Automation Has Its Possibilities
Selecting the right system for flexibility
By Jim Lorincz
Manufacturers of every stripe—not just the large high-production shops, but contract manufacturers, including the so-called "mom and pop" shops—are benefiting from automation of their horizontal turning operations.
"Ten years ago, it was the high-production manufacturers who were adopting automation. For the last several years, even the mom and pop shops in the US are looking to automation as a way to compete in a global manufacturing environment," says Jeff Thomason, operations manager-turnkey, Hardinge Inc. (Elmira, NY).
There are a number of reasons:
- Global outsourcing has changed the mix of products, trending toward precision-engineered parts that even the smallest job shops can successfully compete in producing.
- The bar stock, sawed blanks, castings, and forgings are supplied closer to net shape with more accurate size and quality of finish, making them more consistent to handle in automated systems.
"Ten years ago, if you had draft angles on castings and a lot of irregular flash, or rough and porous surfaces, automation was difficult," says Thomason. "Having to remove more material meant that you had to do a better job of chip management in the machine tool and some applications might not even be considered for automation."
- Automating devices, especially robots, have become far more reliable, and users aren't intimidated by them as programming and improved performance have increased payback, raising their potential for manufacturers.
The challenge for manufacturers and their machine-tool suppliers and integrators of automation systems is to determine exactly what level of automation is needed in their turning applications and how best to achieve it.
"Our customers generally have some preconceptions about what is best for their process or application, so our biggest hurdle is understanding our customer's requirements, process flow, takt time, and any floor-space constraints that may influence the choice of automating system," says Thomason.
Automation for turning systems ranges from the simplest combination of bar feeder and parts catcher to gantry-mounted robots. "The magazine bar feed and parts extractor combination is automation in its most fundamental form, enabling the manufacturer to run untended and make parts with the least amount of human intervention," says Thomason.
At the next automation level, pick-and-place systems are effective for some dedicated applications, but they aren't easy to redeploy should the manufacturer have to change jobs. "We've had success with one that we use on our gang-tool lathes. It consists of simple devices that are mounted on the cross slides. We try to parallel the time in the process so that when a finished part is taken out of the spindle by the gripping system, the other gripper is in alignment with the part pick up point so that two actions result from one motion. The same things holds true on the other side. When we are depositing the finished part into the conveyor or gravity chute, the gripper is in line with the spindle centerline to load the blank part. We actually have achieved cycle times of slightly more than 3 sec, which is fast to load and unload a machine tool," says Thomason.
At the next levels of automation, manufacturers begin to benefit from the flexibility of gantry load/unload devices and robots. They conserve valuable floor space by having robots service a number of machines or moving material handling overhead with gantry loaders. The challenge with straight two-axis gantries has more to do with long-beam applications where multiple machines have to be kept in alignment in a single plane. Bumping a machine with the fork truck or causing a misalignment when changing gripper fingers can require time-consuming tweaking of the system.
The gantry-mounted robot, in Thomason's estimation, is at the top of the pyramid of automation choices. "The gantry-mounted robot is the most flexible because it's easy to add a machine or an operation as long as it's within the reach of the robot. All that is required is doing some programming and adding guarding if needed."
Because material handling is being done overhead with gantries and robots, work envelopes of horizontal CNC lathes have to be readily accessible. Machine access considerations figured prominently in design of Hardinge's RS-Series and SR-Series of horizontal turning centers. "The squared-off look had a practical purpose. We adopted a square canopy look for overhead loading with a gantry robot." Thomason explains, "We needed to increase the entry to the machine from overhead access and to increase the work envelope. We wanted to avoid having to open the operator's door for robots, which can impact cycle time, but it can become difficult to contain contaminants such as chips and coolant in the machine when you're changing parts."
