Industrial PC Serves as PLC, CNC, HMI
Industrial controls and associated equipment, of course, include some of the most significant investments machine builders and manufacturers make. Naturally, the best control equipment requires the best electrical enclosures for protection from harsh plant environments. As the first line of defense from dust, moisture, and contaminants, the difference between a secure, high-quality electrical cabinet and a cut-rate one can make a considerable difference in maintenance efforts and uptime.
One of the primary qualities of a high-end electrical cabinet is its seal or gasket. There are multiple types of gaskets, and one of the most reliable types is the “foam-in-place” (FIP) gasket, made with high-quality resins, such as polyurethane. Seal Tech Industries, based in Chanhassen, Minn. (near Minneapolis), provides FIP polyurethane gasket technology for manufacturers. The company’s machines are used in a variety of markets, including the electrical enclosure, filter, and medical industries.
Seal Tech equipment is designed to dispense two-part polyurethane in any profile customers require. Meeting customers’ expectations for cost-effective solutions is obviously a top priority.
“Seal Tech machines are competitively priced, yet they still offer exceptionally advanced functionality,” explained Frank North, V.P. Machinery Division, Seal Tech. “User-friendliness is also critical—our operator interface is designed to be very intuitive, keeping the learning curve manageable even though our machines utilize cutting-edge automation technology.” The latest Seal Tech machine design incorporates all the lessons learned in more than 20 years in the industry to create an affordable, top-of-the line machine that makes polyurethane gaskets an affordable option for electrical cabinet manufacturers.
Recalculating the calculator
Latest Seal Tech innovations include the STI 8400 machine, with a new rinse recycler that makes it easier to change solutions that are used to purge the polyurethane in the mixing head after creating the FIP seals. This eliminates the need for reservoirs near where the machine does the dispensing. The rinse recycler reservoir is in a more convenient location with an “automatic dump” functionality.
Perhaps the most important function of FIP machinery is to ensure that the mix ratio of polyurethane ingredients is dispensed at precise outputs. “Seal Tech was the first in the industry to introduce an integrated scale that helps the machine operator ensure that foam mix ratios are correct,” North said. The integrated scale automates most complex calculations machine operators normally perform.
“These processes, which previously took 15 to 20 minutes, have been reduced to mere seconds,” North remarked. “Users simply enter in the machine ‘shot time’ and the mix ratio; the machine then tells the operator what the desired output is.” With the simple press of a button, the scale sends the finished calculations up to the HMI. By hitting ‘calculate,’ the machine determines the percentage of difference; by hitting ‘adjust,’ the machine automatically adjusts pump speeds for the user, giving operating convenience a substantial boost with easy-to-use buttons on the HMI.
This functionality was implemented via new HMI software. All system software and the scale are run on one hardware device, an industrial PC (IPC), North said.
On the STI 8400 machine, Seal Tech implements 20 cabinet-mount IPCs, with Intel Core2 Duo processors. The IPCs are connected to economy control panels with 15-in. touchscreens for the industrial display hardware.
Seal Tech ensures the ability to troubleshoot machines anywhere from headquarters facility or home offices. This helps to immediately remedy many problems without lengthy downtime for customers or excessive travel for Seal Tech support staff. Remote connectivity and troubleshooting is facilitated via the IPCs, using EtherCAT as the machine network, and WebEx services.
“Customers have total control in security and access to their machines,” North explained. “Once Seal Tech has been granted access, we can troubleshoot the machine program, or we can watch customers operate the machine and examine all parameters. In this way, we can see if anything is out of the ordinary and what could be improved based on what the machine is doing in real time.”
Seal Tech usually designs its FIP machines with wireless connectivity, enabled by a dongle. This dongle is given to the customer’s plant supervisor so the machine is connected to the Internet only when the customer wants it to be.
The multicore IPC “enables me to add a much wider range of peripheral devices than PLCs, such as the scale, and integrate them directly into the system easily and cost-effectively,” North said. The main advantage, North said, is that the PC-based control system integrates all machine control elements—the PLC, CNC, HMI, and other functions—into one industrial PC.
The IPCs on the STI 8400 machines run PC-based CNC software for the automation, which covers classic CNC path control, including high-end systems for complex motion and kinematics. The software can operate up to 64 axes/controlled spindles that can be distributed across up to 12 CNC channels. In a CNC channel, up to 32 axes can be interpolated simultaneously, allowing the software to handle the most difficult motion tasks.
Seal Tech received technical assistance from the automation provider for implementing the CNC portion of the machines.
North said he “had a good handle on” the PC-based PLC programming but took additional training courses focusing on IEC 61131-3 Structured Text programming from the automation provider.
The software controls the motion of the STI 8400 machines’ dispense heads and the servos that drive the polyurethane component pumps and the mixing motors. EtherCAT-based drives, servo motors, and planetary gearboxes actuate the motion control.
