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Development of additively manufactured self-lubricating rolling element bearings for warehouse-centric AGVs
Thesis (MEng)--Stellenbosch University, 2024.
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Stellenbosch : Stellenbosch University
2025
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| _version_ | 1867613841789026304 |
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| access_status_str | Open Access |
| author | Mashayamombe, Tafadzwa |
| author2 | Matope, Stephen |
| author_browse | Mashayamombe, Tafadzwa Matope, Stephen |
| author_facet | Matope, Stephen Mashayamombe, Tafadzwa |
| author_sort | Mashayamombe, Tafadzwa |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description |
Thesis (MEng)--Stellenbosch University, 2024. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/131824 |
| institution | Stellenbosch University (South Africa) |
| last_indexed | 2026-06-10T12:42:33.557Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/131824 Development of additively manufactured self-lubricating rolling element bearings for warehouse-centric AGVs Mashayamombe, Tafadzwa Matope, Stephen Stellenbosch University. Faculty of Engineering. Dept. of Industrial Engineering. Additive manufacturing Bearings (Machinery) -- Design and construction Automated guided vehicle systems UCTD Thesis (MEng)--Stellenbosch University, 2024. ENGLISH ABSTRACT: The rolling element bearings market is mature, with a massive range of products available and new ones being developed continuously due to technological advances. Developing self-lubricating bearings using additive manufacturing techniques presents an exciting advancement in this industry, specifically for automated guided vehicles in e-commerce warehouse applications. It is speculated that South Africa’s online retail industry will break the R100 billion retail sales mark by 2026. As a result, one of South Africa’s biggest online retailers, Takealot, has started integrating automated guided vehicles into its operations. In April 2022, Takealot opened a new Cape Town warehouse equipped with state-of-the-art distribution centre technology. Notably, the Weasel automated guided vehicles boosted productivity by ensuring a fully automated collection process, with an average collection time of just 3 minutes. It was important to focus on developing self-lubricating bearings with a reduced wear rate because even though it is cheap to replace a worn-out bearing, it is the loss in productivity and reduction in operational efficiency that are more costly to a company when a bearing fails to meet its expected life. This study focused on using selective laser melting technology to develop rolling element bearings with a reduced wear rate and coefficient of friction. These rolling element bearings could ultimately improve operational efficiency and reduce the maintenance costs of automated guided vehicles by addressing the limitations of conventional rolling element bearings, such as the need for regular lubrication and susceptibility to wear and tear. The study involved printing porous 304 stainless steel samples by selective laser melting. The targeted porosity range for this exercise was between 15% and 35%, as is typical for self-lubricating bearings produced by conventional powder metallurgy processes. The parameter values of scanning speed, laser power and hatch spacing that obtained porosity values within the targeted range were then used to print samples for compression as well as friction and wear testing after they had been determined to have connected porosity by impregnation. Friction and wear tests were conducted on the porous samples, with a fully dense sample used as a control. The results demonstrated that SLM can fabricate porous samples with connected porosity, facilitating their impregnation. The tested samples also exhibited the capability to sustain the compressive loads sustained in the intended area of application, as well as superior wear and friction performance. The lowest recorded coefficient of friction was 0.041, corresponding to the lowest tested porosity of 16.8%. The highest recorded coefficient of friction was 0.100. These values were significantly lower than the coefficient of friction for the dense sample, which was 0.650. These findings suggest that selective laser melting can produce high-performance bearings, and its successful implementation could lead to significant cost savings and productivity improvements in automated guided vehicles. AFRIKAANSE OPSOMMING: Die mark vir rol-elementlaers is volwasse, met ʼn baie groot verskeidenheid produkte wat beskikbaar is en nuwes wat deurlopend as gevolg van