waits in a "pounce" position, ready to initiate its cycle. If either robot goes out of commission, the other one can work independently.

DCT also developed and built the entire underbody system for Chrysler Canada Ltd.'s LH vehicle. The system joins 72 loose parts with 1,740 spot welds and turns out 85 jobs/hr. It uses 214 Nachi robots and 24 operators.

The six-axis robots are all either SA-160 or SA-200 units. The SA-200 robots feature an AC servo, swivel of ±150° of motion on the arm, wrist rotation of ±360°, and bend of ±125°.

The LH underbody consists of three main subassemblies: front ladder and floor, the front structure, and the rear ladder and door. These subassemblies are brought together in a join-up station prior to moving to a final assembly line for underbody framing and re-spot. They are clamped together and spot welded, then moved to final re-spot welding operations.

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