With advances in robotics and automation systems, innovative manufacturers spur shop-floor productivity
By Patrick Waurzyniak
Staying competitive in manufacturing demands the utmost in automation. To keep factories from moving offshore, manufacturers must invest in the latest technical advances in robotics, automation software, and conveyor systems to compete more effectively with low-cost producers.
Among the latest advances are robotic milling techniques, faster six-axis robots, and vision-based systems that enable new applications deploying robots in the factory. New factory software solutions aimed at increasing productivity on the shop floor, and the latest automated conveyor systems also are helping manufacturers boost their efficiencies.
Robotic milling holds promise for robotic rapid prototyping applications and for machining softer materials including aluminum, says Joe Campbell, director of strategic alliances, KUKA Robotics Corp. (Clinton Township, MI), a subsidiary of KUKA Roboter GmbH (Augsburg, Germany). "We're seeing this transition now where robots are being used for a lot of machining processes, in softer materials and prototyping. This is an area that was previously dominated by machine tools."
Production applications using KUKA robots for milling workpieces already have been done in Europe, Campbell says, and the first projects are currently queuing up in North America. Applications in Europe include milling a prototype of the front of the Spanish bullet train. The KUKA robotic milling techniques are aimed at robotic machining softer materials at lower precision, including cutting of aluminum to ±0.030 - 0.040" (0.762 - 1.02 mm), depending on the application.
"We think there's a crossover point on the technology, where the robot and the control structures are becoming precise enough," Campbell notes. "Robots are stiff enough, frankly, and the control schemes are delivering enough accuracy, too. Generally what we say is if you have either hard materials, like steel, or you have very, very high tolerances, then it's probably not appropriate."
For machining aluminum or materials including rend board or clay for prototyping applications, robotic milling works very well, he says. "We're lab-testing aluminum jobs right now," Campbell says, "and we'll have some in production here very quickly. It's modest precision in aluminum.
"It'll be process-dependent, and it also depends on how you're going to program," he adds. "If you're going to do taught points, obviously you're going to be much more precise. If you're doing complete offline programming from a CAD system, then we start dropping precision."
Programming the robots plays a key role in machining by robot, and to that end, CAD/CAM developer Delcam plc (Birmingham, UK) recently announced an agreement with KUKA to develop tools for its PowerMILL machining software that can be used with KUKA's control systems to more easily program robots for a much wider range of applications.
"We anticipate that the main applications will be in pattern-making and in trimming of composite components," says Peter Dickin of Delcam. "However, the technology can be used in any area where softer materials need to be machined to accuracies of tenths of a millimeter. While this does not match the tolerances possible with a machine tool, it can often be more than adequate for components that might be several meters in length."
Delcam's collaboration with KUKA will develop easy-to-use routines within the PowerMILL CAM software. "These routines can quickly generate programs for its robots that allow smooth machining of large components," Dickin adds. "Now that this development work has been completed, we will be working together to promote this new approach to large-scale machining operations."
Machining with robots makes sense in some applications due to the much lower cost of a robotic arm when compared to a full machine tool. "A robot's work volume, on a per-dollar basis, is a fraction of the cost of a machine tool's work volume," Campbell notes. "In a lot of cases, we see people doing big parts and doing relatively small machining processes on them, but these are big parts that wind up getting fixtured and tooled on a big machine tool at a very high capital cost, and a very low throughput.
"We have a couple of customers who swear they're going to go do some work on low-grade stainless, but we'll wait and see. What I've been telling people is, it's an unknown process. With a machine tool, you know how much material you can take off, with a given tool, with a given spindle and a given horsepower. That's well characterized, and we're not there yet."
Six-axis robots also are finding new niches for automating the factory, such as KUKA's lower-cost, shelf-mount six-axis robots that help save factory floor space. The full-size six-axis systems feature capacities to 60 kg and offer a reach of 2200 mm. "We're seeing growth of specialized kinematics, and we have this whole family of robots we call 'shelf-mounted,'" Campbell says. "They're actually designed to be hung on top of a machine, whether it's an injection-molding machine, or a die-casting machine, or a machine tool."
With its new AdeptViper line of six-axis robots, Adept Technology Inc. (Livermore, CA) recently expanded its range of articulated robots targeting a variety of automation and assembly applications. The AdeptViper robots feature increased speed and payload capacities for material handling, packaging, and testing applications.
