Development of a digital production process for the economic manufacture of near-contour cooling systems; development of a casting and coring process for hybrid lost moulds.

Start of a research project within the framework of the “Central Innovation Programme for SMEs (ZIM)” under the sponsorship of the AiF with the partners voxeljet AG, the Fraunhofer Institute for Silicate Research (ISC) and the Fraunhofer Research Institution for Foundry, Composite and Processing Technology (IGCV):
“Development of a digital production process for the economic manufacturing of near-contour cooling systems; development of a casting and coring process for hybrid lost moulds.”

With this project, the consortium of SME companies aims to develop a novel process chain for the production of near-contour cooling systems – with previously unknown size and complexity – via casting processes. The main target markets are electromobility and power electronics, but also toolmaking for die casting, injection moulding and turbine construction.

The central market for near-contour cooling systems is electric motors due to the large quantities involved. During the project, the intended technological development will be verified using this example. The need to advance developments in this technology sector is presented below:

Environmentally friendly drive systems are an essential requirement for mobility systems due to increasing pollution in cities. Electromobility is a key to keeping emissions out of urban areas. This applies not only to vehicles for private transport but also to commercial vehicles in the public and commercial sectors.

The range of vehicles covers power classes from a few kilowatts for scooters to rail-bound vehicles with several megawatts of drive power. For all vehicles, however, the weight of the engine itself is relevant. The weight essentially determines the driving dynamics and the range of the vehicle. The weight of the engine is also linked to the overall energy balance of the vehicle.

The decisive key to reducing weight – i.e. increasing power density – is cooling the engine. Water-cooled systems are particularly effective. Their effectiveness depends on the heat transfer to the cooling medium. Here, a large surface area and the spatial proximity to the heat source are advantageous. As a technical implementation of this cooling, a cooling jacket is placed around the current-carrying, laminated stator, in which cooling lines are inserted (cooling close to the contour). The light metal aluminium is a suitable material for this housing, as it has the same properties of low density and good thermal conductivity.

The channel structures can be realised by producing the component through a casting process with lost cores. The cores are removed from the component after casting by shattering the core, which has already been thermally damaged by the casting, via vibration and impact.

Particularly high levels of complexity can be achieved using additive manufacturing processes. They also make it possible to reproduce the diversity of parts in the different performance and vehicle classes. Among the AM processes, binder jetting has the most favourable economic properties.
The resulting task for this project is the “development of a digital production process for the economic production of systems for contour cooling”. In the consortium, the sub-projects described below are being worked on in close cooperation: The Fraunhofer Institute ISC is researching a ceramic slurry for core production that can be processed in an AM process and also enables the desired properties of the component/core during the sintering process. The company voxeljet AG is developing a prototype printing system that enables the processing of ceramic slurry in an AM process on an industrial scale. The Fraunhofer IGCV experimentally determines all influencing variables on the component production process and makes the process comprehensible and optimisable through holistic modelling and simulation.
The foundry NRU GmbH is developing a process chain for the production of a metallic casting, with the decoring process for the novel, ceramic cores being the innovative core of the work. AMK, as an electric motor manufacturer and large company, is a potential user of the products created via the digital production process and does not itself provide any sub-innovation relevant to the funding.