By Jim Montague, Executive Editor
The show must go on. In manufacturing, this means keeping your machines and production lines up and running no matter what. And, if you compete globally and export machined parts to Asia, Europe—or anywhere else for that matter—then it's a good bet your customers aren't very concerned if you can't get support for the machine that makes those parts. If you can't deliver, they'll just find another supplier.
This was the challenge facing T&L Automatics (www.tandlautomatics.com) in Rochester, N.Y., which makes 60 million to 80 million precision-machined parts per year, usually with complex features and intricate details for manufacturers in the automotive, aerospace and defense industries (Figure 1). The company started as a screw-machine shop in 1974, and later added CNC lathes and transfer machines, which move parts around within work cells. T&L can machine 1/16 to 7 in. square parts—about 85% of which go to automotive manufacturers.
To achieve required precision and productivity levels, T&L Automatics had to improve the capability, reliability and output of its machining centers. For example, the original control systems on its six Imasflex seven-station, dial-index machining centers were experiencing frequent shutdowns and significant downtime at least once per week. Also, the maintenance contract fees to correct control problems were costing T&L tens of thousands of dollars per year.
"The machine builder no longer had a presence in North America, so they weren't available for support or repairs. We were on our own, and so we basically had to become our own machine builder," says Tom Hassett, T&L's president and CEO. "Still, we run these machines every day, so we know their individual circumstances. It also helps that we're not afraid to try anything."
To Pick a Partner
T&L met with local system integrator Unique Automation (www.uniqueautomation.com) of nearby Palmyra, N.Y., and together they decided to retrofit T&L's Imasflex centers by replacing their old, problematic CNC controllers and hard-to-maintain, point-to-point wiring with Mitsubishi C64 CNC controllers, Q-Series programmable automation controllers (PACs) and operator interfaces—all tied together with CC-Link (www.cclinkamerica.org) networking. Hassett adds that Unique Automation wrote the software for the controllers, and T&L's own IT staff can add to their ladder logic programs as needed to provide index-on-the-fly, run-in-parallel or other functions.
"We're always seeking new capabilities and ways to reduce costs," Hassett explains. "In engineering meetings, and sometime even when we're quoting a project, we'll ask ourselves if we can get some new performance, and then we'll test it. Customers just look at the parts they want, and so we figure out the fastest and best ways to do it. If that means changing a standard machine into a specialized one, we'll try it. About 80% of our projects have some special task in it. Since about 2003, we've seen the U.S. manufacturing base shrink, but we didn't want to be blown away, and so we constantly innovate to stay ahead. We try not to raise part prices, so we try to offset increased expenses by being more efficient and productive. Not all ideas work, so we rethink, retry and just keep digging."
Two Networks Better Than One
The upgraded Imasflex machining center consists of seven machining stations, each with an X, Y and Z axis, as well as a spindle control (Figure 2). An eighth station is used by the operator for loading and unloading. To add CC-Link to the machining center, Unique deployed the PAC with two CC-Link master stations to control two independent CC-Link networks.
"This CNC controller is more capable because it can run two machining stations from one CNC controller, and then the PAC acts as the traffic cop between the CNC controls, other machine controls and the operator interface," says Joe Gerbig, Unique's owner and operations engineering manager. "CC-Link allows us to have our local and compact I/O at each station, and only run one common cable back to the PAC. This gave us huge savings in material and labor. The only long-haul wiring left is for servo motor power and feedback cabling back to amplifiers."
The first CC-Link network includes four CNC controllers to manage the seven machining stations. Each controller is a local station device and occupies four CC-Link network stations. Three CNC controllers manage six machining stations having X, Y and Z axes and spindle control for a total of 24 axes of control. The fourth CNC controller manages the seventh machining station with four axes of control. So the first CC-Link network serves a total of 28 axes of movement. This CC-Link network handles more than 1,000 I/O points for communicating status to the four CNC controllers as well as transmitting commands to control other functions of the machine.
The second CC-Link network consists of 24 remote I/O modules to handle the various inputs and outputs on the Imasflex (Figure 3). This second network connects more than 600 inputs and outputs to manage the actions necessary to machine complex features and intricate part details. These I/O include pushbuttons and selector switches for machine operation, pneumatic valve manifolds to control tool and part manipulations, tool changer inputs, over-travel/home switches, cooling pumps/valves, lubrication systems, hydraulic systems, and chip removal and filtration systems, as well as various outputs and indicators.
Less Cabling, Faster Performance
Even though its machining centers now have two CC-Link networks, upgrading from hardwiring to CC-Link still allowed T&L to eliminate about 8,000 ft of wiring per machine—down to 17,000 ft from 25,000 ft (Figure 4). Before the retrofit, broken, loose and shorted wires caused much of Imasflex's problems and downtime. Diagnosing mechanical problems and adding new I/O points is easier and faster now because CC-Link connects the remote I/O stations to the PAC and interfaces. Multi-axis, high-precision machining is delivered by the CNC controllers that are connected to the PAC via CC-Link.
"It's much easier for us to manage operations problems now," Hassett says. "In the past, we'd see there was a fault in the machine, perhaps from a proximity switch down inside, but we'd have to guess where the problem was located. Now, our Q-Series PACs and CC-Link network lead us right down the path and point to the problem."
Thanks to the retrofit, T&L also was able to cancel its maintenance contract with the original control manufacturer, which saved much of its former maintenance fees. It's also been able to increase productivity by up to 20%. "Basically, the new controllers allow us to manage our machining better, and do more different operations at the same time," Hassett adds. "Running less linearly and more in parallel has allowed us to decrease our cycle times by 12-15 seconds per part to 28-30 seconds from about 40 seconds previously. That adds up to a lot of saved time and more throughput over the two 10-hour shifts we run four days per week."
Better Accuracy and SetUp
By using the PAC and the two CC-Link master stations, Imasflex's new control program can read all inputs and outputs on the second CC-Link network, execute the control program, set all outputs, and communicate with the four CNC controllers on the first CC-Link network. The total processing time for this entire control loop is typically 7.3 ms, which was a significant improvement over Imasflex's previous system.
Besides reducing costs and increasing productivity, retrofitting the Imasflex centers also tightened tolerances and improved the quality of T&L's machined parts. With the original CNC control system, circular interpolation was difficult to accomplish. With the new system, T&L can hold tighter tolerances, enabling them to produce a wider variety of products. "The new controllers also give us more finite positioning and better interpolation," Hassett says. "This means the surface of the parts is much rounder. Instead of looking like a staircase, they look like a smooth circle."
Likewise, to ease setup of Imasflex's CNC machining parameters, one CNC operator interface panel is used for all seven machining stations. This panel is easily movable on a circular track, so operators can simply position the panel adjacent to the station on which they're working. T&L and Unique used CC-Link in conjunction with the PAC to remap the operator interface panel's I/O to control any of the seven machining stations at the touch of one station-selection pushbutton. The remap also seamlessly connected the operator panel to the appropriate CNC.
In addition, T&L and Unique report, once they started the initial power-up sequence, the CC-Link networks were operational within hours, allowing the debug and commissioning phase to commence almost immediately without the need to diagnose any network-related issues. In fact, the retrofitted Imasflex was completely functional the first day they started the commissioning process.
So far, three of the Imasflex machines have been rebuilt. T&L and Unique are at work on the fourth and fifth, and plan a similar retrofit of one of T&L's Liberty transfer machines and other equipment. The first Imasflex retrofit has been operating for more than a year without one control system failure.