Fifteen years is nothing when it comes to the life of a stamping press—at least for most of the press. Much of its structural components can last two to three times that long. But when it comes to drives and controls, 15 years is about it; time to breathe new life into the press with an electrical upgrade.
Refurbishment of this 2006-vintage 630-ton Mueller Weingarten transfer press, along with its servo transfer system and zig-zag feeder, included a complete press rewire and new electrical enclosures, replacement of the aging press control with an Allen-Bradley GuardLogix Safety PLC, the upgrade of 14 servo axes, and the addition of signature-based tonnage monitoring.
Such is the theme of this story, from automotive parts manufacturer Ernst Metal Technologies and its U.S. facility in Moraine, OH. Established by its German parent company in 2005, the company supplies parts and assemblies—primarily for transmissions and thermal-management systems—throughout North America. Its 100,000-sq.-ft. facility houses six large press lines, including a 2006-vintage 630-ton Mueller Weingarten (MW) transfer press on which we focus our attention here.
Revitalizing a Workhorse
The MW press has been a workhorse for Ernst since the plant started operations 15 years ago, turning out parts by the millions from mostly high-strength low-alloy steel sheet, 0.3 to 6 mm thick. But when press downtime, for maintenance purposes, became more than just a nuisance and began to impact production, management had to act.
“The ongoing issues with the outdated control on this press were impacting overall equipment effectiveness (OEE),” shares company vice president and sales manager Tuncay Onursal. “Lack of available spare electronic components for the press and control system became a significant issue, and we wanted to provide our operators and maintenance team with an updated press line that would enable them to be as productive as possible.”
The press-refurb project came to a head in November 2020 during a planned six-week window to shut the press down for its makeover. Partnering with Toledo Integrated Systems for the turnkey project, Ernst installed a complete control solution for the MW press, as well as its servo transfer system and zig-zag servo feeder. Toledo Integrated, along with a complete press rewire and new electrical enclosures, replaced the aging press control with an Allen-Bradley GuardLogix Safety PLC, “to run the press, transfer system and feeder,” explains John Eby, sales manager at Toledo Integrated. “We also upgraded two servo axes on the feeder—transverse and longitudinal—and 12 servo axes on the transfer system, including two for gripper-width adjustment, installing Allen-Bradley Kinetix servo drives.”
But wait, there’s more…much more. Included with the project is Ethernet communication to the PLC, safety I/O, HMI and drives; updated safety using Allen-Bradley Safety Point I/O modules; new servo motors; a new Allen-Bradley 275-hp main motor drive; Toledo Integrated’s PressWatch signature-based tonnage monitor, with 1-deg. resolution; “and, last but not least,” says Eby, “tying it all together for the operators and maintenance team at Ernst is a 19-in. Allen-Bradley PanelView control screen.
“While we don’t see many shops go with the large screen,” Eby continues, “the advantage can be tremendous. It gives the press operators and the maintenance team immediate access, on just a few screens, to all of the information they need for setup as well as for production and troubleshooting.”
What Makes a Good HMI?
While all-new motors and drives on the 630-ton transfer-press line work behind the scenes to optimize OEE, a 19-in. Allen-Bradley PanelView HMI improves operator efficiency and job satisfaction. From a maintenance perspective, the new control pinpoints faults immediately and provides all of the information needed to streamline troubleshooting.
When one vendor, in this case Toledo Integrated, manages an entire line upgrade such as this, it’s easier to ensure that the customer and its various work teams—production, maintenance, quality, etc.—get exactly what they’re looking for. In Ernst’s case, the custom HMI is exactly what the (press) doctor ordered. Some of those key HMI characteristics:
- Self-explanatory, intuitive and easily understood
- Information conveyed on the home screen based on input from the operators and their individual needs
- The large display, so as not to cram too much information onto one screen
- HMI graphics that illustrate the production process, to provide better visualization to the operators and maintenance technicians, giving them a sense of the action that’s required.
“The home screen includes all of the information the operator needs to know to ensure that the process continues to run per spec,” explains Ernst maintenance manager Jacob Crabtree. “That includes press tonnage, feed and press speed, and data on the hydraulic systems. And, prior to the upgrade the press lubrication system had its own independent control station. Now, that functionality is included in the new HMI and at the operator’s fingertips.
“From a maintenance perspective,” Crabtree continues, “with the original press control troubleshooting, an error message was often complicated and time-consuming. Identifying and locating faults could take hours. This new control pinpoints faults immediately and provides all of the information needed to quickly address them. We also can connect a PC to the control to look at the PLC files, greatly streamlining some troubleshooting efforts.”
Communication and Data Exchange
The control also communicates electronically with the Ernst proprietary, inhouse-developed machine-data-acquisition (MDA) system, which sends alerts to plant personnel when a press goes down. “From our phones or computers,” explains Crabtree, “we can monitor OEE and downtime codes as selected by the press operator. The MDA can generate reports, track uptime and downtime, hit rates, etc.”
Being that this press takes on mostly long-running jobs—it mostly runs eight dies, each for parts with annual production volumes of 800,000 to 900,000—press green-light time is crucial. And, there’s been a remarkable improvement in OEE already, just a few months after the upgrade.
“While it’s still very early in the operation of the refurbished press,” says Ernst Metal president James Burt, “we’re confident, just from an operator and maintenance perspective, that OEE has improved by at least 5 percent. And, we also know that our operators are much happier on the job and more productive. It’s greatly improved operator efficiency and job satisfaction.”
Now the Ernst Metal Technologies team has its sights set on another press-line control system upgrade—this one, slated for later this year, for an 800-ton transfer press. “Since we don’t have redundancy for that press,” Burt adds, “that project will pose more challenges. We’ll need to build up an inventory bank. We’ll complete that project in two phases—issue the purchase order for the control build and have it ready to go before we take the press out of commission.”
Metal Froming Magazine article / April 27, 2021 / Brad Kuvin, Editorial Direct