ZKW Group: Efficient Energy Technology for Premium Lighting Systems
The ZKW Group, headquartered in Wieselburg, Austria, is a leading provider of highly efficient premium lighting systems, electrical, and electronic modules for the automotive industry. In the construction of a new plant, special attention was paid to ensuring that building services equipment was optimally coordinated, thereby laying the foundation for the most efficient use of energy.
The company owes its outstanding market position to strengths in the areas of innovation, production expertise, flexibility, reliability, and service. A key objective in the development of lighting systems is to improve efficiency in terms of both energy yield and luminous intensity. However, improving efficiency is also a goal that is continuously pursued throughout the entire corporate organization. For years, the company has pursued an aggressive energy-saving policy in the area of energy supply. A current example of this is the new building for a cover plate factory with a logistics center constructed in the Haag industrial park in Wieselburg.
Regardless of lighting conditions, “seeing and being seen” is of vital importance in road traffic. For this reason, the performance of lighting systems in automotive engineering is constantly being put to the test and challenges the ingenuity of developers. In addition to the technology, however, the appearance of these systems also plays a key role. Headlight systems should therefore not only illuminate the darkness of the night but also give the vehicle an attractive and dynamic appearance. The manufacture of such complex and high-performance lighting systems and their components requires a correspondingly highly qualified and safe production environment. In the energy and media supply sector, the areas of refrigeration technology, heating, compressed air, and HVAC technology are therefore particularly critical. When designing and implementing the system technology, it is therefore essential to ensure the highest possible efficiency, consistency, and safety. “Together with the ONI experts, we developed a comprehensive media supply concept that was tailored to the specific requirements of our production conditions. Understandably, supply reliability was a top priority. As in our other plants, we also wanted to achieve the highest possible energy efficiency for the new plant in the Haag industrial park, because energy costs represent a significant expense for us. For this reason, we paid particular attention to optimally coordinating the building services equipment. In doing so, we laid the foundation for the best possible use of the energy employed,” says Günter Parb, the facility manager in charge, describing the objectives set at the start of project planning.
The key to efficiency is the system temperature
The new ZKW plant in Wieselburg-Haag manufactures lens covers for premium headlights. The lens covers themselves are produced using injection molding and then undergo a complex post-treatment process to achieve the properties required for road use. Hydraulically driven Engel injection molding machines with clamping forces ranging from 11,000 to 17,000 kilonewtons are used to manufacture the lenses. The machine tools and hydraulics are supplied by two separate cooling circuits with different temperatures.
This system separation was deliberately chosen because the goal was to create the conditions for utilizing the freely available waste heat for heating purposes rather than simply releasing it into the environment. “We know from implementing similar projects in other properties about the many advantages of this energy recovery. Specifically during the transitional and winter months, we not only double the use of the energy we consume but also avoid the energy costs associated with recooling via conventional recooling systems during these periods,” explains Peter Teufel, the person responsible for plant operations, describing the advantages of the system technology.
In order to make the waste heat from the machine cooling circuit available to as wide a range of users as possible, while also enabling the highest possible level of integration with other waste heat sources, the machines were equipped with so-called tropical coolers. These heat exchangers are capable of maintaining the temperature of the hydraulic oil at an optimal level with a cooling water temperature range of 42 to 37 degrees Celsius. The temperature in the cooling circuit return, which is seven Kelvin higher than in standard machines, offers the advantage—in addition to the diverse applications as a heating medium—that the size of the heat exchanger’s effective surface area can be significantly reduced. As a result, the investment costs for the heat recovery system are reduced. From machine cooling alone, approximately 450 kilowatts of waste heat are thus available for feed into the district heating network.
Compressed air generation, which was designed with appropriate oil coolers for heat recovery, provides an additional 210 kilowatts of waste heat, and cooling water generation for various company divisions with a supply temperature of 17 degrees Celsius provides up to 1,225 kilowatts for heating purposes.
Process-optimized mold temperature control
High-quality molded parts, such as the headlight lenses manufactured by ZKW, which must also have a stress-free, homogeneous material structure, require clearly defined and consistently maintained production conditions in the injection molding process. This is understandable when one considers that the best product innovations can only realize their full potential if the manufacturing process is managed in such a way that process stability is ensured for the entire batch with the shortest possible cycle times and continuous process monitoring to achieve near-zero-defect production. In injection molding, mold temperature control is therefore of crucial importance. Only intelligent temperature control management that individually controls and monitors each mold temperature control circuit ensures compliance with the unique thermal structure of the molded part being produced. Driven by the highest quality requirements, ZKW therefore uses dynamically operating Rhytemper® multi-circuit temperature control systems instead of conventional temperature control systems. By monitoring energy balances and adjusting parameters such as temperature difference and flow rate in each individual temperature control circuit, the thermal fingerprint of the molded part is kept virtually constant. The use of Rhytemper® technology also reduces the effort required for thermal run-in of the molds from the outset, as the thermal parameters of the molded part are immediately available after a mold change.
When a mold change occurs and preheating is complete, the optimal mold surface temperature is achieved in the shortest possible time upon production approval and monitored with every shot. The required cooling circuit supply unit, equipped with measurement and control elements, or the corresponding control unit, is mounted in a space-saving manner in the immediate vicinity of the mold base to keep tubing runs as short as possible. On the cooling water side, a separate circuit provides a temperature range of 17 to 20 degrees Celsius. Recooling is primarily achieved via a virtually free well water supply, which requires no additional primary energy beyond the electricity used to power the pumps. Only in cases where the well flow rate is insufficient or the power draw exceeds the well’s capacity due to the connection of other consumers are water-cooled, highly efficient chillers used to cover peak loads.
Low energy consumption for a healthy environment
“For the various business units, particularly in the production areas, the specific requirements for indoor air quality are clearly defined and must be maintained year-round through appropriate systems. The spectrum ranges from simple ventilation to state-of-the-art cleanroom technology. Typically, the operation of these HVAC systems incurs significant energy costs. “We therefore worked with the ONI experts to prioritize the highest possible energy efficiency right from the concept phase in order to minimize energy costs,” explains Peter Teufel regarding the objective set.
The ventilation supply for the injection molding area is provided by three central zone units, each with an air flow rate of 50,000 cubic meters per hour. The units are all equipped with a heat exchanger unit for heating and cooling operations.
Nearly 100 percent of the heating demand is met by waste heat from the injection molding machines, air compressors, or the chilled water production system. The cooling energy demand is met by the well water supply, and during peak periods, the highly efficient water-cooled chillers are used to generate cooling water. The areas equipped with zone units for the supply of conditioned air are organized in a similar manner to this system configuration.
“We must ensure 100% reliability in the supply of media such as heating and cooling water, compressed air, or conditioned room air through appropriate measures.
In this area, however, the requirement for supply security is closely followed by the demand for economically optimized energy efficiency. Even though energy price trends have currently taken a breather, we ensure that the highest possible energy efficiency is achieved in all the plants we construct and systems we deploy, while taking economic aspects into account. In this way, we aim to ensure that our energy costs are kept at a minimum level in the long term. “In the holistic plant concept implemented here at the site in collaboration with ONI, every possible opportunity for savings was utilized to achieve the set goal. This means we are well-equipped for the future at this location as well,” summarized project managers Günther Parb and Peter Teufel.
