Process Chain of Injection Moulding and Additive Manufacturing for Hybrid Parts

Abstract

To achieve lightweight properties, a process for the local reinforcement of injection-moulded parts using additive manufactured continuous fibre reinforced inserts was developed. The process is based on the additive manufacturing (material extrusion) of semi-finished products (inserts) made of pre-impregnated continuous fibres, which are inserted in a defined position of the injection mould and then over-moulded with a compatible polymer matrix. Due to the manufacturing method of the inserts, a material, form and frictional bonding between the fibres and the polymer matrix can be realised. By choosing a specific positioning of the inserts resp. the continuous fibres, one can achieve a significant lightweight construction potential and the targeted elimination of process-related weak points such as weld lines of the injection-moulded parts. A virtual development process using digital product development tools were applied for the construction of a concrete application example. A combination of topology optimisation and finite element analysis (FEA) was used to determine the load- and material-optimised design. For the simulation and optimisation of hybrid parts a new method of virtual development and definition of material models for additively manufactured components was developed. The validation of the process chain for hybrid parts was carried out using a test setup that represents real load situations of an automotive part. The technical analysis of the hybrid part showed a weight saving of 19.5% compared with the reference part. Regarding the critical load case (load from above), a 38.1% lower deformation was achieved. The specified maximum load and deformation limits were maintained in the use case. In addition, in the weld line area malfunction was avoided by the continuous fibre-reinforced insert.