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Development of novel applications for the electron beam texturing and Surfi-Sculpt® processes
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Pinto, Thomas Matthew (2020) Development of novel applications for the electron beam texturing and Surfi-Sculpt® processes. EngD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b3679348
Abstract
The electron beam texturing (EBT) and Surfi-Sculpt® processes are transformative surface modification technologies used to create customised complex geometrical surfaces rapidly and at low-cost to improve the performance of a surface. These processes are neither additive nor subtractive but rely on the interaction between a workpiece and a power beam, with its subsequent deflection, to locally melt and move the parent material on the surface in the opposite direction to the deflection to create protrusions and corresponding intrusions. The complex novel surface textures and features produced, in many cases, cannot viably be manufactured by other techniques. However, market barriers have restricted the industrial adoption of these processes due to a limited amount of performance data demonstrating the benefits in specific application areas. Furthermore, a lack of fundamental understanding of how features are formed during the processes as well as limited knowledge management had added technical barriers.
In seeking to address these issues, a series of studies and literature reviews were conducted to support improved control of the EBT and Surfi-Sculpt processes and to increase understanding of the physics. Data analysis resulted in the creation of formulas for the prediction of feature heights in three materials. A bespoke technique was developed to record high-speed video of the EB Surfi-Sculpt process from within the vacuum chamber where five distinct phases of feature formation were identified: initial melt track; expansion of feature base and height; increase of height; bridging; and over melting with potential decrease of height. Fundamental analysis of the images was conducted before a model was proposed enabling the prediction of the flow of molten material based upon Marangoni effects, i.e. resulting from differences in surface tension across an interface during the initial beam-material interaction and subsequent beam translation.
Two case studies investigated specific novel applications of the processes for use on liquid cold plates (LCPs) and uncemented acetabular cups for orthopaedic implants. Prototype components were manufactured through the development and optimisation of parameters and resultant surfaces; these were assessed against existing technologies. The prototype LCP demonstrated a reduction in manufacturing time of approximately 40 % per component, increased heat transfer allowing more power in the electronic components being cooled and increased efficiency by 100 % without size or weight penalties. This indicated the ability to use a 50 % smaller LCP for the same cooling power. With the uncemented acetabular cup, an increased coefficient of friction of over 50 % compared with an existing technology was evidenced which created a self-rasping and bone graft generating surface and demonstrated application of a surface to a prototype component with 18.2 seconds beam on time.
A directory and selection tool (Surfi-Sculpt catalogue) was developed which captured all required parameters for the manufacture of specific surfaces including geometrical characterisation, an image of the resultant surface and a search capability to enhance rapid identification and manufacture of surfaces. This improved knowledge management and underpinned the advancement of these technologies.
A mathematical model was proposed to enhance the creation and optimisation of deflection pattern files with associated deflection frequencies for the EBT and Surfi-Sculpt processes. The effect of different materials on the penetration depth of the beam and subsequent feature height variation was explored. The benefit of this work will be a reduction in empirical development and the future creation of a framework for improved automation of the processes which could embed this knowledge into pre-processing software.
In conclusion, this work has directly advanced the EBT and Surfi-Sculpt processes by overcoming many of the market, technical and knowledge management barriers.
Item Type: | Thesis (EngD) | ||||
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Subjects: | T Technology > TA Engineering (General). Civil engineering (General) T Technology > TK Electrical engineering. Electronics Nuclear engineering |
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Library of Congress Subject Headings (LCSH): | Electron beams -- Industrial applications, Microfabrication, Microfabrication -- Technological innovations, Surfaces (Technology), Cold plates (Electronics) | ||||
Official Date: | October 2020 | ||||
Dates: |
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Institution: | University of Warwick | ||||
Theses Department: | Warwick Manufacturing Group | ||||
Thesis Type: | EngD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | Barnes, Stuart (Professor of engineering) ; Neailey, Kevin ; Ward, Anita | ||||
Sponsors: | TWI Ltd ; Great Britain. Technology Strategy Board ; Seventh Framework Programme European Commission | ||||
Format of File: | |||||
Extent: | xiii, 187 leaves : illustrations | ||||
Language: | eng |
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