Automation introduces another set of concerns as the operator is removed farther from the process. "The goal is to keep spindles running in a way that requires the least amount of manpower while maintaining good part quality," says Thomason. "In some cases, the more automation is introduced into the system, the more chance there is for error. You really have to review the process and determine what level of error-proofing is needed to protect not only the machine and the automation, but to avoid making scrap. You may need some vision systems or silhouette gates to make sure that parts are introduced into the system in the correct attitude, or postprocess gaging to compensate for tool wear."
Robots have long been regarded as an effective automation device for relieving operators from strenuous and even dangerous operations. Typically, when fatigue and other human factors are removed from such processes, production rates improve. Such was the case when Bardons & Oliver (Solon, OH) completed a robotic installation for Seidel Stahlrohr (Monheim, Germany), a supplier of DOM and CDS steel tubing for the hydraulics, printing, roller, automotive, cranes, and machine tool industries. In partnership with Fanuc Robotics America Inc. (Rochester Hills, MI), Bardons & Oliver provides robotic automation for its CNC lathes, cut-off lathes, and special CNC turning equipment.
The robot system was required to handle cylinder tube sections, which varied in size from 1.5 to 8" (38–203-mm) OD, 4–100" (102–2540 mm) long, weighing from 5 to 475 lb (2.3–215 kg). In spite of the large variety of part sizes processed, the system had to be designed to provide minimal process interruption due to changeover. Robot programming also had to provide flexibility to either process parts based on input of a preprogrammed part number, or based on input of specific part size parameters.
In addition to the heavy payload capabilities, the robot needed to have sufficient reach to unload two Bardons & Oliver CNC turning/cut-off machines and place finished machined tubes into racks. To address layout, reach, and process-rate challenges, a process simulation was created during the proposal-development phase of the project. The simulation was developed using Fanuc Robotics' HandlingPRO software and provided an accurate representation and validation of the final production system.
The total process solution provided by Bardons & Oliver included a Bardons & Oliver 36TBC CNC turning/cut-off machine and a robotic automation system based on the Fanuc Robotics M-900iB/350 robot. This equipment was integrated into an existing process line which included a second 36TBC.
The Fanuc Robotics M-9000iB/350 is a six-axis robot designed specifically for heavy payload applications, with a carrying capacity of 350 kg. With a reach of 2.66 m, it is well-suited for the Bardons & Oliver system layout.
The Bardons & Oliver-designed end-of-arm tool is capable of handling all sizes of tubing processed with no changeover requirements. Control is supplied by the Fanuc series 18i-TB controls and machine-to-robot communication is handled via the Fanuc I/O link, which allows total I/O access and flexibility.
The Fanuc Robotics R-30iA controller and iPendant provide the cell control and central interface for the robot system. The iPendant has a multiple window color display, which allows easy input and adjustment of system parameters and provides quick access to built-in diagnostic and help information. Custom user-developed screens and messaging, and the iPendant's ability to access specific work instructions and machine setups on the plant network maximize overall system uptime and productivity.
The operator positions empty tube racks in the proper location in the robot work envelope and confirms that both machine tools are set up for the production run.
Based on the production schedules, the system operator either enters tube size parameters into the Fanuc series 18i-TB controller or inputs a previously processed part number. The Fanuc controller initializes the 36TBC CNC machine, downloads necessary part and process information to the robot controller, and initiates the automatic cycle.
When automatic operation is in process, the Fanuc machine controls and the R-30iA robot controller communicates via the I/O link to monitor and control process flow.
Once the tube machining process is complete, the M-900iB/350 robot picks up the finish-machined tube from the machine output location. The robot then places the finished part into the appropriate rack and repeats the cycle until the production schedule is completed.
"Our philosophy is based on three key points, lean manufacturing, one-source responsibility, and modularity in configuration," explains Bill Gore of Fuji Machine America Corp. (Vernon Hills, IL). Fuji builds its machines for automation from the ground up. Machines employ built-in robotic automation, in-process auto gaging for quality control, and custom workholding, which is all supplied from one source.
