Plastics are playing an increasingly important role in the substitution of metallic materials. Due to the low material costs of BMC compared to high-performance thermoplastics as well as the processing in the injection moulding process, high-strength and shrinkage-free components with low weight can be produced cost-effectively in almost any geometry.
The aim of this research project is to develop a fibre damage model that maps the material-specific influences in the injection moulding process of BMC moulding compounds (material composition, process parameters and screw geometry) on fibre length reduction. During the processing of BMC moulding compounds in the injection moulding process, the added long glass fibres with an initial length of 3 mm to 12 mm are significantly shortened due to the dissipative input in the processing procedure, which leads to a reduced utilisation of the material potential.
To validate the model, the calculated fibre lengths from the developed BMC fibre damage model are compared with the fibre lengths actually determined. For this purpose, dead-stop investigations are used to determine the fibre damage via the screw conveyance of the suspension. To check the fibre length reduction, samples are taken at defined points in the screw conveyance and examined by means of fibre length scans.
Taking into account the main influencing factors on fibre damage shown in the model, a fibre-protecting process technology is developed and put into operation. Finally, the real fibre damage is examined and compared with the calculated results of the model.
In the development of the novel process technology, compatibility with common BMC injection moulding machines must be ensured in order to give BMC processors access to the new technology of the two-piston injection moulding unit.