Background of the Project
Global trends are forcing industry to manufacture lighter, safer, more environmentally friendly, more performant and cheaper products:
The manufacturing systems engineering sector is aiming at better performing machine components; increased integration of functionalities provides a competitive advantage and, in the transport sector, weight reduction is pursued.
As a consequence, all industrial branches are continuously seeking innovative approaches in the fields of materials development, manufacturing systems engineering and processing technologies. Scientific research as well as successful industrial case studies show that the high performance requirements of innovative products can only be met if the material properties are ideally adapted to the requirements, the load profile and the function of each individual component. Frequently, this can only be achieved by combining different and sometimes exotic materials as impressively shown in the “Superlight-Car” project, funded by the European Commission under the 6th Framework Programme (see Figure 1) or to give an example of a real industrial application in the multi-material body of the Audi A3.
Lesemann, M.; Sahr, C.: SuperLIGHT-CAR – The Multi-Material Car Body. 7. LS-DYNA Anwenderforum, Bamberg, 2008.
Joining by Electromagnetic Forming (EMF),
also called electromagnetic pulse joining or welding, is a promising innovative technology. EMF is a high-speed forming technology using pulsed magnetic fields for forming electrically-conductive tube or sheet metal workpieces without mechanical contact between tool and workpiece. Depending on the interaction with additional components, apart from mere shaping processes, also joining by EMF is possible. It can be used for:
EMW is possible for similar and dissimilar material combinations, including those which are difficult or impossible to join using conventional processes. The joint is formed without heat, but due to the impact of the joining partners. Therefore, numerous of the disadvantages of other technologies can be avoided.
If the workpieces are impacted with high velocity and under a certain angle, a jet is created along the materials’ surface before they contact. This jet removes surface contaminants, such as oxide films, which eliminates the need for pre-process cleaning. Frequently, no pre-weld cleaning is required at all
Despite of the described benefits, the technology is hardly known in the metal processing industry and applications are limited to very specific case studies.
Global Project Aim and Benefit
The focus of JOIN’EM will be on joining aluminium and copper in order to improve performance and reduce costs of electrical as well as heating and cooling applications in different industrial sectors, including machine and equipment construction (for example for the food industry), automotive and transport (trucks, buses, trains, etc.), white goods, air-conditioning and high power electronics.
However, also the transferability of the conclusions to other relevant material combinations will be regarded, so that all industry sectors dealing with multi-material joints can benefit from the findings. This will be delivered by the combined development of the joining processes, finite-element modelling, material and joint characterisation and testing, both on small-scale laboratory tests and full scale trials. In particular, JOIN’EM will:
Develop innovative methods for joining dissimilar metals, which will allow improved manufacturing or new products. These innovations will also deliver increased product reliability, a longer lifetime of the components and welds, combined with a reduction of maintenance costs.
Facilitate an increased use of dissimilar metal combinations. Up to now, this has been prevented due to the difficulty of welding multi-material-combinations using conventional welding processes. Overcoming this obstacle will open up a wide potential of manufacturing functionally optimised, lightweight and high- performant products, which are not possible today.
Increase productivity and reduce costs for realising hybrid components using EMW: joining operations are performed faster, more efficiently and robustly, thus more economically, due to a less expensive production process while guaranteeing better quality.
Permit the achievement of lower life cycle cost of a product.
Enable the use of the environmentally-friendly EMW process. The process needs no fluxes or shielding gases and produces no harmful smoke, fumes or slag, thus reducing the overall environmental impact.
Advances Brought by JOIN’EM
Up to now, tool design and manufacturing was carried out by means of trial and error and experience, but without substantiated knowledge and consideration of the service behavior of the materials and components. Within JOIN’EM, consolidated knowledge for a more professional approach will be provided by:
Quantitative prediction of the electrical, mechanical and if necessary also thermal loads acting on the tools by means of numerical simulation. For this purpose, numerical simulation of EMW will be further developed, especially focusing on a more detailed modeling of the tool components, which will be considered as deformable structures and no longer as rigid bodies only.
- Determination of data about the fatigue performance of materials applied in tool manufacturing. This concerns mainly copper alloys for the conducting parts and fibre-reinforced plastics for the housing components. Data about fatigue performance of copper alloys is scarce in literature.
- Lifetime prediction of tools and tool components based on numerical simulations.
- Improvement of the fatigue behaviour and lifetime by means of suitable treatments. This will be based on the proved enhancement of the fatigue life due to surface treatment by shot or laser peening and delayed fretting fatigue by cryogenic treatment or chromium nitride coating.