"This allows Fuji engineers to guarantee takt time, cycle time, and Cpk with turnkey and run-off solutions that are built for lean manufacturing," Gore explains.
At IMTS, Fuji Machine displayed the production versatility of two twin-turret chuckers married in a cell with the HM-3000 milling cell, which is capable of five-face machining in one chucking for processing flanges, hubs, differential cases, among others. The PBS-300TT twin-turret chucker is capable of medium-to-high volume production with short cycle times, featuring four-axis simultaneous ID/OD diam rough and finish turning.
The PBS-300TT is equipped with Fuji's high-speed three-axis dual hand gantry robot with capacity of 6.6 lb + 6.6 lb (3 kg + 3 kg), conveying diam to 7 x 4.76" long (178 x 121 mm). The PBS-300TT operates a maximum spindle speed of 3000 rpm and generates 20 hp (15 kW) at the spindle motor. For improved chip flow, the machining position of the PBS 300TT is located directly above a large chip receptacle at the bottom of the machine. Chips drop straight down from the cutting zone onto the chip conveyor.
The HM-3000 features a Fuji high-speed gantry robot for simultaneous multiaxis movement to access the front, back, left, and right of the traverse axis. Control is supplied by Fuji's SP1 Max Robot Controller. A Fanuc 210i-MB CNC control is included. Tools are mounted in a circular arrangement. Axial and radial holders can be freely attached anywhere in the turret with tool capacity of six, ten, and fifteen tool stations.
Single and twin-spindle turning centers from Amada Wasino America (Rolling Meadows, IL) for automated turning of small parts that "fit in your hand" use integrated automation with application-specific solutions. Machines range from the five-axis Mi8 for machining complex parts to the general-purpose G-Series to the twin-spindle JJ3 lathe. The Mi8 five-axis turning/milling center is designed for complex, multiple-operation workpieces for industries such as medical and aerospace. The B axis delivers multiaxis functionality for flexibility. An integrated tool changer and auto loader make the Mi8 well-suited for die and mold applications for untended machining.
"Today's advancements, such as electric hybrids, hydrogen engines, new-generation diesel, and gas fuel injection systems require precision-engineered components," says Bob Malmen, chief operating officer, Amada Wasino. "The Mi8's multiaxis functionality makes it an extremely flexible solution for our customer's technological needs."
The twin-spindle, twin-gantry JJ3 turn/mill center is designed to deliver maximum capacity in the minimum amount of floor space. The machine's platform simplifies auto-measurement, bulk feeding systems, line applications, and other cell configurations for multiple applications. The machine center features a 16,000 lb (7257-kg) thermal displacement casting and 15-hp (11-kW) spindle and is available with an 8" (203-mm) chuck.
The J1 turret-type entry-level turning center is fully automated for rapid loading and unloading, delivering high accuracy turning with 0.00001" (0.0003-mm) resolution. "The J1 provides an economical option for job shops looking to expand or to large OEM manufacturers because of its automation," says Malmen.
In addition to bar feeds and robots and other automating systems, Hardinge's turnkey solutions include a novel way of moving parts to different machining processes or sequences of operations using specially equipped carts from Distech Systems Inc. (Rochester, NY). The systems feature a gantry with a robot and fixturing and trays to handle parts that are wheeled to the machine. One advantage is the flexibility to meet shop-floor reconfiguration while eliminating the need for hard-constructed material-handling belts and pallet conveyors. The Distech DS1100-MTL-TD is a compact machine tool loader for turning applications that can be set up next to any machine tool and feed parts directly from a conveyor or tray to the chuck, spindle, fixture, or the machine tool loader. The DS1100 can function as a mini workcell with the seven-axis robot loading or unloading auxiliary equipment. The robot can also transfer parts to secondary operations such as washing, inspection, or marking.
This article was first published in the October 2008 edition of Manufacturing Engineering magazine.