February 2010 / Volume 62 / Issue 2|
As the robots turn
By Alan Richter
| Integrated automation of turning centers can be the solution to meeting production schedules and profit goals.
Courtesy of Fuji Machine
Need a turning center operator but are hesitant to hire an additional worker? An integrated robot and associated automation equipment might just be the ticket for optimizing a part manufacturer’s turning, as well as drilling and milling, operations by keeping the spindles operating as much as possible.
Turned parts typically have short cycle times of 1 to 3 minutes, requiring an operator to be constantly opening and closing the machine’s door to load and unload parts, according to Ron Ehrmann, sales manager for Automation Solutions Inc., West Chester, Pa., a distributor of machine tools and automation equipment. “There’s a lot of hands-on time where he’s totally dedicated to that one machine,” he said. “He can’t do anything else, and then when he’s not there, that machine is not running.”
To overcome that situation, Automation Solutions offers the “Lean Machine” system from Ellison Technologies, which includes a Fanuc M10 robot with riser, robot controller, drawer unit and fencing. End users usually start with four drawers with a 150-lb. capacity for each drawer and a 20 "×20 " usable envelope with 6 " of spacing between drawers. The robot accesses a drawer by pulling it to itself, and drawers, which are manually loaded, can also be accessed from outside the cell.
In operation, the robot pulls a drawer out to pick up a part, feeds the machine and then places the finished part in a container or back in the drawer. “When you do have a repeat job, even if it’s for 25 pieces, it’s easy to load it up,” Ehrmann said. “You just pull the drawer out, load your parts, push it back in and the robot takes over from there.”
Ehrmann noted that the system starts at around $75,000 and can include a vision system, which costs $3,000 to $6,000, if parts require special orientation. Typically, users of Lean Machine cells have achieved a payback period of 2 years or less using the system on a one-shift basis.
The system sits on a metal skid so it can be moved to another location if needed. Although companies that machine various quantities of a host of different parts often feel automation equipment isn’t suitable for their operations, Ehrmann noted that job shops make good use of Lean Machine projects. “You have all these drawers, so you can have very small part runs, and you do your automation setups during machining time,” he said.
Automation Solutions primarily adds automated drawer systems to existing equipment because shops aren’t operating the vast majority of their machines at full capacity.Automating New
On the other hand, machine tool builder Amada Machine Tools America Inc. (formerly Amada Wasino America Inc.), Rolling Meadows, Ill., integrates the majority of its automation equipment with new machines. That’s partly because the comparative cost of the automation integrated into a new machine is substantially less than buying it and having it retrofitted, according to George Kowalewski, the company’s national sales manager.
Amada builds various automated turning centers, including 2-axis, gang-tool machines; 2-axis, single-spindle turret machines; 3-axis, twin-spindle lathes with live tooling; and 4-axis mill/turn machines available in single-spindle, single-turret and twin-spindle, twin-turret models. “The common thread throughout all of our products is the gantry loader,” he said, adding that the exception is the Mi8 machine, which uses a Fanuc LR Mate loader, a 5-axis robot.
Courtesy of Amada Machine Tools America
The 2-axis gantry loader uses Fanuc servomotors to control both programmable axes. “Because it’s an encoder-driven system, we can stop anywhere along the travel of our gantry loader and perform all sorts of operations, namely gaging,” Kowalewski said. Gaging to measure parts and to adjust for tool wear is often critical in an automated turning environment because scrap is created quickly when machining is not monitored.
He noted that 65 percent of Amada’s business is with automotive operations, which typically run 240 days a year, 22-plus hours a day. “They expect 95 percent machine availability time.”
Nonetheless, the equipment is suitable for turning shorter runs because the end-of-arm tooling, or gripper jaws, can be quickly removed, and the gripper jaws locate accurately through a key/keyway system with a keyhole-type arrangement for the socketed cap screws, according to Kowalewski. “By breaking loose a fastener and rotating it three times without having to remove the fastener, you’re able to slip the jaw up and off the key/keyway arrangement and replace it,” he said.
Kowalewski added that the Amada carousel-type part supply device is also quick-change. “We are demonstrating a complete part changeover in less than 15 minutes in our Schaumburg [Ill.] Solutions Center,” he said.
