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Title: Hot embossing of polymeric tubular micro-components
Author: Zhao, Jie
ISNI:       0000 0004 6061 9753
Awarding Body: University of Strathclyde
Current Institution: University of Strathclyde
Date of Award: 2016
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Technical and market demands of tubular micro-components have led to the development of a hot embossing process and corresponding machine for shaping polymeric micro-tubes. The targeted tubular micro-components are of an initial outer diameter of 1.6mm or below, and have reduced inner feature in the micron meter ranges. The proposed process feasibility study was supported by: 1) FE simulations using data obtained from material characterisation tests and 2) forming experiments and quality assessment of the formed components. Formability of more than ten types of polymeric micro-tubes were determined and their failure forms discussed. Furthermore, three forming mechanisms, namely plastic deformation, material flow and fusion bonding were identified and studied in detail. These studies allowed a fully functional machine to be developed, which has proved to be able to reliably produce 20 pieces parts per-minute when used with a continuous tube feeding system. The machine enabled a detailed process parameters study to be conducted in order to establish the factors influencing the final forming result. These consisted of two categories: the first category was Geometry Factors, which include the die-cavity geometry and tube inner/outer diameter ratio; the second category was Process Parameters, which include the forming temperature, maximum applied force, embossing velocity and dwelling time. The samples obtained were then evaluated through morphology examination, size measurement, microstructure and material flow analysis. The PTFE-a (outer diameter 1.2mm and inner diameter 0.6mm) and PP-a (outer diameter 1.3mm and inner diameter 0.6mm) micro-tubes have been successfully fabricated with desired features at temperatures of 200°C and 100°C respectively. The Polypropylene (PP) is considered as the most preferable material for hot embossing of tubular micro-components, due to its good ductility, low melting temperature and low viscosity. The results suggest that the proposed design can produce good performance with the correct combination of process parameters, tools and machine. The main outcomes from this research are: a novel micro-manufacturing process, material characterisation of polymeric micro-tubes, identification of the key hot embossing process parameters and their effects on the quality of the formed parts (especially the micro-scale features), a mass production solution, and a prototype desktop machine for industrial applications.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral