Automating for Productivity
Latest improvements in automation gear help manufacturers gain efficiencies
By Patrick Waurzyniak
Productivity on the shop floor depends on automating the factory. With the latest robotics and automation equipment, manufacturers are finding innovative ways to compete in today's tough cost-conscious markets.
Among recent automation offerings, new methods to compete with vision-equipped robotics, new controls software, enhanced factory-floor safety, and automated pallet systems hold some promise for manufacturers looking for an edge over the competition.
Robotic vision technology offering intelligent 3-D vision with tactile feedback can enable new applications for using robots in load/unload and assembly situations on the factory floor, according to Dick Johnson, general manager, material handling, FANUC Robotics America Inc. (Rochester Hills, MI).
The company recently demonstrated such an application at the 2005 Robotic & Vision Show last month with FANUC Robotics' M-16iB robot equipped with FANUC's new V-500iA/3DL laser vision sensor and FS-30 Force Sensor. The robot's vision sensor identified and located a robot cluster gear assembly from a tray, then picked up and assembled parts for the gear assembly.
"The demo shows a robot building robots," notes Johnson. "At the FANUC factory, there's truly an amazing amount of automation that occurs. This year, we thought we'd try something different. One of the paint robots that is built in Michigan is the P200, and we decided to show one of our robots, the M16iB, performing an assembly operation of the P200 gear case.
In assembly applications, use of robotic vision has lagged applications like load/unload and machine tending, Johnson noted. "One of the reasons is that we take for granted what a person can do. Of course, a person has 3-D vision, a person has dual arms, a person has a complete tactile feedback--he can feel a blind hole, for example."
Robots have had success in penetrating small-part assembly applications with smaller table-top SCARA robots using 2-D vision, he adds, but now 3-D vision-based robots are beginning to tackle larger-part tasks.
"What we're showing is the next generation," Johnson notes of the robot building a robot demonstration. "We're showing larger parts in 3-D assembly. Actually, we're tilting the case, so we're assembling it at an angle, and we're using two attributes of an intelligent robot. Number one, we're using a 3-D vision system, which allows you to either find the part to be assembled in 3-D space or it allows you to find the structure that the part is to be assembled to. But the key is that when you have 3-D vision, you can compensate for an inexact world."
Combined with 3-D vision, tactile feedback via a 6-degrees-of-freedom force sensor enables the robot to mimic human-like tactile capabilities, Johnson says. The robot accomplishes this "because it can sense force in the X, the Y, and the Z direction, but it can also sense moments about the X-Y-Z," he adds. "If someone put their arms around your waist and rotates you in the air, that's a moment. If you think about a valve stem or a shaft being inserted in the hole, when you insert it, you may feel some force in the positive Z direction, as you put it into the hole, the critical dimension is to find out which corner is binding. That's going to be transmitted not as a force, but as a moment.
"The robot performed a shaft insertion of a gear, into a bearing surface," Johnson says of the demonstration. "It did a second shaft insertion, and then it inserted a third gear which meshed first with the first gear, and then with the second gear. FANUC has made huge advances in five years, with 3-D vision and 6-degrees-of-freedom force sensing, and this is something that is going to make possible larger-part and 3-D assembly that was never possible before.
Vision system costs also have dropped markedly, adds Johnson. "It's also gotten to the point where standard engineers can find it easy to concept and apply. I have integrators that tell me that 40% of their robots are going out with vision, so it's becoming commonplace. Our 2-D vision system is $6000 at list price, and then you have to buy a PC, but it's surprisingly simple to program. One of the advantages of the FANUC vision is that we handle the interface to the robot and the calibration--we solve those steps for you."
Motion-control safety is always an issue for manufacturers, and new features in Bosch Rexroth Corp.'s (Hoffman Estates, IL) IndraDrive control system helps eliminate problems with operators turning off safety features at the control.
"What we're offering is safety on board with integrated safety for motion in the IndraDrive," says Rick Rey, IndraDrive and IndraControl product manager, Bosch Rexroth Corp. (Hoffman Estates, IL). "Typically in the machine, when you try to control safe motion, they have to go through a safety PLC and relays, and there's more delay time. There are more chances of operators trying to bypass a safety feature by tying up safety switches."
The latest IndraDrive digital controls now offer integrated safety conforming to the European standard, EN 954-1, Category 3, according to Rey. The safe-motion features are built into the hardware of the servodrive, he notes, that allow machine-tool builders to password-protect the system to remove any chance of operators altering the settings. "It's built into the drive, so that we have safe motion. It's an option that the machine builder can buy, and it comes with a safety circuit card that gets implemented into the drive. We wire the sensors to the card, to inputs directly to the microprocessor on the drive board."
"Once all safety gates are closed and then the drive is switched to normal operation, then you have full power and operation of the drive. If an operator tries to bypass the sensor, then the drive would null and give an error."
Software and services are becoming more important to machine-tool builders, according to Wolfgang Rubrecht, general manager, Siemens Machine Tool Business Unit (Elk Grove Village, IL), which recently introduced its Internet-based ePS Network Services for maintenance and service along with a new network-centric thin-client Sinumerik Solution line of CNCs.
With its next-generation ePS Network Services, Siemens plans to address customers' downtime issues more quickly through new Internet-based service that can be accessed by any machine tool equipped with Siemens' Sinumerik 810D, 840D, or 840Di CNCs, along with a Siemens PCU 50 industrial PC, Internet access, and a standard web browser. "The ratio of software in a machine tool will increase," Rubrecht says. "It's estimated that software probably will be responsible for 90% of all downtime."
