Critical powder characteristics for high quality laser powder bed fusion

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dc.contributor.advisorBlaine, DCen_ZA
dc.contributor.authorDe Waal, Aen_ZA
dc.contributor.otherStellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.en_ZA
dc.date.accessioned2024-02-26T11:39:21Zen_ZA
dc.date.accessioned2024-04-26T12:20:12Zen_ZA
dc.date.available2024-02-26T11:39:21Zen_ZA
dc.date.available2024-04-26T12:20:12Zen_ZA
dc.date.issued2024-02en_ZA
dc.descriptionThesis (MEng)--Stellenbosch University, 2024.en_ZA
dc.description.abstractENGLISH ABSTRACT: The acceptance of Additive Manufacturing (AM) as a reliable manufacturing technology in South Africa and globally, is still limited. This is due to concerns about replicability and variations in quality. Efforts to enhance AM standards aim to address these challenges by focusing on understanding raw metal materials. Characterizing and comprehending powder materials pose significant challenges for the AM community, especially in technologies utilizing a powder bed. Powder behaviour during spreading is a relatively new research area that is not fully understood. Academia and industry practitioners are actively exploring these concepts to enhance AM's quality, reliability, and replicability. This research aims to identify and validate critical metal powder characteristics that include the powder morphology, particle size distribution, moisture content, flowability and various densities of the powder, and their relation to efficient powder spreadability characteristics that effectively describe the powder layer quality. Furthermore, the relationship of these characteristics to consistently building high-quality final parts using the AM technique known as laser-powder bed fusion (L-PBF) must be established. The results obtained in this project aid the Collaborative Programme in Additive Manufacturing (CPAM) strategy that is focused on identifying L-PBF as a reliable and accepted manufacturing technique in South Africa as well as globally. Standardised and customised powder characterisation testing was conducted on different powders that included two spherical powders that are designed for LPBF, namely, commercially pure titanium (CP Ti) and Ti-6Al-4V, as well as a CP Ti powder that is produced by the hydride-dehydride process (HDH), that displays an angular particle shape and is not typically used for L-PBF. The results from the powder characterisation experiments successfully identified critical powder characteristics that influence powder spreadability and, consequently, the as-built part quality. Thus, the impact of powder characteristics on the spreadability of the powder and the resultant direct effect on the powder layer quality is demonstrated, emphasizing the importance of aligning spreading parameters with the critical powder characteristics that include powder flowability, packing ability, and settling rate for consistent, high-quality powder layers. A criteria system that validates whether a powder is suitable for L-PBF, based on the powder characteristics, was identified, and used to determine whether a mixture of the spherical and HDH CP Ti powders is useable for L-PBF as a more cost-effective solution. It was determined that a 90:10 mass ratio mixture of the spherical to HDH CP Ti powders delivered suitable spreadability results for L-PBF.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Die aanvaarding van laagvervaardigingstegnieke (AM) as 'n betroubare vervaardigingstegnologie in Suid-Afrika en wêreldwyd is steeds beperk. Dit is as gevolg van kommer oor die herhaalbaarheid en variasies in die kwaliteit. Pogings om AM-standaarde te verbeter het ten doel om hierdie uitdagings aan te spreek deur te fokus op die begrip van rou metaalmateriale. Karakterisering en begrip van poeiermateriaal stel beduidende uitdagings vir die AM-gemeenskap, veral in tegnologieë wat van 'n poeierbed gebruik. Poeiergedrag tydens verspreiding is relatief 'n nuwe navorsingsarea wat nie ten volle verstaan word nie. Akademie en kundiges in die industrie ondersoek hierdie konsepte aktief om AM se kwaliteit, betroubaarheid en herhaalbaarheid te verbeter. Hierdie navorsing het ten doel om kritieke metaalpoeierkenmerke te identifiseer en te valideer wat die poeiermorfologie, deeltjiegrootteverspreiding, voginhoud, vloeibaarheid en verskeie digthede van die poeier insluit, en hul verband met doeltreffende poeierverspreidingseienskappe wat die poeierlaagkwaliteit effektief beskryf. Verder moet die verwantskap van hierdie kenmerke met die konsekwente hoë kwaliteit van finale dele, wat deur die AM-tegniek bekend as laser-poeierbed fusie (L-PBF) gebou word, vasgestel word. Die resultate wat in hierdie projek verkry is, help die Samewerkende Program in Laagvervaardigingstegnieke (CPAM)-strategie wat daarop gefokus is om L-PBF as 'n betroubare en aanvaarde vervaardigingstegniek in Suid-Afrika sowel as wêreldwyd te identifiseer. Gestandaardiseerde en pasgemaakte poeierkarakteriseringstoetse is uitgevoer op verskillende poeiers wat twee sferiese poeiers ingesluit het wat vir L-PBF ontwerp is, naamlik kommersieel suiwer titaan (CP Ti) en Ti-6Al-4V, sowel as 'n CP Ti-poeier wat vervaardig word deur die hidried-dehidried-proses (HDH), wat 'n hoekige deeltjievorm vertoon en nie tipies vir L-PBF gebruik word nie. Die resultate van die poeierkarakteriseringseksperimente het kritiese poeierkenmerke suksesvol geïdentifiseer wat poeierverspreibaarheid beïnvloed en, gevolglik, die soos-gebou onderdeel kwaliteit. Die impak van poeierkenmerke op die verspreibaarheid van die poeier en die gevolglike direkte effek op die poeierlaagkwaliteit word so gedemonstreer, wat die belangrikheid beklemtoon om verspreidingsparameters in lyn te bring met die kritieke poeierkenmerke wat poeiervloeibaarheid, pakvermoë en afsaktempo insluit vir konsekwente hoë kwaliteit poeierlae. 'n Kriteriastelsel wat valideer of 'n poeier geskik is vir L-PBF, gebaseer op die poeierkenmerke, is geïdentifiseer en gebruik om te bepaal of 'n mengsel van die sferiese en nie-sferiese CP Ti poeiers bruikbaar kan word vir L-PBF as 'n meer koste-effektiewe oplossing. Daar is vasgestel dat 'n 90:10 massaverhouding mengsel van die sferiese tot HDH CP Ti poeiers geskikte verspreibaarheidsresultate vir L-PBF gelewer het.af_ZA
dc.description.versionMastersen_ZA
dc.format.extentxix, 126 pages : illustrations.en_ZA
dc.identifier.urihttps://scholar.sun.ac.za/handle/10019.1/130293en_ZA
dc.language.isoen_ZAen_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subject.lcshAdditive manufacturingen_ZA
dc.subject.lcshTitanium powderen_ZA
dc.subject.lcshLasers -- Industrial applicationsen_ZA
dc.subject.lcshLaser powder bed fusionen_ZA
dc.subject.lcshUCTDen_ZA
dc.titleCritical powder characteristics for high quality laser powder bed fusionen_ZA
dc.typeThesis en_ZA
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