Injection and compression molding

The injection and compression molding group specializes in the development of large-series processing technologies for flowable material systems. In addition to standard injection molding and compression molding processes, work is focused on single-stage resource- and energy-efficient direct processes, tailored local continuous-fiber reinforcement, and spraying processes.

Injection molding production unit for the processing of thermoset and thermoplastic material systems
© Fraunhofer ICT
Injection molding production unit for the processing of thermoset and thermoplastic material systems

Foam injection molding

Thermoplastic foam injection molding charges the polymer melt with a blowing agent that leads to the foaming of the molding compound in the cavity after injection. Together with our partners we develop material compositions and processes for foamed components using both chemical and physical (Mucell® / Direct-Foam) blowing agents.

Air flow produced by 2K injection molding and thermoplastic foam injection molding with a breathing mold
© Fraunhofer ICT
Air flow produced by 2K injection molding and thermoplastic foam injection molding with a breathing mold

Discontinuously reinforced thermoplastics

When compounding technology and injection molding are combined into a single process, plastic processors gain new, innovative options to improve the mechanical properties of injection molded components while saving energy and material costs. The gentle integration of fibers and resin via the compounding extruder also allows much higher fiber lengths to be achieved than in conventional injection molding. In compression molding, these materials can be processed with a productive and flexible direct process (two-machine technology). This technology offers particular flexibility in terms of the possible combinations of matrix materials and the reinforcing fibers used, as well as shorter cycle times during manufacture. In addition, the back-molding of metallic inserts or continuous-fiber-reinforced thermoplastic semi-finished products offers significant potential for further developing this material class towards its application in structural components.

MoPaHyb – Pilot plant with hydraulic downstroke press and long-fiber injection molding module
© Fraunhofer ICT
MoPaHyb – Pilot plant with hydraulic downstroke press and long-fiber injection molding module

Injection molding of thermosetting fiber composites

In comparison to thermoplastics, thermosetting (cross-linking) polymers have advantages in terms of media and temperature stability which make them attractive for high-performance applications under demanding conditions. For example, it is possible to substitute aluminum die casting with free-flowing, thermosetting molding compounds based on phenolic and epoxy resins, leading to weight and cost reduction.

Prototype of an injection-molded lightweight cylinder casing of an engine block made from glass-fiber-reinforced phenolic resin (lightweight combustion engine)
© Fraunhofer ICT
Prototype of an injection-molded lightweight cylinder casing of an engine block made from glass-fiber-reinforced phenolic resin (lightweight combustion engine)

Sheet molding compound (SMC)

SMC components are finding increasing application in the automobile and utility vehicle sectors. They are associated with various advantages such as low density, high thermal and chemical stability, dimensional stability and an achievable class-A quality surface appearance. SMC enables lightweight construction solutions in application areas that are characterized by stringent requirements regarding mechanical, chemical and thermal stress.
We are active in the field of material and process development for the compounding and extrusion compression molding of SMC. This includes for example formulation development, the implementation of novel resin systems and reinforcing fibers, the development of new production units for semi-finished products and improved process control in component manufacture. The main focus is class A surfaces, lightweight SMC, locally reinforced SMC components, and the processing of nanoparticles and natural and carbon fibers.

SMC, shown in the underbody of a car. Fiber optic SMC was used for the ribs. Load paths are reinforced with UD-CF prepeg. The prepreg was automatically draped on a Dieffenbacher Preform-Center using a special resin (hybrid resin/UPPH resin). This enables the production of stiff and dimensionally stable reinforcement structures and at the same time a chemical bond to the SMC in co-molding.
© Fraunhofer ICT
SMC, shown in the underbody of a car. Fiber optic SMC was used for the ribs. Load paths are reinforced with UD-CF prepeg. The prepreg was automatically draped on a Dieffenbacher Preform-Center using a special resin (hybrid resin/UPPH resin). This enables the production of stiff and dimensionally stable reinforcement structures and at the same time a chemical bond to the SMC in co-molding.

Long-fiber-reinforced polyurethanes

Polyurethane fiber spraying is a flexible process for the manufacture of long-fiber-reinforced polyurethane components. With the possibility to vary fiber lengths and fiber contents, and to spray different polyurethane systems, this method makes it possible to locally adjust the property profiles of components. Furthermore, the polyurethane fiber spraying process enables the low-cost production of sandwich structures.

Through combination with local reinforcement structures, the institute is working to develop new application areas for polyurethane structural components in a multi-material design.

Prototype PURtrain shows a function-integrated train body segment in a multi-material design - hybrid sandwich construction for rail vehicles
© Fraunhofer ICT
Prototype PURtrain shows a function-integrated train body segment in a multi-material design - hybrid sandwich construction for rail vehicles