The Logic Control Modeler from Delmia Automation allows digital validation of PLCs prior to installation on the factory floor.
The network-centric architecture of the new thin-client Sinumerik Solution line enables the controls to be effectively combined with Siemens' Sinamics drive technology, according to the company, to design standalone as well as plant-wide automation solutions. The system, which uses standard Ethernet and Profibus protocols for machine tool communication, offers users an open-architecture HMI/NC kernel, advanced communication protocols, a space-saving modular design, and scalable hardware and software options. In addition, for the first time Siemens is offering thin-client technology for operator input. The drives' communications system, called Drive Cliq, provides improved diagnostics and fast drive recognition via the electronic type plate.
Digital validation of PLCs used in factory automation offers controls engineers a new way to quickly program and validate machines and assembly lines in the factory. With the new Logic Control Modeler software from Delmia Automation (Auburn Hills, MI), manufacturers now have a new way of creating controls logic and validating the logic prior to implementing it on the factory floor, notes Delmia Automation's Chris DeForge. "There's two steps to this kind of engineering. One is defining the nominal behavior of a system, whether it's a single machine, or a line, or an entire factory. The second step is to actually create the program itself that'll carry out that logic for each and every device, primarily PLCs from various manufacturers."
The Delmia software offers engineers a 3-D environment from Delmia and its parent company, Dassault Systemes SA (Paris) with its V5 system, that allow the controls engineer to graphically define the nominal behavior of the equipment and then associate the behavior with the 3-D model, according to DeForge, enabling engineers to create a library of anything from clamps to conveyors to fixtures.
"We're bringing that notion of plan early, validate early, solve problems early, similar to what we've used in the PLM space, into the automation space," DeForge says. "It has tremendous value for the controls engineer and for the enterprise--virtually every manufacturing enterprise employs programmable logic controllers."
The system allows programming PLCs in a graphical environment, similar to programming for robotics, where an engineer is able to program without knowing a particular programming language, he adds. "Often, the enterprise deploys different brands of PLCs in the same facility that might use slightly different programming techniques," DeForge says, "but with this, engineers don't have to be concerned about that."
Moldmaker Automates with HSM
At Advance Mold and Manufacturing Inc. (AM&M, Manchester, CT), automated HSM systems allow the precision moldmaker to effectively compete with offshore companies in the cutthroat moldmaking market.
To speed its moldmaking efforts, AM&M recently added a fully automated HSM cell to help the manufacturer cut lead times. Housed in an 18,000 ft2 (1672-m2) section of its 30,000 ft2 (2787-m2) facility that it shares with its partner Vision Technical Molding (VTM), AM&M employs 65 people working two shifts, six days a week. AM&M builds approximately 200 molds a year, machining as much as 300 tons of material, ranging from stainless steel to graphite electrodes for small, highly accurate mold components. About 20% of AM&M's work goes next door to partner VTM.
"Competition from China is real and price is perceived as a significant factor," observes Steven Arnold, AM&M president. "However, the cost difference between a Chinese-made mold and our product can diminish quickly when you factor in time, quality, and service. We win on providing full speed service for customers who can't tolerate delays due to quality glitches, distance, and de-bugging, or who have urgent design change needs."
To meet customer demands, Arnold invested in state-of-the-art equipment and found highly skilled people focused on realizing the full potential of advanced technology. The shop handles a wide variety of work but specializes in complex precision components for automotive, medical, and consumer electronics. AM&M earlier this year installed two Mikron (Lincolnshire, IL) HSM 400 machines mated to an automated 10-position pallet system and the capacity to hold 90 electrode holders with robotic support. The three-axis, 42,000-rpm vertical machining mills each have automated tool changers capable of holding 68 tools. Both units have full probing capabilities with laser tool measuring and compensation. A robot from Erowa Technology Inc. (Arlington Heights, IL) changes pallets when workpieces or setups change. The system also automatically changes grippers when changing-out graphite electrodes.
Automation gives the new HSM cell its high throughput. Served by a robotic pallet system, the cell enables staging and set up during operation, extending the system's production hours with much of the process conducted unmanned. For maximum flexibility, the Mikron 400 machines each use automated toolholders that are capable of three-second tool changes. This makes it practical to economically use tools with short operating times, such as drilling, countersinking, and threading.
The new mold cell replaces two bed-type mills that struggled to keep up with production demands and quality standards. The equipment required hand-loading and extra operators. The moving weight and mass of the machine components compromised accuracy. Thermal creep, as the production room and equipment gained heat, required constant checking and compensation to stay true to specifications.
"With the new HSM cell, we've seen our capacity grow by nearly 300%," notes Vincent Brown, CNC electrode/high speed mill department manager. "We like what the new programming software has delivered too. The ability to change priorities, easily enter new jobs into the system, and remotely monitor operations achieved dramatic improvements."
Setup time has been minimized due to a high degree of integration between the Mikron 400's and the robot. Mold parts are being made in half the previous manufacturing time. The two mills are averaging a combined 240 production hours per week, much of it lights out. Accuracy and repeatability are significantly improved.
"We can put up to 100 electrodes of different shapes and sizes in the system," explains Brown. "The laser probe offsets the Z position and the machine does the rest automatically, untended. The new cell has made life so much easier compared to our previous electrode milling machines."
This article was first published in the October 2005 edition of Manufacturing Engineering magazine.