Optimization of the morphological multi-layer system of micro components by means of a thermally highly flexible process strategy

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Inner componential properties substantially affect the components resulting properties within semi-crystalline thermoplastics. How inner-componential properties develop primarily depends on the cooling conditions of the component. These cooling conditions depend on the mold temperature due to the components minimal thickness, especially with regards to micro components. Due to a lack of knowledge on the causal relationships between selected tempering parameters, the establishment of inner properties and the resulting tribological properties, the development of tribologically optimal micro components has proven limited. In the research project "Processing induced morphological influences on the properties of thermoplastic micro gears" fundamental information regarding the influence of inner component properties on the resulting tribological properties were able to be obtained. Results showed that optimal tribological characteristics manifest in particular regions within the component with distinct, inner componential properties. By means of a conventional dynamic temperature strategy, which enables cooling at nearly constant cooling rates, higher cooling velocities along the components edges are achieved. Consequently, fewer distinct, inner componential properties and unfavorable tribological properties are emerged. While slower cooling rates could lead to better tribological properties, it would cause significantly longer cycle time. In order to reduce cycle times and to achieve optimal tribological properties, the mold systems cooling velocity needs to be adjustable flexibly. However, this has proven to be inadequate with current techniques. The aim of this transfer project is to study the aforementioned cooling conditions in micro injection molding, which ensure that every finite layer of a thermoplastic components cross section is exposed to the crystallization temperature area. Additionally, generating an idealized, theoretical injection molding temperature profile through process simulation is of fundamental importance. The ultimate aim is a targeted control of the mold temperature in order to optimize the inner-componential properties and, simultaneously, minimize the cycle time with a new, highly dynamic mold tempering strategy. Using the knowledge acquired to date, a demonstrator, here a micro gear, with homogenous, defined and optimal componential properties across the entire cross-section will be manufactured. With the help of obtained results, exploring new, fundamental questions becomes possible. Using the latest characterization methods for analyzing crystallization behavior with process-based cooling conditions allows establishing a process simulation model in which the micro-injection molding requirements can be ideally considered. Furthermore, the ability to manufacture micro-components with amorphous and highly temperature-resistant materials could also be considered.