E-Thesis 143 views
Advanced Manufacturing Techniques for Implantable Blood Pumps / RHODRI REES
Swansea University Author: RHODRI REES
DOI (Published version): 10.23889/SUThesis.68980
Abstract
Left Ventricular Assist Devices (LVAD) have been developed to provide an alternative to heart transplant surgery.The manufacture of these devices by traditional routes is expensive, time consuming and labour intensive due to the complexity and the level of precision required of each component. Despi...
| Published: |
Swansea University, Wales, UK
2024
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| Institution: | Swansea University |
| Degree level: | Doctoral |
| Degree name: | EngD |
| Supervisor: | Lavery, N. P.; Rees, A.; and Probert, D. |
| URI: | https://cronfa.swan.ac.uk/Record/cronfa68980 |
| Abstract: |
Left Ventricular Assist Devices (LVAD) have been developed to provide an alternative to heart transplant surgery.The manufacture of these devices by traditional routes is expensive, time consuming and labour intensive due to the complexity and the level of precision required of each component. Despite significant developments in LVAD functionality in recent decades, manufacturability remains an issue, particularly as functionality is directly influenced by component geometries. Subsequently, the manufacturability of current LVAD components exceed traditional manufacturing process capabilities.This thesis explores the application of Laser Powder Bed Fusion (L-PBF), an advanced manufacturing technique which have been identified as a potentially feasible alternative to subtractive manufacturing, due to its ability to rapidly produce complex shaped geometries. L-PBF technology also benefits from the ability to process Ti6Al4V, a biocompatible material used for the majority of the components of an LVAD.Thermally induced residual stresses can lead to geometric inaccuracy within L-PBF made components. Part geometry and size can influence the amount of geometric displacement caused by L-PBF process-induced residual stress. Geometric shape retention is critical for an LVAD application due to exacting tolerances and precision fit between components. An analysis of various L-PBF made Ti6Al4V geometries was to prove that part geometry and size is a key driver of stress-induced geometric displacement. The position of a part on the build substrate has minimal effect on the amount of displacement, introducing the ability to position components without risk of high scrap rates.An investigation of a novel diffusion bonding process using Hot Isostatic Pressing equipment to combine joining and porosity reduction of L-PBF components is shown to be successful in principle. However, the process was unsuitable for medical device manufacture due to poor process control, poor shape retention and process repeatability. This method is better suited for solid-to-powder bonding. |
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| Item Description: |
A selection of content is redacted or is partially redacted from this thesis to protect sensitive and personal information. |
| Keywords: |
Additive manufacturing, laser powder bed fusion, Ti6Al4V, left ventricular assist device, residual stress, geometric displacement, hot isostatic pressing, diffusion bonding. |
| College: |
Faculty of Science and Engineering |
| Funders: |
M2A, Calon Cardio-Technology Ltd |