By Paul Studebaker, Control editor in chief
With more than 60 years of experience, Teel Plastics specializes in custom extrusion of thermoplastic tubing
and profiles, producing annual sales of $50-60 million in a 150,000 sq. ft. facility in Baraboo, Wis. The ISO 9001-certified company makes geothermal pipe, solar film cores, coextruding products, healthcare tubing, specialty film cores, converting cores, filtration components, industrial tubing and more from materials including ABS, PEEK, polyethylene, polypropylene, polystyrene and nylon.
A new facility, opened in 2010, improved efficiency and saves energy by sending less than 1% waste to landfills, employing a variable-speed-drive compressed air system and frictionless chillers, recirculating rejected heat from production lines to heat to the building, and reducing wastewater to the city’s treatment plant more than 80%.
Most companies see plastic extrusion as a commodity. To expand its business, Teel specializes in medical, high-tech and other close-tolerance industries. “These require higher-quality parts manufactured to much tighter tolerances,” said Owen Gwynne, senior programmer, Teel Plastics in his presentation at Smart Industry 2017. At Teel, he said, spending money to improve quality “is an opportunity cost, as opposed to ROI.”
Extrusion is a semi-continuous process. Raw pellets are put into the extruder, where they are liquified with shear energy, pushed through a spider, pin and die into a vacuum tank/chiller, then into a puller/cutter. At Teel, product lengths range from 1/8 in. to quarter-mile-long reels.
Teel has dedicated lines of stations, and also constructs lines as needed to make specific products. The company sees IoT as part of laying a foundation for a smart factory and Industrie 4.0, Gwynne said. “We want to close the loop between quality control and manufacturing. We start with measuring the quality of the part, and determine what needs to be changed.”
Extrusion quality varies due to factors including material temperature, extruder pressure, puller speed, vacuum pressure, equipment wear, cooling, material variation and ambient humidity. To understand the effects, “We needed to measure more parameters in real time, with parts coming off at 60-70 meters per second,” Gwynne said. “Then, what can we change? Speed, yes, but not the humidity in the factory, which also matters.”
By collecting and analyzing data, engineers can build a control loop, where product quality measurements are fed into a computer system that determines what needs to be changed based on what is being produced, then changes the machine settings accordingly.
To specify a system, Teel breaks the loop down into steps and asks questions related to measurement, computing and final control actions:
- What should you measure? How do you measure? How do you collect measurements?
- How is an outcome impacted by a change? What needs to be reported? When do I call for help?
- What can be controlled? How do you control? What needs to be monitored?
Additional system requirements include the ability to design and build custom systems, and adaptable tools to accommodate a wide range of hardware. “Our customers always want something new,” Gwynne said, “and we need to adapt as new technologies become available.”
Creating IoT systems and building them out “is a huge process,” Gwynne said. Take a long-term view of success, but have payoffs at each milestone, he recommended. “We’re taking one step at a time, where we can provide value.”
Teel can automatically deliver setup information to its machines, and has a system to implement real-time changes. “Set-up was manual; settings were made using a checklist. Now the operator presses a button and all the adjustments are set by a computer,” Gwynne said. “Instead of operators walking the line, making adjustments on the fly, the setup parameters are programmed by Engineering, presented to the operator, accepted and implemented with the bush of a button.”
The set-up database lives in a custom system maintained by Engineering and listing all the equipment and settings for a specific part on a specific line. A web-based operator interface of custom software uses asp.net and Java script to pass settings to a Kepware IoT Gateway, which in turn passes information using a REST service to a wide range of plant-floor devices.
The user interface is browser-based. “All the interfaces look the same, across the plant and in our other plants,” Gwynne said. “Users can drill down and see thousands of parameters and specialized tooling. If there’s a reason, the operator can change a setting. Changes are automatically logged and the supervisor is flagged, and the machine can continue to run.”
Security is provided by a “pseudo air gap,” as the operator has to be at the machine and push a button to activate a change. “Operators love it – they don’t have to walk, or do paperwork,” Gwynne said.
The improved system has reduced set-up time by 30% and provides a consistent start point for all jobs. Gwynne sees it as the first step toward Industrie 4.0. “Smart Industry is a journey. Each step needs a payoff, and for our company, a highly flexible system is key,” he says. “As we moid toward more automated lines, we are reducing error, reducing set-up time, and collecting valuable information to improve production quality.
“Every day you can do a little more to make things run better.”