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The perfect safety net - WOCO Eisenacher Kunststofftechnik relies on safe Reisner refrigeration

Production downtime is a worst-case scenario feared by plastics processing companies, especially if automotive customers with high demands are waiting for their deliveries. Consequently, operational safety belongs to the most important issues when it comes to setting up a new plastics production plant. To a very large extent, this also applies to the cooling technology. WOCO Eisenacher Kunststofftechnik GmbH, a plastics processor located in the east of Germany, chose to play it safe when they established their new location. They chose a cooling system created and manufactured by Reisner Cooling Solutions GmbH which provides substantial redundancy while staying economical during everyday operation.

Time for new equipment – time to set new priorities. For the Eisenach-based plastics processor, this process started when they decided to set up a new location. Their plan was to step by step rent several halls belonging to a complex of buildings and equip them with injection moulding machines. The new compound is supposed to produce a broad range of automotive parts from mudguard coverings to e-bike components. These plans already set clear priorities concerning the cooling required. As the production will be extended during the foreseeable future, the cooling performance will have to adapt to these changes. Besides, maximum operational safety for the highly demanding production line must be guaranteed at all times.

Long-term project based on valuable experience
Martin Stützer, the customer’s commercial manager, works for the company since 2007 and has gained in-depth knowledge about production and cooling supply. “We have been using Reisner systems at our existing premises for a long time, with many additions and extensions made over the decades. Reisner has also provided maintenance and support and they know our situation well which is why we requested a quotation from them when planning our new location”, he reports. Currently, the new production in Eisenach operates four injection moulding machines with a clamping force of 1.000 tons each. The development is expected to be completed by 2022. At this final stage the equipment will comprise eight large 1.000-ton machines and several smaller ones with 150-200 tons each.

Accordingly, cooling technology must be well balanced to provide future-safe performance without being over dimensioned. WOCO Eisenacher Kunststofftechnik and Reisner have developed a suitable concept together during the quotation phase. Reisner have adapted their design several times, intensively advising their customers on every single step. This has been a most valuable support for Stützer and the team: “Reisner have proven a special understanding for our demands and developed creative ideas. Our contact person, sales director Günter Sareyko, exactly prognosed the consequences each single decision would entail. We always received all necessary facts very quickly. This way, we could make all our decisions on a basis of sustainable information.”

Priority: operational safety
From the very beginning, the team focused on operational safety. As the new location is supposed to supply the automotive industry, availability was a top priority. The risk of a total interruption had to be reduced to zero. In case of failure of one system element, the others should be able to hold up at least 60% of the production single-handedly. The whole concept was based on this requirement. When designing the cooling machine for tool cooling, Reisner opted for a double system with two high-quality compressors of 96 kW cooling performance each. Both compressors were integrated into their own refrigerant circuits including evaporator and condenser. A dry cooler was added for winter relief.

The supply network inside the building was planned accordingly. “The pipework inside the hall was very complex”, Stützer says, “our main target was to enable the cooling units to support the largest part of the production independently. Therefore, we needed more pipes, more valves, and more shut-off valves as we would have needed with a simpler solution. But Reisner has planned the piping system meticulously and made perfect use of the space at our disposal. They managed to meet all our requirements.” The cooling technology itself brings another advantage concerning space utilization, as it is fully integrated into a 12 m long container. It serves as an additional machine room and puts a previously unexploited space behind one of the buildings to a perfect use.

Reliability at a reasonable price
To make the system not only safe but also efficient in operation, Reisner has included all available technical features for energy saving to the system concept. As a refrigerant, they use R513A. With its superior thermodynamic qualities, it guarantees a smooth operation of both cooling machines at a low GWP. “GWP”, short for Global Warming Potential, indicates how much a substance enhances global warming. The higher the value, the more damage is inflicted on our climate. There are remarkable differences between refrigerants. R410A for example, which is still widely in use today, has a GWP of 2088, while that of R513A is only 631. With decreasing outside temperatures, the cooling machines delegate more and more of their load to the self-draining dry cooler which is used for winter relief and completely takes over below a defined outside temperature. This saves up to 100% of the compressor’s energy consumption. The condenser is equipped with EC fans using motors with integrated control electronics. They adjust their fan speed continuously to the actual requirements, thus consuming less energy than common AC fans and emitting less noise.

On the hydraulics side, the Reisner system keeps operational costs low in the long run, too. Reisner CEO Thomas Imenkämper and his team always choose their cooling methods according to the tasks at hand in the customer’s production. “The hydraulics cooling for WOCO Eisenacher Kunststofftechnik allowed us to operate with a comparatively high supply temperature. Therefore, we have covered this field using only free cooling. One of the dry coolers is fully dedicated to hydraulics, and the dry cooler mainly used for winter relief on the tool side can provide support, if necessary. We have resigned from including an energy-consuming compressor chiller.” Even at the highest outside temperatures during summertime, the required safety is always maintained. Reisner has installed a plate heat exchanger on the system’s water inlet. Only if required, it is flooded with additional cold water – a measurement as water-saving as security-enhancing. The thermal energy taken from the production lines does not go to waste: Reisner make it usable for heating the production halls by installing a waste heat recovery system. This way, they substantially lower the heating energy demand and induce another drastic reduction of operating costs.

Cooling with that special extra – and an expert project realization
Inside the sophisticated water circuit, efficient circulation pumps transport the water through a high-quality pipe system consisting of corrosion-free material. Two separate tanks are installed, one for tool cooling and one for hydraulics cooling. These tanks were accurately fit to the spatial situation inside the container and manufactured at the Reisner premises. Built from opaque, robust PP plates, they are stabilized by plastics-coated steel frames. As clean cooling water is an influential factor to operational safety, the cooling system is equipped with a full range of water treatment features. Each tank contains a full stream back flow filter system with stainless steel filter baskets and mesh inserts. These filters remove nearly all solids without pressure or backwater. The inserts can be cleaned without interrupting operation. Additionally, dosing pumps treat the system at regular intervals strictly according to the actual requirements against corrosion, microbiological contamination and algae. This means a real relief to the staff in Eisenach – they do not need to keep the intervals in mind, and they do not have to handle the chemicals themselves.

Despite all the sumptuous details added to the system, during the project phase Reisner had to maintain a tight schedule. Only 14 weeks were budgeted from order placement to commissioning. Stützer recalls: “Reisner have agreed to our targets, and we trusted them to implement the project completely as planned. Now we have commissioned the system on time.” After commissioning, Reisner will keep up the regular maintenance, says Stützer: “In our production, the situation changes from day to day. New machinery, master sample approvals, other developments – our cooling technology must keep up with all that. By providing the intensive care guaranteed by the maintenance contract, Reisner is always up to date about our production’s needs. This way, we can react fast, expand our systems as required and above all absolutely rely on our cooling technology, now and in the future.”

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