Best practice: Simulation of special processes Optimisation of fluid injection technology for high-temperature resistant materials
© IKVFluid injection technology (FIT), including gas injection technology (GAIM) and water injection technology (WAIM), enables the production of complex, hollow plastic components. Thin-walled structures, larger component diameters and the predictability of component properties pose particular challenges when processing high-temperature resistant materials such as PPA and PPS. The aim of the project for a manufacturer of plastic pipes and associated components was to generate fundamental knowledge about process parameters in order to further develop the FIT for these requirements.
Development of a demontrator
Material analysis:
Comprehensive rheological, physical-thermal and mechanical properties of PPA and PPS were analysed. Methods such as DSC, TGA, TMA, pvT measurements as well as microscopy and spectroscopy were used to characterise the material processability.
Mould and process preparation:
The component geometry was defined (a typical media pipe) and the process parameters were prepared.
Moulding tests in the IKV technical center:
The first components were produced to test the suitability of the materials for the FIT. Inline analyses, such as residual wall thickness measurements and thermography, supported process optimisation.
Achieving thinner wall thicknesses through simulation and testing
Simulative process analysis:
Simulations were carried out with the aid of optimised component geometries and adapted meshing strategies. The aim was to improve residual wall thickness distributions and temperature profiles.
Design of Experiments (DoE):
A Design of Experiments (2³) was defined to investigate the effects of parameters such as injection pressure, fluid volume flow and material viscosity on wall thickness reduction.
Shaping attempts:
The simulation results were validated in the IKV, whereby the process parameters were specifically varied.
Realisation of larger component diameters (>40 mm)
Material tests with PA 66, PPA and PPS:
Tests with PA 66, an established material, were used as a benchmark. In parallel, PPA and PPS were tested as alternatives for larger diameters.
Process adjustments:
WAIM and PIT (Projectile Injection Technology) techniques were used to meet the requirements of larger cross-sections.
Analysis of the results:
In addition to residual wall thickness measurements and eccentricity measurements, computed tomography analyses and roughness measurements were carried out.
Basic knowledge for process development
Simulative DoE studies:
Variations in geometry, gas pressure and fluid delay times were investigated.
Test series:
Based on the simulations, further molded part tests were carried out to analyse the interactions between process parameters and component properties.
Results
A systematic relationship between material properties, process parameters and component results was established. Thinner wall thicknesses and larger component diameters were successfully achieved through optimised parameter combinations. The knowledge gained enables a targeted adaptation of the FIT for high-temperature resistant materials, which expands their application possibilities in industry.
Dr.-Ing. Christoph Zimmermann
Head of department Injection Moulding and Additive Manufacturing
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