The system uses I/O modules with IP67 protection to facilitate machine communication.
“In addition to industry-leading performance, exceptional diagnostics capabilities, and fast communication speeds, the EtherCAT I/O system saves me considerable time wiring Seal Tech machines and makes them easier to troubleshoot,” North said. “In addition to simple Ethernet and Internet connectivity, one Ethernet cable connects most of the EtherCAT I/O to the control cabinet, eliminating junction boxes and the need to run cables individually. Also, the moisture- and dust-resistant EtherCAT Box modules can be installed on the machine in areas where it’s not practical to install another electrical cabinet.”
Foam-in-place machines, budget
Through Seal Tech’s efforts to use advanced PC-based and EtherCAT technologies, high-end FIP gasket technology is available at more affordable prices to electrical panel manufacturers.
“Cost-effective PC-based control enables me to offer a dynamic machine that can succeed against the competition at a fraction of the cost,” North said. “In some cases, Seal Tech machines can cost $100,000+ less than competitive solutions while offering the same or better functionality. This is a result of several factors that include Seal Tech’s low company overhead, ultra-efficient machine design, and automation; however, control system selection is an extremely important part of it.”
Contributing to the efficiencies, Seal Tech has also quantified significant wiring reductions by “not having to wire I/O to terminal strips and field devices to junction boxes,” North explained. “This also helps eliminate costly wiring mistakes. We estimate that we’ve saved between 20 and 30 hours of wiring time from our build process.”
Perhaps the greatest benefit has been in reliability. “We haven’t had a single Seal Tech machine failure in the field due to a malfunctioning” device or component from the PC-based automation provider, North said. “I know my machines perform and thrive once they are placed in the field.” Today all Seal Tech machines use the new controls, even for the company’s in-house gasketing business. “We have delivered a consistently high number of these new STI 8400 systems in 2011, and we are already backlogged for orders into 2012.” The new machines will use the new CNC controls and EtherCAT, North said. A large number of orders provides evidence that the new price-to-performance ratio strongly resonates with electrical cabinet manufacturers. As a result, more manufacturers can afford to better protect their electronic capital investments from the many perils of the plant floor.
– Shane Novacek is marketing communications manager, Beckhoff Automation. Edited by Mark T. Hoske, content manager, Control Engineering, CFE media.
Technologies details inside Seal Tech machine redesign
Recipe functionality was implemented via InduSoft HMI software. “All system software and the scale are run on a single hardware device, an industrial PC from Beckhoff Automation,” North said.
On the STI 8400 machine, Seal Tech implements Beckhoff C6920 cabinet mount IPCs, which feature powerful Intel Core2 Duo processors. The IPCs are connected to Beckhoff CP6902 “Economy” Control Panels with 15-in. touchscreens for the industrial display hardware.
Remote connectivity and troubleshooting is facilitated via the C6920 IPCs, EtherCAT as the machine network, and WebEx services.
“The multi-core C6920 IPC enables me to add a much wider range of peripheral devices than PLCs, such as the scale, and integrate them directly into the system easily and cost-effectively,” North said. “Of course, the main advantage of the Beckhoff PC-based control system is that all machine control elements—the PLC, CNC, HMI, and more—are integrated into a single industrial PC.”
The Beckhoff C6920 IPCs run TwinCAT CNC software for the automation, classic CNC path control, and high-end systems for complex motion and kinematics. One of the highest performance software platforms from Beckhoff, TwinCAT CNC can operate up to 64 axes/controlled spindles that can be distributed across up to 12 CNC channels. In a CNC channel, up to 32 axes can be interpolated simultaneously, making TwinCAT CNC suitable for even the most difficult motion tasks.
Seal Tech received technical assistance from Beckhoff North American support for implementing the CNC portion of the machines.
“We already had a good handle on TwinCAT PLC programming, but I personally took TwinCAT CNC training courses with a particular focus on Structured Text programming from Beckhoff at the company’s North American headquarters location in Burnsville, Minn.,” North said.
TwinCAT CNC controls the motion of the STI 8400 machines’ dispense heads as well as the servos that drive the polyurethane component pumps and the mixing motors. Here also, AX5000 EtherCAT drives, AM3000 series servo motors, and planetary gearboxes, all from Beckhoff, are used to handle the motion control.
Since the STI 8400 motion system is optimized for EtherCAT, matching high-performance EtherCAT Terminal I/O and EtherCAT Box I/O modules in IP67 protection from Beckhoff facilitate machine communication.
Reliability is high. “We haven’t had a single Seal Tech machine failure in the field due to a malfunctioning Beckhoff device or component,” North reported.
Today all Seal Tech machines use Beckhoff controls, even for the company’s in-house gasketing business. “We have delivered a consistently high number of these new STI 8400 systems in 2011, and we are already backlogged for orders into 2012. These machines will all be equipped with Beckhoff CNC controls and EtherCAT,” North said.