- Aging batch control systems were obsolete and inefficient. And their lack of quality-control functions threatened the loss of a key customer
- FactoryTalk Batch – Control-and-information software brought greater automation and quality control to batch processes
- PlantPAx DCS – Modern DCS system replaced obsolete control systems and incorporated modern HMI practices
- Increased revenue – Greater batch automation has improved throughput and helped the plant improve monthly revenue
- Improved quality control – New quality-control functions have helped retain the key customer’s business
- More efficient operations – The new DCS system has put a stop to frustrating pop-up alerts and a new grayscale HMI has helped operators more quickly spot issues
- Reduced configuration time – The process objects library helped cut programming configuration time by about 40 percent
Upgrading obsolete controls has helped solvent plant improve throughput and quality control
Solvent Plant Scrubs Aging Batch Control Systems
The small but powerful semiconductors in our smartphones and other devices can take several weeks and hundreds of steps to manufacture. During production, cleaning solvents are crucial to maintaining a high level of purity in these small and delicate microelectronics.
DuPont’s small-batch production facility in Hayward, California, makes semiconductor cleaning solvents in dozens of varieties. But the batch control systems used in the plant started showing their age in recent years.
The systems were no longer supported. They were also creating production issues, such as pop-up alerts that frustrated operators and alarms that were difficult to manage. More importantly, a customer audit found that the systems lacked recipe-based automation, which could help improve quality control in the production process.
The plant was faced with a choice: upgrade the legacy batch control systems, or stay with the status quo and lose thousands in monthly business. The plant moved forward with the upgrade. And in doing so, it did more than improve quality control – it also helped improve the plant’s throughput to create new monthly sales.
Old Systems Limit Operations
Most of the legacy control systems at the Hayward plant were manually operated. Only the bulk addition of material from a storage tank to a blend tank was automated.
Operators manually added all other materials using a drum-pumping station and solids-conveying station. Operators also set the timing for the materials to blend and circulate through filters, and took product samples. Once the desired product was achieved, operators manually sent it to the filling systems in the packaging area. Here, workers dispensed product into packages that ranged from small 1- and 5-gallon containers to large 200-gallon totes.
These manual processes introduced the potential for errors. For example, an operator might intend to mix a material for 15 minutes but end up mixing for 18 minutes while they carried out another task. Instances like these created the potential for slight product variations.
The legacy systems were also at times disruptive to production.
“The HMI was configured in a way that it generated a pop-up alert every time we opened or closed a valve,” said Nancy Givens, an automation and process control engineering consultant for DuPont. “If the operator wanted to open three valves, they’d get three pop-ups. This was frustrating for operators. And it created opportunities for errors. Cluttered interfaces could result in operators opening or closing the wrong valves.”
Alarms were another issue. The legacy systems used a mix of user-editable and hard-coded alarm setpoints. The hard-coded alarms were difficult to manage, with operators often struggling to locate specific code. The alarms also didn’t use modern alarming best practices, such as the ability to assign alarm priorities.
These issues – combined with the customer’s demand for greater quality control – necessitated a control-system upgrade.
Phase One: Controls Upgrade
Givens worked with system-integrator TechKnowsion and Rockwell Automation, a DuPont Global Alliance Supplier, to plan and execute the controls upgrade.
The team carried out the upgrade using a two-phased approach. In the first phase, they replaced the batch system’s PLC and HMI with a PlantPAx® distributed control system (DCS). This involved reverse engineering the legacy PLC’s code to determine the requirements for new control code.
“We didn’t want to just duplicate or convert the code,” Givens said. “We went back to the functional requirements of the system to significantly clean up and improve the code. We then incorporated that code into our PlantPAx-based process objects library, which we have customized over the years to our specific needs within DuPont.”
The control system’s new HMI used modern visualization practices to give operators a better viewing experience.
“The legacy HMI used multiple colors that could create cluttered screens,” Givens said. “The new grayscale HMI highlights items in red to alert operators of critical issues. I’ve done spot checks on the floor since we implemented the new HMI, and our operators always know where to pay attention. They never miss a thing.”
Phase Two: Batch Automation
In phase two, the Rockwell Automation global solutions team worked directly with DuPont to configure and install FactoryTalk® Batch software to achieve full recipe control and sequential automation.
Givens and her team wanted to follow the ISA S88 standard, which lays out the framework for implementing batch systems. This required that Rockwell Automation first build a physical model of their production equipment and then create a procedural model of the automated production phases. These phases then become “building blocks” that can be interchangeably used for different recipes.
“Phase management features within batch software allowed us to explicitly follow the S88 standard,” Givens said. “This saved significant time. The team only had to configure a phase, such as mixing or addition, once. We could then reuse it multiple times. It’s much more efficient than creating new code for each recipe.”
The team also utilizes the batch software for manual processes, such as sampling and recipe reviews. The software provides manual phases that integrate with automated phases to give users a seamless operating experience between the two. “We widely use this feature across DuPont,” Givens said. “We find it easier and smoother to implement than writing manual-process code in the controller.”
Finally, the team worked with Rockwell Automation to install the software for tracking materials in the plant’s storage tanks. The software replaced the plant’s paper-based logging system, which required manual inventory tracking. It also incorporates automatic tank switching.
“Previously, if a tank ran out of material during an addition phase, operators had to track how much material was added and calculate the remaining amount needed from the tank,” Givens said. “Now, the software automatically calculates the remaining amount of material needed, switches tanks, and adds the required amount of material until it reaches the setpoint.”
A Big Boost to the Bottom Line
The new automated system was implemented in one week, all during scheduled downtime.
The upgrade took the plant from obsolete to fully supported platforms. And the new HMI resolved the pop-up and alarm-management issues that had been frustrating workers.
The Rockwell Automation Library of Process Objects cut design, configuration and deployment time. In fact, Givens estimates the library helped cut programming configuration time by 40 percent. Even today, with the new system up and running, the library continues to provide efficiency savings.
“The library is helpful for maintenance and troubleshooting,” Givens said. “If we want to go in and change a description, we don’t have to go into an engineering workstation or programing software. We can do it right in the HMI using the faceplates. Or, if a valve won’t open, an operator can open a faceplate and then open an interlock icon to see what’s wrong. In the past, workers may have had to configure a screen to see the valve interlocks or sift through paper documents to troubleshoot the issue. Now, the answer is just a couple clicks away.”
Meanwhile, the batch software took the plant from very limited automation to full batch automation, including automated cleaning processes. This helped the plant achieve the level of quality control that its customer wanted. And after modifying the software to improve coordination between the different production units, the plant saw a significant boost in throughput.
“Instead of having a single-unit process, we now have a train of multiple units that coordinate with one another,” Givens said. “This was to increase production on a sold-out product.”
The plant is at work on expanding the project to other areas of the plant. This includes replacing the plant’s legacy I/O, putting in an Ethernet network and automating some of the portable tanks that still use manual processes. Givens expects this will only deliver more efficiencies and productivity on top of what the plant has already seen.
The results mentioned above are specific to DuPont’s use of Rockwell Automation products and services in conjunction with other products. Specific results may vary for other customers.
FactoryTalk and PlantPAx are trademarks of Rockwell Automation Inc.