Hybrid and multi-material components are used in numerous everyday applications: They can be found in household items, decorative elements, electronic parts and in components for the automotive industry. Hybrid components made of metal and plastic are often used in automobiles in particular. They serve as connecting elements, for example, in kinematic levers in car seats.
In conventional production, sheet metal and plastic components are combined in so-called insert injection molding by completely encapsulating sheet metal with plastic. In so-called outsert injection molding, the metal component is larger than the plastic part. The plastic is merely injected and covers part of the metal surface. Both processes involve a high energy input: The inserts have to be dispersed and cleaned. In addition, the plastic is heated and quickly cooled again after the molding process.
The majority of sheet metal processing small and medium-sized companies do not have in-house machinery to convert sheet metal components into a hybrid component. In current production scenarios, the stamping operation brings the heavy sheet metal inserts to the plastic injection molding company. Thus, not only the manufacturing process causes environmentally and climate-damaging emissions, but additionally also the transport.
In the "EcoHybridPro" project, the Fraunhofer IPT is developing a fast-cycle, energy-efficient production process that will enable the sheet metal processing industry to reduce energy consumption and CO2 emissions while saving costs.
The aim of the research project is a new manufacturing process chain: Undercuts are first created on the sheet metal by punching, bending or embossing. The sheet metal component can then be inductively heated and joined to the thermoplastic component. At the joining point, the plastic melts locally and flows into the undercuts of the sheet, where it finally solidifies. The manufacturing process chain for producing the sheet-based hybrid components can take place directly in the progressive die at the sheet metal processing company, and there is no need for transport to the injection molding company.
During the project, the research team analyzes the CO2 emissions of the individual process and development steps with the aim of achieving the greatest possible reduction. At the same time, this ensures that the findings can be transferred to comparable processes. The resulting guidelines for component design and joining processes, as well as the life cycle assessment framework, are also transferable to a wide range of components and serve to multiply the technology.
The most significant development within the project consists of flexibly usable modules that can be integrated into conventional progressive dies. So-called idle stages are to be provided in the die for this purpose. An induction module heats the joints of the component locally.
The joining module for the plastic components (e.g. bearing bushes, inserts such as brackets or stiffeners) provides a force- and position-controlled joining device with automated feeding into the die. Downstream, tool-integrated quality assurance of the hybrid component is performed by camera and image processing.
The Fraunhofer IPT is responsible for developing the pre-treatment steps for the sheet metal: From conventional sheet metal processing and inductive heating of the joining area to the development of the joining module for onsert elements such as holders and clips.
The integration of the individual process steps into the modular tool enables sheet metal processing companies to produce hybrid components independently without additional transport routes.
The aim of the project is to reduce overall energy requirements and cut CO2 emissions along the process chain by up to three quarters compared with the conventional process chain. The shorter cycle times mean that the production volume of cost-effective hybrid lightweight components can even be tripled.
Brose Fahrzeugteile SE & Co. KG, Bamberg
Federal Ministry of Education and Research
Funding code 01LY2013B