Process development for the recycling of organic sheet blanks with direct implementation in the hybrid component manufacturing process with additional evaluation

In lightweight construction, thermoplastic fiber composites are increasingly being functionalized. The injection molding process for thermoplastics in combination with continuous fiber-reinforced thermoplastics (organic sheets) is particularly suitable for this. For the production of hybrid components, a constant amount of waste is produced due to the specific configurations and load-related orientation in the later component. Within the scope of the project, a suitable process is to be developed to implement these offcuts as injection molding components in the hybrid component process. The aim is to achieve a closed cycle with high added value and high quality of the end result. In particular, the interactions of the material properties, the machine technology and the economic efficiency are to be investigated, taking into account the savings potential through material-efficient manufacturing and processing technologies of the entire process chain.

Background and Content

For the production of so-called hybrid components, the organic sheet blanks are heated by means of infrared radiators and inserted into the injection mold and formed. In the process, functional elements are injected onto or through the organic sheet. However, approx. 10-30% waste must be expected when cutting the organic sheets to size. At Bond Laminates in particular, 10 tons of offcuts are produced per month. The reason for this is, on the one hand, the specific geometries required and the preparation of the blanks by means of cutouts and apertures, and on the other hand, care must be taken during cutting to ensure that the orientation of the continuous fibers in the subsequent hybrid component is appropriate for the load. Currently, the offcuts, which have a negative impact on both the costs and the environmental impact of the fiber composite plastic, are recycled for energy. Thus, the material recovery potential (recycling potential) of the resource-intensive fiber composite material is unused. In the meantime, however, fiber-reinforced composites are no longer accepted by numerous operators of waste incineration plants because the non-combustible fibers cause clogging of the exhaust air filters. This poses a significant problem for the manufacturers and users of these hybrid lightweight components. This is the point in the value chain where the research project comes in.

Project Objective

The project aims to develop a closed-loop strategy.
The results of this research project will also be used to develop an optimum process for processing organic sheet offcuts as economically as possible without any loss of mechanical properties compared with conventional injection-molded granules, and for integrating them into the injection-molded series process.
The following research results are expected:

  • High added value with the highest possible quality
  • Incorporation directly into the process chain for the production of hybrid components
  • Highest possible fiber lengths in the end product
  • Most economical and ecological preparation and utilization of organic sheet waste
  • Comparison and evaluation of process control
  • Extensive analysis of mechanical material characteristics in the recyclate as well as in the later hybrid component

Project Flow

The project is divided into three phases:

  • In Phase I, basic studies will be carried out on the crushing, processing and dosing of the organic sheet offcuts.
  • In Phase II, a comprehensive economic analysis of the recycling process and holistic evaluation of the environmental relief effects by means of Life Cycle Assessment (LCA) will be carried out.

  • In Phase III, the mechanical parameters of the results are considered and analyzed.


Organic sheet processing is increasingly being used in the series production of vehicle components. Depending on the component, the waste of organic sheets is approx. 10-30%, a fact which generates a high demand for research, both ecologically and economically. In general, the feasibility of recycling organic sheets is known due to the material properties. However, there is a high need for research to investigate the interactions between the complex material structure, the machine technology for preparation and recycling, and the economic factors of the multi-stage value chain. In this value chain, the offcuts of the continuous reinforced semi-finished product are to be recycled into a long glass fiber reinforced injection molded component for functional elements in organic sheet processing directly in the manufacturing process, without reductions in mechanical properties. This implementation in the manufacturing process, taking into account the mechanical properties, exhibits a high degree of innovation. The focus here is on the economic and ecological added value resulting from the incorporation of a high proportion of "production waste".

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