Backhaus Plastics Technology: Curbing the Energy Consumption of Injection Molding Machines
The name Kunststofftechnik Backhaus has an excellent reputation in the automotive industry and other sectors that place particular emphasis on quality, innovation, and on-time delivery. Following a management buyout, the new owner, Manfred Gante, together with a core team of 130 employees, succeeded in steering the company—which had been spun off from a corporate group—back onto a stable course after twelve months of hard work. In doing so, the company’s CEO has consistently focused on improving energy and process technology to regain the competitiveness that is absolutely essential.
“From my previous role as plant manager, I knew which areas had room for improvement. We had to succeed in realizing this potential as quickly as possible to ensure the company’s continued existence and, with it, the preservation of many jobs. Since I have known Wolfgang Oehm, the managing partner of ONI-Wärmetrafo GmbH in Lindlar, very well for years and value his expertise in plastics processing, it was clear to me that his team’s commitment to energy and process optimization would be crucial for the relaunch. We had to set a high goal and expected a positive outcome!”
says Manfred Gante, describing his motivations for a systematic realignment of the company in terms of energy efficiency and process optimization.
The electricity consumption of injection molding machines accounts for the lion’s share of Backhaus’s electricity bill and a significant portion of its total costs. The sharp rise in energy prices—which continue to climb—is therefore placing an increasing burden on the company. For this reason, the company is seeking ways to reduce the machines’ electricity consumption effectively and sustainably. The “EtaControl®” technology presented by ONI should prove to be the ideal solution. “Initially, we were quite skeptical about this technical solution. While we want to reduce our electricity consumption with this technology, we must under no circumstances allow it to have negative effects on our manufacturing process. After receiving a corresponding commitment from ONI and seeing the savings achieved at other processors, we were practically compelled to at least conduct a test with the ‘EtaControl®’ technology,” Gante summarizes his concerns at the time. The core of this technology is controlled oil flow management that automatically and on-demand adapts to the machine’s energy requirements during the cycle and to the specific molded part. In advance, power measurements are taken on the machine during the ongoing production process and a power profile is created. Power adjustment in actual operation is then carried out via an intelligent frequency control system newly developed by ONI, which is integrated into the existing control system of the injection molding machine.
The control system does not interfere with the existing machine control system but operates independently. Process information such as signals from potential-free contacts regarding the cycle sequence, currents from the proportional valves, and analog pump signals from the machine are used as control parameters.
A key advantage of this technology, in addition to significant energy savings, is that the performance of the injection molding machine is not restricted—it is maintained at 100 percent! A key switch allows the “Eta-Control®” power adjustment function to be easily turned on or off while retaining the machine parameters and cycle times.
A pilot machine with a clamping force of 660 MP and a drive power of 75 kilowatts was selected for the test run. According to power measurements taken before the retrofit, approximately 41 kilowatts of that power were actually required for the manufacturing process. After the retrofit and installation of “EtaControl®” technology, only approximately 23 kilowatts were required for the same manufacturing process, while maintaining all machine parameters. The resulting 18-kilowatt reduction in power consumption was an extremely impressive result.
Taking into account only 4,800 annual production hours, this results in an annual electricity savings of 86,400 kilowatt-hours. In addition, the load on the machine cooling system and the transformer station is reduced, peak consumption is lowered, and connection capacities are freed up for production expansions. Thus, a single measure to reduce energy consumption has several knock-on effects that positively impact the overall energy balance.
“Although we had certain expectations based on the project presentation by the ONI experts, the result of the machine optimization at the pilot plant was stunning to us. Following this outstanding result, we commissioned the retrofitting of the machines proposed by ONI and were thus able to reduce the electricity consumption of these machines by approximately 40 percent. “It is particularly gratifying that the costs for the machine optimization will pay for themselves in about 1.3 years through the savings achieved across all areas,” says Manfred Gante, summarizing the use of “EtaControl®” technology.
In injection molding, quality, process stability, and unit costs are largely determined by mold temperature control. While this insight is not new, the results achievable through product-oriented temperature control are often overlooked due to a lack of comparability. Manfred Gante, however, quickly recognized the advantages of the dynamically operating “Rhytemper®” mold temperature control system.
Backhaus manufactures high-quality plastic parts for a wide variety of industrial sectors. As is the case everywhere, product quality and unit costs are decisive factors when it comes to customer loyalty and competitiveness. For some products, it had become apparent that achieving the required product quality was difficult with conventional temperature control technology, and that the necessary short cycle times were simply impossible to achieve.
The consequence would have been a loss of significant order volume or operating at a deep loss, both of which would have caused major problems for the company. This issue had to be addressed efficiently, and the company turned to the dynamically operating “Rhytemper®” temperature control system from ONI.
To obtain an objective comparison between conventional temperature control technology and dynamic systems, comparable conditions had to be created. Thus, operating and production processes were optimized in advance, and all possibilities of conventional temperature control technology were exhausted. Only after this optimization was implemented and results regarding quality, process stability, and cycle time were available was production continued using the “Rhytemper®” technology. The results in this area were very convincing. Cycle times were reduced by between 10 and 22 percent, energy consumption was significantly reduced, and the scrap rate was noticeably lowered. As an added benefit, it was observed after the “Rhytemper®” installation that the load on the mold cooling circuit decreased noticeably.
“We know from experience that modern machine technology, combined with innovative tool design and high-quality tools, requires a tool temperature control system tailored to the specific system. Only when all components involved in the core process are operating optimally can we ensure the consistent production of top-quality products with the lowest possible energy consumption. “For this reason, we have consistently implemented ‘Rhytemper®’ technology, maximized its benefits, improved our product quality to a significant degree, and, above all, regained control of our unit costs,” explains Gante, sharing his experience with modern ONI temperature control systems.
In the past, the cooling water for the injection molding tools—maintained at a constant supply temperature of 12 degrees Celsius—was generated year-round using chillers. However, chillers are energy-intensive and result in high electricity consumption and correspondingly high electricity bills. At Backhaus, the ONI concept calls for cooling energy to be supplied by chillers only during the warm summer months and the transitional period. Chillers are not used for approximately 65 percent of production hours. During the transitional and winter periods, a so-called “winter relief” system handles the cooling energy supply for the tooling area, which has a capacity of more than 500 kilowatts. With this technology, existing free coolers replace the chillers entirely or partially depending on the outside air temperature, reducing energy consumption to approximately two to three percent of the previous consumption level.
Instead of natural gas or heating oil, Backhaus uses free waste heat from the oil cooling system of the injection molding machines for its heating supply. The temperature of 35 degrees Celsius in the cooling circuit return is ideal for heating rooms. In Backhaus’s case, this amounts to approximately 1,000 kilowatts of waste heat output. As long as waste heat from the machines is available, heating is provided free of charge.
Heating is provided by a conventional heating system for just a few hours a year, during which the machinery must be shut down for maintenance. “With this heating concept from ONI, we have been able to reduce our heating costs by approximately 90 percent. “In light of further expected energy price increases, this technology cannot be praised highly enough,” says Manfred Gante, taking stock of the situation in this area.
“Given the situation we were in, we were very fortunate to have a partner like ONI by our side. They didn’t just want to sell us something. The team led by Wolfgang Oehm provided us with helpful support and advice in a wide variety of areas, even when there was nothing to sell…that’s what we mean by partnership-based collaboration. With the energy concept implemented by ONI, we have succeeded in getting our energy costs back under control and significantly improving our competitiveness. The fact that we are also making a significant contribution to reducing our environmental impact is a welcome and positive side effect that benefits us all,” says Manfred Gante, summarizing his overall experience with the project implementation alongside ONI.
