The ecological and economic business climate for energy-intensive industries is getting tougher: Rising energy prices, gradually increasing costs for CO2-emissions, and clearly formulated requirements for sustainable production sites by end customers are presenting foundries with challenges. Europe wants to become the first climate-neutral continent in the world. With the help of the European Green Deal, this goal is to be achieved by 2050. An important milestone in this respect is already due in 2030: the EU recently agreed to reduce greenhouse gas emissions by at least 55% compared with 1990 levels. The introduction of a CO2 tax will further increase the attention to key figures such as the carbonfootprint, because since 2021 25 euros per tonne of CO2 are due, and in 2025 it will be already 55 euros per tonne of CO2. It is therefore not surprising that forward-looking foundries are taking a close look at their carbon footprints. For DGS Druckguss Systeme, this challenge is a perfect opportunity.
The innovative Swiss company quickly recognized that rising energy costs and future CO2 taxes could best be met by sustainably reducing energy consumption in all of the group’s plants. After all, foundries are known to require a great deal of energy. That is why the Swiss have taken a close look at their internal value chain. In addition to the melting and casting process, exhaust air technology in particular proved to be an area with high energy consumption: If high quality standards in terms of air quality are to be maintained, large air exchange rates and powerful filter systems are required.
At DGS, the procurement of exhaust air and filter technology therefore became a decision of strategic importance, as it has a high CO2 avoidance potential and has become an integral part of DGS’s extensive climate protection activities. Today, a certified environmental management system bundles the activities of all sites and is continuously developed further in close cooperation with customers, suppliers and authorities. The responsible environmental manager in St. Gallen carries forward the step-by-step adaption of the realized high sustainability standards in Switzerland to further DGS sites in the Czech Republic and China.
DGS operates internationally with over 1,240 employees in St. Gallen and three additional sites in the Czech Republic and China. The foundry, whose customers come with over 95% primarily from the automotive industry, was founded in 1925 as the ‘test laboratory’ of the die casting department of Bühler AG and is today a leading supplier of complex and high-quality die cast components made of aluminium and magnesium.
Regarding the procurement of building exhaust air technology DGS Druckguss Systeme AG had long ago decided in favour of filter systems from KMA Umwelttechnik and had numerous filter systems in operation at its headquarters in St. Gallen as well as in China. This is because the Ultravent filter from KMA is recognized in the industry as the benchmark in terms of energy efficiency for a long time.
With the new Ultravent III series, which KMA launched on the market in spring, the environmental engineers from Königswinter in Germany open up even more possibilities for their customers in terms of energy savings: the exhaust air filtration system features modified, more streamlined housings and, in combination with modified control technology and high-efficiency fans, achieves a reduction in energy consumption of more than 40% compared with their predecessor. Compared to conventional fabric filter systems, energy consumption is even reduced by more than 70 to 80%.
Energy-efficient state-of-the-art foundry
Due to increasing global demand for structural components, DGS is building production expansions in all three regions (Switzerland, Czech Republic, China). The new production hall built in St. Gallen is considered a model factory in terms of efficiency and environmental compatibility for the production plants in the Czech Republic and China. The installation of energy-efficient exhaust air filtration systems is out of the question here: The 4,400- tonne casting cell recently commissioned in Sankt Gallen is currently the largest die casting machine installed in Switzerland. It was equipped with a KMA Ultravent III exhaust air filtration system.
DGS uses minimum quantity spray technology for the thin-walled structural components. Lightweight die cast components are particularly suitable for this process because they store little heat energy and the mould surfaces become less hot than with other processes. Thanks to specially designed surfaces and cooling circuits, the moulds require significantly less cooling water in the spraying process and are therefore more resource-efficient than conventional processes – another plus for environmental protection.
Smoke extraction directly at the emission source saves energy
Energy-efficient exhaust air treatment starts with smoke extraction. The most energy-saving method is an extraction hood directly above the emission source. In this way, the extraction hood captures smoke and aerosol mist directly at the point of origin and prevents them from spreading and polluting the entire hall air. This is because the lower the volume of exhaust air to be cleaned, the lower the associated energy costs. In addition, the control of the filter system allows for flexible adjustment of the extracted air volume to the current air load in each phase of the casting cycle. If, on the other hand, smoke collection would take place below the hall ceiling, the entire hall air would have to be exchanged and filtered 10 to 15 times per hour.
Automatic opening mechanisms on the extraction hood ensure unrestricted accessibility of the moulds and die casting machines. The new casting machines in St. Gallen were equipped with one-piece hoods which can be moved completely, thus making the machines fully accessible during mould changes, from the outermost part of the moving plate to above the injection side.
Electrostatic precipitators reduce resource consumption
Smoke extraction is followed by exhaust air treatment. The filter system of the new 4,400-tonne large machine has a flexible exhaust air capacity and is designed for a maximum exhaust air volume of 25,000 m3 per hour. With the Ultravent filter series, KMA offers an energetically optimized system for almost any exhaust air situation in the die casting industry. A demister serves as a pre-filter and enables a high separation efficiency of coarse particles. The subsequent electrostatic precipitator represents the heart of the filter system. Electrostatic filter cells permit the high-grade separation of smoke, dust and the finest mist. Even the ‘blue haze’, produced when using separating oils, with particle sizes in the submicron range is separated.
The DGS staff is also pleased about the high air quality in the new foundry. „Our workforce in the production hall is very happy about the remarkable clean air condition thanks to the air filter systems and confirms that their work is more enjoyable under these circumstances. This is even more important considering the fact that our trainees and hence our young talent technologists will complete their professional training on these machines,” says Andreas Müller, CEO of DGS Druckguss Systeme AG.
Global environmental protection at DGS
In Guandong, where the Chinese DGS plant is located, the first casting machines have also already been equipped with KMA systems. Thanks to integrated remote maintenance, the access to the operation-relevant data of the filter systems is possible at any time. This allows monitoring and service to be carried out ‘remotely’ to a large extent. All exhaust air purification systems have an integrated filter cleaning system (CIP), which cleans the module elements fully automatically on a regular basis and in this way ensures the long-term use of the filter cells. The cleaning times can be programmed by the customer as required in accordance with his production planning. The maintenance effort is thus reduced to a minimum. By using adaptive environmental technology, DGS ensures, among other things, that the defined measures of its environmental standard can be ensured not only at the headquarters in Switzerland, but also at the distant production sites.
Climate-neutral production from 2039
To achieve the EU’s climate targets, the entire aluminium die casting industry must rethink. The example of DGS shows how active environmental management can set the strategic course of a company and make a major contribution to global climate protection. Müller has already paved the way to sustainable success and has equipped his company well for the future. “DGS is highly committed to sustainable production and invests in energy-optimized solutions,” he says. “Examples include exhaust air purification, a 670 kWp photovoltaic system, the purchase of electricity from hydropower, the connection to a district heating network in which waste heat from the processes is decoupled and will be used in the future to heat a shopping centre and a soccer stadium, and the conversion to lower-CO2 inert gases. Within the last six years, DGS has been able to reduce its CO2 footprint by more than 90%! We have committed ourselves to our main customers to produce CO2-neutral from 2039 onwards.”