Not only are automated turning centers appropriate for small part runs, but they can also handle small parts. Amada has one Illinois customer that found it challenging for a human operator to hold and get the tiny workpieces into and out of the workholders without dropping them. “It was tedious and, with all that repetitive motion, they were concerned about operators developing carpal tunnel syndrome,” Kowalewski said. “We were able to put together bowl feeders with our automation equipment to pick up blanks and drop off finished parts.”
Courtesy of Automation Solutions
Sometimes turning center automation doesn’t involve a robot. That’s the case with EMAG’s inverted spindle design, which is an integrated, self-loading turning machine concept where end users do not need robotic handling devices, according to Peter Loetzner, CEO of machine tool builder EMAG LLC USA, Farmington Hills, Mich. “The core feature is the pick-up spindle, which travels outside of the machining area, picks up the part, brings it inside, does all the machining and unloads it all by itself,” he explained.
The inverted spindle is on EMAG’s VSC, SLC and VL series vertical pickup turning machines. Loetzner added that all moving automation parts and accessories are outside the cutting area and on top of the machine, which helps keep the machine envelope clean and maintenance free.
An end user could add a robot with a camera to take parts out of a bin and load them into the automation equipment, but if the parts are manually loaded into the carrier prisms, then the end user doesn’t require accessory robots or any other external components, Loetzner noted. In addition, the universal carrier prism design allows the machine to accept a range of parts without any changeover requirements or fixturing or palletizing of parts, according to Loetzner. If needed, inexpensive pilot pins or pallets of a simple design can also be used as a standard automation solution.One-Stop Shop
For machine shops that produce different products and must frequently change processes, it is helpful for automated turning to be modular, in that it can be reconfigured, retooled and reset for those different products. That’s the case with turning center automation provided by Fuji Machine America Corp., according to Bill Gore, regional sales manager for the Vernon Hills, Ill., machine tool builder. In addition to the machine, which includes the integrated robot, many peripheral devices, such as conveyance systems, work stoppers, workholding and auto gaging, are available. They are all designed and manufactured by Fuji, Gore noted.
Courtesy of EMAG
He emphasized that the Fuji MAX SP1 robot controller, which provides an interface between the operator, automation and machine, is separate from the Fanuc CNC for controlling toolpaths. Slaving off of the CNC limits the number of inputs and outputs an end user can use when adding peripheral devices in the future. “Using these two integrated controllers is a more efficient way to automate equipment,” Gore said. “You have the available inputs and outputs to handshake and communicate with that automated device that’s receiving your part. You can expand.”
How a robot loads a workpiece into a turning center is also an important consideration. Gore noted that a Fuji 4-axis-controlled swing arm robot provides more freedom to create a flexible manufacturing solution. The loader loads a workpiece underarm similar to how a human operator would. “We’re not lifting up over the chuck, dripping and leaving chips and swarf on key contact points,” he said, adding that the robot is conveying the part in front of the operator at eye level to avoid obstructing his view of the operation.
Although Fuji Machine serves the high-volume automotive industry, Gore emphasized that the company also serves eight-man job shops. “They need to automate to stay competitive,” he said.Reduced Labor
In addition to being able to accurately plan how many parts are going to be produced each day, shops benefit by being able to minimize or eliminate human labor and, potentially, the number of machine tools required with automated turning centers. Loetzner recalled one customer replacing four machines with one EMAG automated machine and calculated payback based on cutting the number of shift operators from 10 to three. After 3 months, however, the customer called to indicate his labor assumptions were incorrect. “I asked ‘what happened?’ and he said he was able to run the shift with two people,” Loetzner said, adding that payback will take 6 months. “Half a year is aggressive, but always within a year.”
He added that some customers operate equipment without operators for lights-out machining. “Operator intervention is rarely required.”
For the workers who remain, automation can enhance the lathe operating experience. Rather than manning one machine and performing the same tasks ad nauseam, an operator runs multiple machines and conducts varied functions. “It’s not uncommon for end users to have one operator running three, four, five machines. Tasks then change from taking parts in and out of the chuck and hitting cycle start to attending the part supply, placing finished product, doing inspection and those types of activities,” Amada’s Kowalewski said. “The operator-to-spindle ratio really decreases when you go to automation.” CTE
About the Author: Alan Richter is editor of Cutting Tool Engineering, having joined the publication in 2000. Contact him at (847) 714-0175 or firstname.lastname@example.org.
10 common mistakes when purchasing automation
Amada Machine Tools America Inc.
Automation Solutions Inc.
EMAG LLC USA
Fuji Machine America Corp.
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