Electricity and Control November 2022

SENSORS + SWITCHES

Fine tuning temperature sensors to handle new plastic packaging Marine plastic waste is a global problem. About half of the plastics that enter the oceans are packaging materials such as containers and wrapping.To reduce the environmental impact, manufacturers around the world are looking for ways to switch from plastic packaging to eco-friendly alternatives. One of the challenges is that new materials require finer temperature control in the process of heat-sealing packages.With a view to resolving the bigger issue of marine plastic waste, a team at OMRON set about developing a temperature controller that would overcome the packaging defects arising with the use of eco-friendly materials.

P lastic bottles and containers washed up on the beach, plastic bags drifting in the ocean... The bur den of marine plastic waste has become a serious problem worldwide. It is reported that over eight million tons of plastic waste enter the oceans every year. If no action is taken, some sources estimate that by 2025, the cumulative amount of plastics dumped in the oceans will be about one billion tons, outweighing all the fish in the sea. Plastic waste in the oceans has a multitude of harmful effects on the ma rine environment, the marine ecosystem and marine organ isms. It pollutes the seas and in turn becomes a threat to human life and the planet as a whole. Efforts are under way to reduce the use of plastics. In the industrial sector, many companies are switching from plas tic to paper materials, or to thinner plastics, or biodegrad able plastics (that is, plastics that dissolve in the natural environment) for containers and packaging. However, the thermal reactivity of new packaging mate rials differs from that of conventional plastics. Usually, when plastic is used to package products, heat is applied to seal the packages. Attempts to switch conventional packaging machines to using eco-friendly materials have presented a number of problems, which have deterred some compa nies from making the change. Paper packaging materials

present a problem in that they do not conduct heat well, and thin-walled plastics and biodegradable plastics have such low thermal tolerance that they do not glue well, shrink with heat causing wrinkling, or get scorched or melt. This results in an unacceptable level of defective packages. This impasse came to the attention of Miho Nishide, who was developing temperature controllers with the product planning team of OMRON’s Components Division, Product Business Division HQ. OMRON has a history of more than 50 years of developing and manufacturing temperature controllers for a wide range of industries and is among the largest players in the global market. With a sincere wish to address the social and environmental issues caused by marine plastic waste, she embarked on the develop ment of a new family of temperature controllers, leverag ing OMRON’s technology to expedite the introduction of eco-friendly packaging materials. With common automatic packaging machines, once a package is filled with product it is sealed at the mouth by metal bars heated to a high temperature (sealing bars). It is important to keep the correct temperature on the surfac es of sealing bars. If the temperature is even marginally lower or higher, it will cause packaging defects. “Our goal was to reduce the temperature fluctuation on the sealing surfaces during the packaging process to one-tenth of that on conventional machines,” Nishide recalls. She soon re alised that this was an unexpectedly daunting challenge, even with OMRON’s long history of experience in leading temperature control technology. How can a packaging defect occur when the tempera ture is set correctly? At first, members of the team did not fully understand the mechanism of the controller. Questions arose: “Can we really solve this with OMRON’s technology? Given the variety of materials, thickness, and the number of layers, there would be tens of thousands of types of pack aging materials, and it’s simply impossible to accommo date all of them.” The team became uneasy but everyone chose to keep going. The impetus came from the overriding goal. “We A temperature controller to eliminate packaging defects

Marine plastic waste is a worldwide problem threatening marine life and ecosystems.

18 Electricity + Control NOVEMBER 2022