Schneegans-Freudenberg Group: Reducing costs in silicone processing, reusing heat for greater efficiency
With the completion of its new facility, the Austrian plant of the Schneegans-Freudenberg Group—which has been recognized by machine manufacturer Engel for its innovative solutions—has once again optimized its energy systems with the help of Oni.
The core business of the Schneegans-Freudenberg Group’s Austrian facility is primarily multi-component injection molding and the production of tubes using water or gas injection technology for the automotive industry. And they are clearly doing this successfully: In 2014, the company was completely rebuilt near its old location—expanding its production area from approximately 6,000 to 10,000 square meters. Additionally, there is space available here for further expansion.
“In just twelve months, from the groundbreaking to the start of production, we established an injection molding operation optimized for energy efficiency, logistics, recycling, and waste management,” explains Managing Director Heinz Schulze.
Certified for energy-saving technology
A key aspect of the new concept: the systematic reduction of energy consumption across all areas—a process that had already begun at the old plant—was further advanced. In addition to Engel’s state-of-the-art, energy-efficient injection molding machines, Oni’s energy-saving technologies play a crucial role in the concept: for example, this made it possible to eliminate the need for separate heating systems in all parts of the building, including the administrative offices, right from the start.
Based on the experience gained from a largely in-house solution for heating and ventilating the production areas in the old plant, Oni was brought on board for the planning and implementation in the new building. “We had previously looked into a similar production facility that successfully integrated a comprehensive solution to reduce energy costs into its operations a few years ago,” explains Gerald Madlmayr, Head of Maintenance. Heinz Schulze adds: “We needed a partner who could not only supply and install the technology, but one with a high degree of flexibility. After all, due to the enormous time pressure, part of the planning had to take place during the construction phase—which was already underway—and then be implemented quickly.”
A circle is enough
Unlike a typical injection molding facility, Schneegans uses a single cooling circuit for both the molds and the machines—made possible by the low processing temperature of the silicones. The system operates at a supply temperature of 15 degrees Celsius, with a return temperature of 17 to 18 degrees Celsius. Currently, 35 injection molding machines with clamping forces ranging from 500 to 5,000 kilonewtons and a total cooling capacity of 250 kilowatts are integrated into the system. The heat generated heats all offices, workshops, and break rooms. The temperature of the production halls is regulated via an automatically controlled ventilation system.
The building’s floor slab serves as a large-scale heat storage system. Based on experience to date, this is sufficient to bridge even the two-week shutdown over Christmas and New Year’s. The emergency electric heating system installed as a backup has not yet been activated. To round out the picture, the heat from the compressors of the compressed air system is also utilized—even though they already operate relatively energy-efficiently thanks to electronic controls.
To anticipate an important result of the integrated cooling and heating technology, Heinz Schulze cites a hard figure: “Compared to the situation in the previous building, we can—with a year of experience now—estimate the energy cost savings at around 20 percent.” This figure also includes savings from improved building insulation, but the vast majority of the savings are achieved through the innovative heating and cooling technology.
Buildings and Energy-Saving Technology
The energy concept takes into account the specific nature of production: in addition to multi-component LSR injection molding, solid silicone is also processed. Accordingly, one hall with a volume of approximately 30,000 cubic meters can be fully cooled. The second hall, with a volume of 70,000 cubic meters, is used for multi-component injection molding and LSR processing.
Both halls are relatively high to optimize lighting and ventilation. In addition, machines and automation equipment can be easily set up. The “silicone hall” also serves as a “buffer” for the large hall when outdoor temperatures fluctuate rapidly.
All injection molding machines—including both the mold circuits and the hydraulic cooling systems—are connected to the supply and return lines installed in the halls. Depending on the outside temperature, the return flow is routed through heat exchangers for heating, through free-cooling units, and/or chillers to achieve the desired supply temperature on the one hand and to utilize the waste heat generated for heating purposes on the other.
The entire floor slab of the plant serves as a large heat storage system, ensuring a sufficient temperature level—which may be lower than during normal operation—even during extended operational interruptions, without the use of external energy. Integrated into the system is the control of ventilation in the production halls to achieve an optimal temperature level with comfortable ambient air.
The entire temperature control system for the machines is designed with some capacity for future expansions in a hall that may be added later and is also fully redundant.
In addition to the current 35 injection molding machines and production cells, there is 20 to 30 percent space reserved for additional machines. The same applies to the ventilation system, where piping designed to accommodate future expansion was already installed during the new construction. Despite the high complexity of the system, all the technology fits into a compact space. Easy-to-use controls allow employees to make adjustments to incorporate lessons learned from ongoing operations. “However, the settings and process values specified by Oni worked quite well,” explains Gerald Madlmayr. “So far, we’ve only adjusted a few parameters. We may undertake further optimization measures—that is, true fine-tuning—later this year, after gaining extensive experience.” This also applies to other energy consumers, such as lighting. After all, the Oni system is an important component of certification under the ISO 14001 environmental management standard, on the basis of which further minor optimizations are also being pursued.
Reach your goal faster
“Despite the enormous time pressure, the installation of the entire cooling and heating system kept pace with the construction progress—and went into operation without a hitch,” says Heinz Schulze, summarizing the project. We have taken care of the ongoing maintenance ourselves, as well as some minor adjustments to the control settings. Oni checks the system only once a year as part of a service contract. The employee training required for system operation took place during the acceptance process and was “not particularly time-consuming.”
According to Gerald Madlmayr, the fact that Schneegans-Freudenberg uses almost exclusively Engel injection molding machines is not solely due to their geographical proximity: “We primarily take advantage of the flexibility offered by the column-less technology.” The nature of the products often requires large-scale molds and sophisticated automation, but rather below-average clamping forces. With conventional machines, it would therefore often be necessary to switch to larger machines—which are less favorable in terms of investment and operating costs—in order to achieve sufficient installation space and accessibility for automation. Fewer tie bars mean greater flexibility in the selection and arrangement of components within the production cell, as well as in mold design. In 2015, the company received an award for a particularly innovative production cell built around an Engel tie-bar-less machine.
