Roth, Benedikt
Process and material-related processing limits of thermoplastic amorphous thin-walled components
Benedikt Roth
In the course of miniaturization of polymer components in the steadily growing application fields of electronics, optics and medical engineering, micro-manufacturing technologies are becoming increasingly important. However, the rising demand for components such as microfluidic chips, which often require complex three-dimensional surface structuring with the smallest possible wall thickness, places high demands on the underlying manufacturing process of injection molding. The challenges of this process involve reduced replication quality or short shots, low dimensional stability and dimensional accuracy, as well as warpage and anisotropy due to residual stresses and orientations.
The presented approach is to combine an injection-compression molding process with dynamic mold temperature control in order to maintain the flowability of the melt for the molding of surface structures and to ensure maximum tolerance quality with simultaneously reduced internal anisotropy over the entire part length by means of a homogeneous pressure distribution within the cavity.
The aim of this work is to investigate the process- and material-related processing limits of amorphous thermoplastics in order to derive a process window for the production of thin-walled and surface-structured components in injection-compression molding with dynamic mold temperature control. To this end, a comprehensive material understanding of the flow and solidification behavior of a polycarbonate is created on the basis of thermoanalytical methods. By implementing the generated data in a material model, the process is then analyzed by means of a numerical simulation. The findings of the material characterization and process simulation are linked to the component properties of replication quality, dimensional stability, residual stresses and orientations by means of processing experiments with variations in shear, melt temperature and cavity pressure and a process strategy for optimizing the target variables is derived from this.
pages: 160