tegnologiese vordering ontwikkel word. Die ontwikkeling van selfsmeerlaers met behulp van additiewe vervaardigingstegnieke is ʼn opwindende vooruitgang in bedryfingenieurswese, in die besonder vir geoutomatiseerde geleide voertuie (GGV’s) in e-handelpakhuistoepassings. Daar word gespekuleer dat Suid-Afrika se aanlyn kleinhandelbedryf teen 2026 die kleinhandelverkopeperk van R100 biljoen sal verbysteek. Derhalwe het een van Suid-Afrika se grootste aanlyn kleinhandelaars, Takealot, begin om geoutomatiseerde geleide voertuie by sy bedrywighede te integreer. In April 2022 het Takealot ʼn nuwe pakhuis, wat met die jongste distribusiesentrumtegnologie toegerus is, in Kaapstad oopgemaak. Die Weasel geoutomatiseerde geleide voertuie het produktiwiteit ʼn hupstoot gegee deur ʼn ten volle geoutomatiseerde insamelingsproses, met ʼn gemiddelde insamelingstyd van slegs drie minute, te verseker. Dit was belangrik om op die ontwikkeling van selfsmeerlaers met ʼn verlaagde slyttempo te fokus, want hoewel dit goedkoop is om ʼn uitgediende laer te vervang, kos die verlies aan produktiwiteit en die vermindering in bedryfsdoeltreffendheid die maatskappy baie meer as ʼn laer nie so lank soos sy verwagte lewensduur hou nie. Hierdie navorsing het gefokus op die gebruik van selektiewe lasersmelttegnologie om rol-elementlaers met ʼn verlaagde slyttempo en wrywingskoëffisiënt te ontwikkel. Hierdie rol-elementlaers kan uiteindelik bedryfsdoeltreffendheid verbeter en die instandhoudingskoste van geoutomatiseerde geleide voertuie verminder deur die beperkings van konvensionele rol-elementlaers, soos die behoefte aan gereelde smering en kwesbaarheid vir slytasie, aan te pak. Die studie het die druk van poreuse 304 vlekvrye staal monsters deur selektiewe lasersmelting behels. Die teiken- poreusheidsomvang vir hierdie oefening was tussen 15% en 35%, soos in selfsmeerlaers wat deur vonkplasma-sintering vervaardig word, waargeneem kan word. Die parameterwaardes van die skandeerspoed, laserkrag en luikspasiëring wat poreusheidswaardes binne die geteikende omvang behaal het, is toe gebruik om monsters vir saamdruk-, wrywings- en slytasietoetsing te druk, nadat daar deur impregnering vasgestel is dat hulle oor gekoppelde poreusheid beskik. Wrywings- en slytasietoetse is op die poreuse monsters uitgevoer, met ʼn ten volle digte monster wat as kontrole gebruik is. Die resultate het aangetoon dat SLS poreuse monsters met gekoppelde poreusheid, wat die impregnering daarvan fasiliteer, kan vervaardig. Die toetsmonsters het die kapasiteit getoon om die druklaste wat in die beoogde toepassingsgebied gedra sal moet word, te dra, asook beter slytasie- en wrywingsprestasie. Die laagste aangetekende wrywingskoëffisiënt was 0.041, wat met die laagste getoetsde poreusheid van 16.8% ooreenstem. Die hoogste aangetekende wrywingskoëffisiënt was 0.100. Hierdie waardes was beduidend laer as die wrywingskoëffisiënt van die digte monster, wat 0.650 was. Hierdie bevindings dui daarop dat selektiewe lasersmelting hoëprestasielaers kan vervaardig en dat die geslaagde implementering daarvan tot beduidende kostebesparings en verbetering in produktiwiteit in geoutomatiseerde geleide voertuie kan lei. Masters 2025-03-31T13:24:39Z 2025-03-31T13:24:39Z 2024-12 Thesis https://scholar.sun.ac.za/handle/10019.1/131824 Stellenbosch University xviii, 157 pages application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Additive manufacturing Bearings (Machinery) -- Design and construction Automated guided vehicle systems UCTD Mashayamombe, Tafadzwa Development of additively manufactured self-lubricating rolling element bearings for warehouse-centric AGVs |
| title | Development of additively manufactured self-lubricating rolling element bearings for warehouse-centric AGVs |
| title_full | Development of additively manufactured self-lubricating rolling element bearings for warehouse-centric AGVs |
| title_fullStr | Development of additively manufactured self-lubricating rolling element bearings for warehouse-centric AGVs |
| title_full_unstemmed | Development of additively manufactured self-lubricating rolling element bearings for warehouse-centric AGVs |
| title_short | Development of additively manufactured self-lubricating rolling element bearings for warehouse-centric AGVs |
| title_sort | development of additively manufactured self lubricating rolling element bearings for warehouse centric agvs |
| topic | Additive manufacturing Bearings (Machinery) -- Design and construction Automated guided vehicle systems UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/131824 |
| work_keys_str_mv | AT mashayamombetafadzwa developmentofadditivelymanufacturedselflubricatingrollingelementbearingsforwarehousecentricagvs |