Multiple use of heat for greater efficiency

The Austrian plant of the Schneegans-Freudenberg Group, which was honored by machine manufacturer Engel for its innovative solutions, has once again optimized energy technology with the help of Oni with the complete construction of the new company.

The core business of the Austrian site of the Schneegans-Freudenberg Group is to process multicomponent injection molding and pipes with water or gas injection technology for the automotive industry. In 2014, the company was completely rebuilt near the old site - and expanded from around 6,000 to 10,000 square meters of production space. In addition, expansion areas are available here for a further expansion stage. "In just twelve months, from the ground-breaking ceremony to the start of production, injection moulding production was optimised in terms of energy efficiency, logistics, recycling and waste management," explains Managing Director Heinz Schulze.


Reference for energy-saving technology tested

One important aspect of the new concept: the systematic reduction of energy consumption in all areas, which had already begun at the old plant, was further advanced. In addition to Engel's consistently modern, energy-efficient injection moulding machines, Oni's energy-saving technologies play a decisive role in the concept: for example, it was possible to dispense with separate heating in all parts of the building, including administration, from the outset.

Oni was brought on board to plan and implement the new building on the basis of its experience with a largely self-developed solution for heating and ventilation of the production areas in the old plant. "Previously, we had looked around a similar production facility that had successfully integrated a comprehensive energy cost reduction solution into the operation a few years ago," explains Gerald Madlmayr, Maintenance Manager. 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 ongoing construction phase and then be implemented quickly.


One circle is enough

In contrast to the typical injection moulding shop, a common cooling circuit for tools and machines is sufficient for snow goose - the low processing temperature of the silicones makes this possible. The processing temperature is 15 degrees Celsius, the return temperature is 17 to 18 degrees Celsius. Currently, 35 injection molding machines with clamping forces between 500 and 5000 kilonewtons and a total cooling capacity of 250 kilowatts are integrated into the system. The heat generated heats all offices, workshops and social rooms. The temperature of the production halls is regulated by an automatically controlled ventilation system. The floor slab of the building serves as a large heat accumulator. According to previous experience, this is enough to bridge even the two weeks of business interruption over Christmas and New Year. The emergency electric heating installed as a backup has not yet been activated. To round off the picture, the heat from the compressors of the compressed air system is also used: Although they are already comparatively energy-efficient thanks to an electronic control system.

To anticipate an important result of the integrated cooling and heating technology, Heinz Schulze quotes a hard figure: "Compared to the situation in the previous building, we can - with one year's experience now - estimate the energy cost savings at around 20 percent". This also includes parts from improved building insulation, but the savings are largely achieved with the help of innovative heating and cooling technology.


Buildings and energy-saving technology

The energy concept takes into account the special type of production: in addition to LSR multi-component injection moulding, solid silicone is also processed. Accordingly, a hall with a volume of around 30,000 cubic meters can be completely cooled. The second hall with 70,000 cubic meters is used for multi-component injection molding and LSR processing. Both halls are comparatively high to optimize exposure and ventilation. In addition, machines and automation equipment can be conveniently set up. The "silicone hall" also serves as a "buffer" for the large hall when outside temperatures change rapidly. All injection moulding machines - both the mould circuits and the hydraulic cooling system - are connected to the supply and return lines laid in the halls. Depending on the outside temperature, the return flow is routed via heat exchangers for heating, via free coolers and/or chillers in order to achieve the desired flow temperature on the one hand and to use the waste heat for heating purposes on the other. The entire base plate of the plant serves as a large heat accumulator, which ensures a sufficient temperature level without the use of external energy, even over longer interruptions in operation, which may be lowered compared to normal operation. Integrated into the system are the controls for ventilation and exhaust of the production halls in order to achieve an optimum temperature level with pleasant ambient air. The entire temperature control technology of the machines is designed with some reserves for future expansion in a hall that may still be to be built and is also fully redundant.

In addition to the current 35 injection moulding machines and production cells, there are 20 to 30 percent space reserves for further machines. The same applies to the ventilation, where the "incrementally" dimensioned piping was already laid during the new construction. Despite the high complexity of the system, the entire technology is accommodated in a compact room. Easy to operate controls allow the employees to intervene in order to be able to take into account empirical values from ongoing operation. "The settings and process values specified by Oni, however, fit quite well," explains Gerald Madlmayr. "So far, we have only adjusted a few parameters. Further optimization measures, i.e. real fine-tuning, will possibly be tackled in the course of the year after extensive experience". This also applies to other energy consumers such as lighting." After all, the Oni plant is an important component of certification in accordance with the ISO 14001 environmental management standard, on the basis of which further smaller optimisations are being sought.


Faster to your destination

"Despite the enormous time pressure, the installation of the entire cooling and heating technology was in line with the progress of the construction work - and started off flawlessly with the start of operation," Heinz Schulze sums up the project. We took over the ongoing maintenance ourselves, as well as a few minor adjustments to the control settings. The system is only checked once a year by Oni as part of a service contract. The staff training required to operate the system took place as part of the acceptance procedure and was "no longer time-consuming".

According to Gerald Madlmayr, the fact that Schneegans-Freudenberg almost exclusively uses injection molding machines from Engel is not only due to the close proximity: "We primarily use the degrees of freedom of tie-bar-less technology. The nature of the products often requires voluminous moulds and sophisticated automation, but rather below-average clamping forces. With conventional machines, it is therefore often necessary to switch to larger machines - which are less favourable in terms of investment and operating costs - in order to achieve sufficient installation space and accessibility for automation. Less tiebar means more flexibility in the selection and arrangement of components in the production cell and in tool design. In 2015, the company received an award for a particularly innovative production cell around an Engel tie-bar-less machine.