"In general, companies are looking to keep manufacturing on-shore," says Tim DeRosett, Adept Technology's manager, six-axis business development. "In some of the areas where there's a high product mix, there's a need to minimize inventories, or have just-in-time deliveries. With high product mix and low inventories, fast changeover, or shorter product runs, are required. As a result, there is often a need to change over multiple times during a day, whereas in the past, it's been weeks or months on a product line."
Minimizing setups with a minimum investment is key as well. "In those types of installations and factories, robotics is playing a key role," he says. "In fact, we've done a number of projects where high product mix and low inventory is the driving factor. We're seeing that more and more, particularly in markets where manufacturing is done domestically." Improving quality and driving costs out of products also is essential, he adds, with innovations including shrinking the form factor of controls, and embedding controls into Adept's robots.
Vision-based robots have become critical to many applications, with better vision capabilities dovetailing into new applications for the systems. Adept recently introduced its new iSight vision guidance system designed to work with its Cobra i-Series SCARA robots. The iSight system enables the development and use of vision and guidance applications to be simpler and much faster.
"The vision system and the robot controller must be integrated to the point where they can share information quickly and precisely, and we do that," DeRossett says. "What Adept iSight does is provide integrated vision, and when I say integrated, the vision is actually running on the PC but it is tied together very seamlessly with our calibration routines to the robot controller. It's a very robust and capable object locator tool for locating objects that the robot can acquire or place."
Protecting the manufacturing base can be accomplished through increasing automation in concert with working more effectively through lean manufacturing techniques and Six Sigma methodology, notes Dick Johnson, general manager, material handling, FANUC Robotics America Inc. (Rochester Hills, MI). Moving manufacturing to offshore locations involves many hidden costs, he notes.
"The main idea behind our 'Save Your Factory' initiative is to focus on labor costs and also show the hidden costs of going offshore," Johnson says. "People should factor in those things when they're trying to squeeze out cost. One of the most important things we can do is think how to properly apply automation and robots. In order to be competitive, companies should do this as a process. I really think it has to be a corporate initiative."
At the recent FANUC Ltd. customer event in Japan, many new automation technologies were shown, including bin picking with an overhead camera for a rough find combined with a laser, Johnson notes. FANUC's V-500iA/3DV robot system uses a grayscale camera and produces a 3-D image.
Automation software also can help dramatically boost machining efficiencies by monitoring factory systems and manufacturers' Overall Equipment Effectiveness (OEE), notes Mark Brownhill, machine tool services manager, GE FANUC Automation Americas Inc. (Charlottesville, VA). GE FANUC's Proficy Machine Tool Efficiency (MTE) Shop Floor Intelligence software solution enables manufacturers to collect real-time availability, performance, and quality data from machine tools to analyze shop-floor performance.
"Our Proficy Plant application suite is good for monitoring the factory floor from the different elements, particularly from production, quality, and efficiency," Brownhill says. "It allows you to look at variation, genealogy, or anything related to quality-how a product got built, when it got built." The software suite includes three modules for discrete manufacturers, with modules for tracking quality, production, and efficiency, enabling analysis of the three areas including the full manufacturing process.
"On the CNC side of the business, you can customize and add more tools around the machine tool," Brownhill adds. "That's what OEE Machine Tool Efficiency is, a more fleshed-out, ready-out-of-the-box solution for the machine tool application. The other modules, production and quality, are just as relevant."
Updated conveyor systems from Bosch Rexroth Corp. (Hoffman Estates, IL) are helping manufacturers stay competitive with new designs for automation, assembly, and material-handling applications. In the past year, Bosch Rexroth introduced its next-generation TS4plus assembly conveyors, its Varioflow pallet system, and the company's new CMS-Cartesian Motion System.
With Bosch Rexroth's TS4plus assembly conveyors, modules include a redesigned lift position and lift transfer units. The new VarioFlow system now includes a pallet program, allowing the system to be used in assembly applications where traditional assembly conveyors are not the best solution.
"Our assembly conveyors are used in a lot of industries--medical device, communications, electronics, and especially in automotive, but in the last few years, we have seen assembly conveyors being used more in machine tools," notes Mark Dinges, Bosch Rexroth product manager, TS conveyors. "We're seeing increased demand for the purpose of part-flow management in and out of machining centers, and also for inspection."
This article was first published in the July 2005 edition of Manufacturing Engineering magazine.