The name Kunststofftechnik Backhaus has a very good reputation in the automotive industry and other industries that attach particular importance to quality, innovation and delivery reliability. After a management buy-out, the new owner, Manfred Gante, together with a 130-member core team, managed to steer the company, which was separated from a group structure, back into safe waters after twelve months of hard work. The head of the company has consistently focused on the improvement of energy and process technology in order to regain the compellingly necessary competitiveness.

"From my previous position as plant manager, I knew in which areas there was potential for optimization. We had to succeed in raising this potential in the shortest possible time in order to secure the continued existence of the company and thus many jobs. Since I have known the managing partner of ONI-Wärmetrafo GmbH from Lindlar, Wolfgang Oehm, very well for years and appreciate his knowledge about plastics processing, the commitment of his team with regard to energy and process optimization at the restart was a clear thing for me. We had to set ourselves a high goal and expected a positive result," is how Manfred Gante describes his reasons for consistently reorienting the company in terms of energy efficiency and process optimization.

The electricity consumption of injection moulding machines accounts for the lion's share of the electricity bill and a significant share of the total costs at Backhaus. The sharp rise and further rise in energy prices are therefore placing an increasing burden on the company. For this reason, the company is looking for ways to reduce the power consumption of its machines effectively and sustainably. The "EtaControl®" technology presented by ONI proved to be the ideal solution. "We were quite sceptical about this technical solution beforehand. Although we want to use this technology to reduce our power consumption, we have to avoid any negative effects on our production process at all costs. After ONI had promised to do so and the savings achieved by other processors had been presented, we were literally forced to test the 'EtaControl®' technology at least once," says Gante, summing up his concerns at the time. The core of this technology is a controlled oil flow management system that automatically adapts to the energy requirements of the machine in the cycle sequence and the respective moulded part. Prior to this, performance measurements are carried out on the machine during the ongoing production process and a performance profile is created. An intelligent frequency control newly developed by ONI, which is mounted on the existing control of the injection moulding machine, is then used to adjust the output in practical operation.

The control system does not interfere with the existing machine control system, but works autonomously. As control parameters, process information such as signals from potential-free contacts to the cycle, currents from the proportional valves and analog pump signals from the machine are tapped.

In addition to the high power savings, the main advantage of this technology is that the performance of the injection moulding machine is not limited, i.e. 100% maintained! The "Eta-Control®" performance adjustment function can be easily switched on or off by means of a key switch while maintaining 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 test operation. According to power measurements before the rebuild, about 41 kilowatts of this was actually needed for the production process. After the conversion and equipping with "EtaControl®" technology, only about 23 kilowatts were required for the same manufacturing process while maintaining all machine parameters. The 18 kilowatts of power reduction achieved was a very impressive result. Taking into account only 4800 annual production hours, this results in an annual power saving of 86,400 kilowatt hours. In addition, machine cooling and the transformer station are relieved, peak consumption is reduced and connected power for production expansions is freed up. For example, a single measure to reduce energy consumption has a number of consequences which have a positive effect on the overall energy balance.

"Although we had expected a lot from the ONI experts' presentation of the project, the result of the machine optimization at the pilot plant was stunning for us. After this top result, we commissioned the conversion of the machines proposed by ONI and were thus able to reduce the power consumption of these machines by around 40 percent. It's particularly gratifying that the costs for machine optimization will be self-financing in about 1.3 years as a result of the savings achieved in all areas," says Manfred Gante, summing up the use of EtaControl® technology.


Key Effect Tool Temperature Control

Quality, process stability and batch sizes in injection moulding production are essentially determined by mould temperature control. This insight is not new, but the results that can be achieved with product-oriented temperature control are often not seen due to a lack of comparability. Manfred Gante, on the other hand, quickly recognized the advantages of the dynamically operating "Rhytemper®" tool temperature control.

Backhaus manufactures high-quality plastic parts for a wide variety of industrial sectors. The quality of the products and the unit costs are, as everywhere, decisive factors when it comes to customer loyalty and competitiveness. For some products, it had been shown that conventional temperature control technology was difficult to achieve the required product quality and that the necessary short cycle times could not be achieved at all.

The consequence would have been a loss of substantial order volume or the writing of deep red figures, which in both cases would have caused major problems for the company. This problem had to be dealt with efficiently and the dynamic "Rhytemper®" temperature control system from ONI was used.

In order to obtain an objective comparison between conventional temperature control technology and dynamic systems, comparable conditions had to be created. The operating and production processes were optimized in advance and all possibilities of conventional temperature control technology were exhausted. Only after this optimization had been realized and results regarding quality, process stability and cycle time were available, production was continued using the "Rhytemper®" technology. The results in this area were very convincing. The cycle times between 10 and 22 percent, the energy consumption massive and the reject rate noticeably reduced. As an additional plus after the "Rhytemper®" installation, the load on the mold cooling circuit was noticeably reduced.

"From experience, we know that modern machine technology in combination with innovative tool development and a high-quality tool requires system-adapted tool temperature control. Only if all components involved in the core process work optimally can it be ensured that top products are continuously produced with the lowest possible energy consumption. For this reason, we have consistently applied the 'Rhytemper®' technology, made the best possible use of the advantages, improved our product quality a little and, above all, got our unit costs under control again," says Gante, explaining his experience with modern ONI temperature control systems.


Cooling machines to minimum, heating with waste heat

In the past, the cooling water for the injection moulds with a constant flow temperature of twelve degrees Celsius was produced throughout the year with refrigeration machines. However, chillers are energy guzzlers and ensure high power consumption and a correspondingly high electricity bill. At Backhaus, the ONI concept provides for cooling energy supply via chillers only during the warm summer months and a transitional period. Approximately 65 percent of the production hours are not used with chillers. The cooling energy supply for the tool circuit with an output of more than 500 kilowatts takes over a so-called winter relief during the transitional and winter periods. With this technology, existing free coolers completely or partially replace the chillers, depending on the outside air temperature, and the energy consumption is reduced to around two to three percent of the previous consumption value.

Instead of natural gas or heating oil, waste heat from the oil cooling of the injection moulding machines is used to heat the baking house free of charge. The temperature level of 35 degrees Celsius in the cooling circuit return flow is ideal for heating rooms. In the case of Backhaus, we are talking about a waste heat output of around 1000 kilowatts. As long as waste heat from the machines is available, heating is free of charge. Only a few hours a year, during which the machinery has to be switched off for maintenance work, is the heat supplied by a conventional heating system. "This heating concept from ONI has enabled us to reduce heating energy costs by around 90 percent. In view of further energy price increases to be expected, this technology cannot be rated high enough," says Manfred Gante, drawing a partial balance for this area.

"In the situation we were in, we were very lucky to have a partner like ONI by our side. They didn't just want to sell us something. The team around Wolfgang Oehm helped and advised us in various areas, even if there was nothing to sell...that's what we mean by partnership. The energy concept implemented by ONI has enabled us to get energy costs under control again and greatly improve our competitiveness. The fact that we're also making a significant contribution to reducing environmental impact is a welcome and wonderful side effect from which we all benefit," says Manfred Gante, summing up his experience in implementing the project with ONI.