Plastics and Electrical Engineering, Inc.: Top Quality at Low Energy Costs
Plastics and Electrical Engineering GmbH uses cooling system technology from ONI (ONI-Wärmetrafo GmbH) at its production site in Mönchweiler.
ONI cooling systems in practical use: Kunststoff- und Elektrotechnik GmbH in Mönchweiler is one of the industry’s leading names when it comes to expertise, innovation, and quality in the development and production of plastic products. The company offers a wide range of services, which today extends from product development, toolmaking, single- and multi-component injection molding—including hybrid part production—to the assembly of subassemblies and the finishing of components with a focus on appearance, feel, and function.
For over 40 years, the company has served as a development partner to renowned clients and has been manufacturing custom thermoplastic and thermoset molded parts in the Schwarzwald-Baar region to meet the highest standards across a wide range of industries. For just as long, it has been part of the Furtwangen-based Siedle Group, which has made a name for itself with innovative building communication systems.
Horst Siedle, who shaped the company of the same name for nearly four decades as its owner and managing director, recognized early on the potential of plastic as a material. With foresight, he harnessed the material’s advantages for his own products and many others. To bring his ideas and visions to life, he needed the necessary expertise and machinery. In his search for a suitable company, he found what he was looking for at Kunststoff- und Elektrotechnik GmbH in Mönchweiler.
Today, the company operates as a valued partner for clients in the automotive, electrical engineering, medical technology, sensor technology, and consumer goods sectors. From concept to production-ready: products are optimized to meet specific customer requirements and manufactured to the highest quality standards using advanced tooling and state-of-the-art machinery.
The company’s machinery currently includes a total of 40 injection molding machines with clamping forces ranging from 250 to 5,000 kN. KE-Technik takes particular pride in its “specialized expertise, especially in high-temperature thermoplastics and thermosets,” as Harald Helms, Managing Director of Kunststoff- und Elektrotechnik GmbH, explains.
Quality standards are high—regardless of the business division. In the same breath, Helms emphasizes the commitment to sustainability and active environmental protection that the management has imposed on itself. “Sustainable practices and the associated responsibility, both for our environment and for our employees, are firmly anchored in KE-Technik’s corporate philosophy. For us, the efficient use of energy is a key factor in this context.”
The bar was set correspondingly high for the new building completed in 2014 to expand production, warehousing, and administrative facilities. A comprehensive set of requirements was formulated for this project. According to these requirements, all energy-related systems and components were to be designed with the highest possible efficiency to ensure sustainably low energy consumption and, consequently, to address environmental protection considerations in the best possible way. To implement the systems for cooling energy supply, waste heat recovery, and heating, as well as controlled hall ventilation, the project managers brought on board ONI-Wärmetrafo GmbH from Lindlar.
There was a simple reason for this, as Roland Metzler, Head of Technology at Kunststoff- und Elektrotechnik GmbH, reveals: “ONI’s overall concept was simply sound and convincing, and in hindsight, our positive experiences have confirmed that we made the right decision.”
“ONI has demonstrated in an exemplary manner what it means to professionally implement such a complex system and ensure the smooth and efficient operation of the entire facility, as promised. In doing so, the ONI sales manager in charge has also fulfilled the commitment he made when the order was placed.”
In line with KE-Technik’s own quality standards, the technical requirements for ONI were also very high. Additionally, there was a requirement to integrate existing buildings into the supply concept and ensure that production continues uninterrupted.
A two-circuit cooling system was selected. Through separate piping, this system supplies the tool and machine cooling circuits with the required temperatures. To cool the injection molds, the water is cooled to a temperature of 18 °C. An energy-optimized, water-cooled ONI chiller is used to recool the tool circuit. Specifically, the tool circuit is supplied with a total capacity of 187 kW. To provide the cooling water required for tool-side cooling, chillers are typically used year-round.
With a winter load reduction system from ONI, the use of the chiller at KE-Technik is significantly reduced. During the colder months, ambient air is used for cooling. Two open-air cooling coils are installed on the factory roof for this purpose. If the outside temperature falls below the temperature of the return water in the tool circuit, recooling takes place via the glycol-free open-air coolers.
“We cover just about everything with our outdoor fans, which are, of course, also much more energy-efficient,” says Metzler. “Even before the chiller kicks in at certain outdoor temperatures, we have the option of spraying the fans with a fine mist of water.” This helps lower the temperatures by an additional 2 to 3 °C. “So the chiller only runs when we’re really operating at full capacity, in the height of summer,” Metzler emphasizes. The machine cooling circuit is supplied with a cooling capacity of 341 kW, provided by glycol-free open-loop coolers. To maximize the utilization of waste heat from the cooling water, the cooling water temperature is maintained at 34 °C.
Operational safety is the top priority. It was therefore crucial to KE-Technik that the entire system be designed to be fail-safe with the necessary redundancy. All pumps are therefore duplicated. “This gives us the highest possible level of safety, which is ultimately what we depend on,” emphasizes Metzler.
Many industrial companies share the desire to reuse energy multiple times and thereby reduce energy costs. ONI’s energy concept is designed to do exactly that. The majority of the waste heat from the machine cycle is used to heat various sections of the plant.
During the transitional and winter months, this allows office spaces in the newer part of the plant, as well as the warehouse, to be heated via underfloor heating. For Metzler, this is a factor that not only has a positive impact on costs but also influences production quality: “Using the waste heat, we are able to maintain our stored plastic raw materials at a constant temperature of 18 to a maximum of 19 degrees.”
With the Oni heat recovery system, energy can thus not only be utilized twice, but the effort required to recool the cooling water circuit is also eliminated during the period of waste heat utilization.
One factor that significantly influences process reliability as well as production efficiency and energy consumption is the quality of the cooling water. “Water quality was an issue for us at first. The biological contamination of the cooling water led to increased effort in tool management, cycle times got out of hand, and the costs for purchasing and handling chemical additives rose significantly,” recalls Metzler.
The Oni experts had an efficient solution for this problem. The Oni-Aquaclean system technology, a combination of filtration stages down to 0.1 µm in conjunction with intrinsically safe ozonation, delivered an impressive improvement in water quality within a short time. This technology massively suppresses biological growth in the form of algae and bacteria in the cooling water and keeps it continuously in check. Contaminants down to the finest particles are filtered out and thus no longer deposit on the wall surfaces of the cooling water channels in the mold. As a result, the conditions for heat exchange in the mold—and thus the process conditions—are significantly improved.
“Since the ONI Aquaclean system has been in operation, we’ve seen excellent cooling water quality,” Metzler emphasizes. “There are no longer any solids or turbidity in the water; everything is filtered out, and we no longer need to use biocides.”
The collaboration with ONI demonstrates that through consistent planning and implementation of modern and, above all, energy-efficient technology, energy and operating costs can be reduced to a minimum while still meeting the required high quality standards within the manufacturing process. The implementation of an economically and ecologically balanced energy concept at the Mönchweiler site has been a success for all involved and has ultimately delivered the desired results. Kunststoff- und Elektrotechnik GmbH is convinced that having ONI as the right partner by their side is the right choice—even for future projects.
