Doctoral Degrees (Industrial Engineering)

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Browsing Doctoral Degrees (Industrial Engineering) by Author "Booysen, Gerrie Jacobus"

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    Developing a certification framework to manufacture patient-specific implants using selective laser melting
    (2019-04) Booysen, Gerrie Jacobus; Van der Merwe, A. F.; de Beer, Deon; Stellenbosch University. Faculty of Engineering. Dept. of Industrial Engineering.
    ENGLISH ABSTRACT: Additive Manufacturing (AM) has proven to be an attractive alternative manufacturing process compared to Subtractive Manufacturing (SM) with many advantages, such as mass customisation, less material wastage and others, as listed in this dissertation. However, AM of certified implants does not have the same degree of documentation and standardisation as the SM process. As part of this research project, the problem statement stated that “in offering AM as an implant manufacturing solution, the complete process (design, manufacturing and post processing) had to be investigated in order to develop a certified manufacturing solution”. Objective 1 addressed the risk identification and ways to mitigate these risks through developing procedures, standard operating procedures (SOPs) and supporting documents. This can be seen as the technical certification of this certified manufacturing solution. In this project, a total of 68 risks were identified in the following areas: design, machine setup, powder handling, SLM process, part removal, density checks, heat treatment, non-destructive testing, destructive testing, surface finishing and coating, cleaning, sterilisation and packaging. The action plan was to mitigate these risks by developing procedures, SOPs, supporting documents and where needed, full machine and process validation. Objective 2 focussed on developing an integrated documentation framework, keeping traceability and repeatability in mind. Nineteen procedures, thirty-four SOPs, five supportive protocols, three machine validations and five process validations were identified and developed. Process and machine validations were developed that form part of the quality certification process and evaluated the consistency of the technical certification to prove repeatability and traceability of the products manufactured. Objective 3 focussed on identifying shortcomings in the framework and an in-depth analysis on ways to rectify these problems though continual improvement. Throughout this dissertation it was important not only to address some areas of concern but to explain the methodology behind risk mitigation, procedure and SOP development and validation and how these individual areas link to each other. The ISO 13485:2016 system is based on continual improvement principles which would mean that where new risks arise, the process of addressing these risks will be fast-tracked through this framework development. An initial process risk assessment was done before the framework development and after the framework development and it showed a significant reduction in the risk index. Four software, three hardware, two insourced process developments and one quality management system recommendations were compiled and four further research projects were identified as continual improvement.