Projekt Antriebsstrang 2025
Energy-efficient process chains for the production of a friction-, weight- and service life-optimised drivetrain
Climate change and energy policy are two major issues in current politics. This is also reflected in the calls for funding projects. Many of the research projects are designed to save energy or reduce CO2 emissions. A major research project at Leibniz Universität Hannover came to an end on 28 February 2022. Together with project partners, the Institute of Production Engineering and Machine Tools (IFW), the Institute of Machine Design and Tribology (IMKT) and the Institute of Technical Combustion (ITV) worked on the development and production of an energy-optimised car powertrain.
In the project "Powertrain 2025 - Energy-efficient process chains for the production of a friction-, weight- and service life-optimised powertrain", different process chains for the production of representative components of a powertrain (cylinder liner, drive shaft and pumps) were investigated. The aim of the project was to utilise existing research results in order to apply them in combination in highly productive process chains in such a way that energy can be saved significantly in the production phase, but the drivetrain also gains significantly in efficiency in the utilisation phase and emits less CO2.
The starting point for this project was the idea of utilising surface treatment processes that either already exist or have been thoroughly investigated but are not yet in widespread use in order to achieve the goal of energy efficiency. The targeted use of smooth or deep rolling, mechanical surface hammering or even microstructuring or honing was investigated here. Combined with ultra-modern process chain controls, these processes can also be used productively in large-scale production and contribute to the energy and resource efficiency of the powertrain.
We spoke to three IFW scientists about the project and had them explain the aim of the project and, above all, the results.
Hello you three, thank you for taking the time for this short interview. We wanted to talk a bit about our joint research project "Powertrain 2025 - Energy-efficient process chains for the production of a friction-, weight- and service life-optimised powertrain". Benjamin, as project manager, can you please give us an overview of the project? What was it about and what was the aim of the project?
Benjamin: In the Powertrain 2025 project, innovative process chains and hybrid tool concepts are being developed to make the manufacturing and utilisation phase of powertrain components more energy and resource efficient. In addition, an ecological assessment of the developed process chains is being carried out. The aim is to increase energy and resource efficiency in the production and utilisation of drive components. This is intended to make a contribution to climate protection.
Oliver: So basically it's about using existing technologies in large-scale production to save energy in the production phase, but also in the later utilisation phase, right? Christopher, can you explain the different technologies that will be used in the project?
Christopher: The technologies we are using are all from the field of manufacturing technology. They range from additive manufacturing and machining to finishing processes such as deep rolling, roller burnishing and honing. Conventional turning and milling processes are used in machining, but also innovative microstructuring and mould turning processes.
Oliver: And how are the two surface treatments deep rolling and microstructuring actually used in the project and what are the results? Can you explain two examples from the project?
Christopher: Deep rolling is used to machine drive shafts. We were able to reduce the wall thickness of drive shafts and increase their service life at the same time. This is possible because the machining process specifically introduces internal stresses into the edge zone of the workpiece. This hardens the material and increases the service life despite the reduced wall thickness. This reduces the weight and minimises the probability of component failure.
We use microstructuring for another aspect of application behaviour: friction behaviour. We incorporate microstructures into the surface of cylinder liners in order to reduce friction between the liner and piston. The effect is that we prevent the failure of the lubricating film through the lubrication pockets and thus reduce wear and friction losses. As a result, we can reduce friction power by up to 20 %, resulting in fuel savings of 1 %. Scaled to the entire volume of large industrial engines, e.g. in ships, mining or generators, the savings quickly add up. If you add the microstructuring of constant velocity joints in the drivetrain, the reduction in friction alone can save 760,000 tonnes of CO2.
Oliver: Okay, that was basically the technological level, what properties the processes produce on the components. What does it look like on the second level? How do the processes fit into large-scale production? What trends do you see here?
Benjamin: The trends we are seeing are the omnipresent automation and digitalisation of process data, which is used for control and monitoring, for example. This not only offers productivity increases, but also energy-saving potential, e.g. by reducing rejects or shortening process chains. For example, by eliminating hard machining. These processes can be used in large-scale production, as anomalies can be easily detected in these established processes. Of course, the implementation is then carried out by the companies, but we can solve the challenges together by working together.
Oliver: Leon, and this is where you come in. The project has shown that deep rolling and microstructuring have enormous advantages for component properties and that these additional processes can be integrated into large-scale production in a highly productive manner. But what impact does the whole thing have on energy consumption? Can you report on the project results?
Leon: Sure, I'm happy to do that! Within the overall Powertrain 2025 project, we picked out three different target variables that we wanted to improve specifically through our research work. These are the weight of the drivetrain, friction and manufacturing energy. Reducing the weight of the drivetrain not only saves raw materials, but also reduces weight-dependent pollutant emissions during the service life of a vehicle.
Within the project, we managed to reduce the weight of the drivetrain by 6 kg, which leads to an annual savings potential of almost 196,900 tonnes of CO2. Christopher has already mentioned the targeted introduction of microstructures. This enabled us to minimise friction by 759,000 tonnes of CO2. Finally, by developing innovative process chains for the production of a drivetrain, we have been able to reduce manufacturing energy by 12,905 MWh/year. This corresponds to a potential saving of 35,241 tonnes of CO2. Taken together, we therefore have an annual savings potential of 991,141 tonnes of CO2 within Germany. I think that's already impressive and shows the potential of our research work very well!
Oliver: Ok, if the savings potential is so great, do you already have projects or requests to transfer the results? What are the major challenges for implementation? Or specifically, how should the transfer to the real world happen now? What do the OEMs in the project have to say about this?
Benjamin: The greatest potential exists in the production of drive shafts for cars, because this is where the largest quantities are produced, which are also largely independent of the type of drive (electric, combustion). In addition, this is where we can most easily transfer the weight savings achieved to other component variants because we have only looked at one version so far. The challenge here is primarily the intervention in highly automated large-scale production process chains and also the investments. The processes set up, for example deep rolling, are already very close to industrial reality, but the final detailed steps have to be carried out in close coordination with the partners' production departments.
Oliver: Thank you for talking to us and thank you for the excellent collaboration on the joint project. The collaboration has always been great fun for us and for me personally.
Further information on the topic of deep rolling can be found in an article in the Industrieanzeiger on the research project with Volkswagen - 3D printing suitable for automotive series production. The Institute of Production Engineering and Machine Tools (IFW) at Leibniz Universität Hannover and Volkswagen AG in Braunschweig are cooperating on the project with the involvement of ECOROLL AG Werkzeugtechnik.
