Department of Industrial Engineering - Research Articles

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    Selective laser melting: Evaluation of the effectiveness and reliability of multi-scale multiphysics simulation environments
    (Elsevier Ltd., 2024-01-31) Mukalay, Thierry Abedi; Trimble, John Alfred; Mpofu, Khumbulani; Muvunzi, Rumbidzai
    This study evaluates the effectiveness and reliability of Multi-scale Multiphysics Selective Laser Melting (SLM) Simulation Environments. A literature review and bibliometric analysis were conducted to identify the most widely used SLM Simulation Environments. The effectiveness of simulation environments was assessed through a SWOT analysis enhanced by an Analytic Network Process (ANP). The reliability of simulation environments was analysed through a design of experiment (DoE). The DoE solely assessed the ability of these environments to accurately predict part distortion. The results showed that the most robust SLM process simulation modelling systems are Ansys Additive Print, Comsol, Simufact Additive, Netfabb, and Simulia.
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    Conceptual optimal selection of an e-maintenance autonomous strategy in CNC machining: a case study
    (IEEE, 2024-07-11) Oyesola, Moses Oluwafemi; Mpofu, Khumbulani; Kanakana-Katumba, Grace
    This research aims to provide an effective valuable strategy for an effective maintenance management plan (MMP) with the specific needs and demands of a Computer Numerical Control (CNC) machine within a manufacturing plant setting. Given the critical role of the machine in the overall operational success of a factory, this study examines maintenance approaches that encompass autonomy by shifting from Total Productive Maintenance (TPM) involving corrective actions, and a run-to failure strategy. The primary focus of this research lies in the bands of historical data collection and analysis, highlighting three critical component-level failures of paramount importance for closely monitoring of the performance of the CNC machine. In the quest for an optimal maintenance strategy, the study assesses the viability of three distinct approaches: Preventive Maintenance, Predictive Maintenance, and E-Maintenance (Autonomous). To ensure the sustained health and efficiency of the case machine production line, the research employs Pugh's elimination matrix table as an evaluation tool.
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    Development of a conceptual framework for quality management system implementation in small and medium enterprises in South Africa.
    (IOS Press, 2023-07-27) Magodi, Aluwani Yvonne; Daniyan, Ilesanmi; Mpofu, Khumbulani
    Sustainability challenge remain a prevalent issue among the SMEs in South Africa. This implies that the survival of SMEs in South Africa after few years of existence is a challenge. In order to promote the sustainability and operational efficiency of SMEs in South Africa, this study aims to develop a conceptual framework for the implementation of Quality Management System (QMS). Relevant literature was reviewed to get an insight into the significance and challenges faced by the SMEs in South Africa. The literature also indicated the feasibility for process improvement, profitability and sustainability if the SMEs adopts the culture of QMS. This led to the development of a conceptual quality management framework for implementation in SMEs. The framework incorporates the basic quality management system requirements with a focus on process efficiency and sustainability. It is simple and could easily be implemented or modified by the SMEs.
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    Performance evaluation of a smart welding fixture and jig assembly.
    (Roman Science Publications, 2023-09-01) Sibanda, Palesa S.; Daniyan, Ilesanmi A.; Mpofu, Khumbulani; Sekano, Elvis P.; Seloane, Walter T.
    The increasing global competitiveness, dynamic customers’ and markets requirements as well as the bottom-line of profitability necessitate the use of smart welding fixture and jigs as work holding and locating devices during component parts manufacturing. This study presents the performance evaluation of a smart welding fixture and jig for welding operation. The smart welding fixture and jig assembly consists of a compressor, proximity sensors, thermostat, cooling system, clamping elements, fixture body support, cables as well as a control panel for pre-programming the conditions for the welding operation. The performance evaluation was carried out by comparing the pressure and the time taken for clamping and unclamping activities. The pressure selected for the evaluation ranges between 241 316.6 Pa - 792 897.4 Pa while measurement was taken in terms of the time it took the edges-gripping clamps to return to their initial states. The results obtained also show that at as the pressure increase, there was a decrease in the time taken for the clamping and unclamping activities up to 379 211.8 Pa. Further increase in the pressure beyond 379 211.8 Pa first resulted in an increase in the time taken up to 792 897.4 Pa. When the pressure was increased beyond 792 897.4 Pa, it was observed that the time taken for the clamping and unclamping activities begin to increase and later reduces. The machine demonstrated the potential for saving 32.26% of the total time during the manual operation when the machine is operated in an automatic mode. This study provides empirical findings that can assist manufacturing industries particularly those who employ welding as a means of product fabrication in achieving welding operations in a timely and cost-effective manner with less human intervention.
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    System dynamics modelling and simulation of computer control systems for steel ingot furnaces.
    (South African Journal of Industrial Engineering, 2023-12-14) Somo, Gabriel; Daniyan, Ilesanmi Afolabe; Swanepoel, Jan; Mpofu, Khumbulani
    The problem that necessitated this study was that some furnaces that were responsible for the further processing of steel pipes at Company X were not connected to a programmable logic control (PLC)–Internet of Things (IoT) system. This slowed down the product flow. To address this problem, PLC-IoT systems were integrated so that the production system could be more effective. This study therefore models and simulates the integrated PLC-IoT control system, using the system dynamics modelling approach to investigate the performance of the automated gas furnaces. The PLC-IoT consists of an internal module that is used to process the data stream. After the implementation of the proposed control system, primary data was acquired by continuously evaluating the performance of the system. The research methodology used involved quantitative analysis and a simulation model using the Anylogic software. The result of the delivery and inventory of ingots from an automated system showed an upward trend with delivery and an inventory of an ingot at about 90 minutes; while a system that was not automated with PLC-IoT showed a downward trend of ingots. This shows that the introduction of the PLC-IoT for control makes the system more effective. The findings of this work could assist the manufacturers in achieving manufacturing or production efficiency, significant time savings, and better monitoring of the manufacturing process.
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    Optimising a processing window for the production of aluminium silicon-12 samples via selective laser melting.
    (Elsevier B.V., 2023-12-07) Nzengue, Alliance Gracia Bibili; Mpofu, Khumbulani; Mathe, Ntombizodwa Ruth; Muvunzi, Rumbidzai
    Selective laser melting (SLM) SLM has gained interest in processing lightweight metals like aluminium alloys. The SLM processing remains challenging in finding the appropriate process parameters for the desired mechanical properties. Previous studies have used energy density formulas and heat treatment to improve the mechanical properties of materials in different ways. However, the holistic approach to studying the physical and mechanical properties has less been reported. Therefore, this article presents the optimisation of the processing window of the AlSi12 aluminium alloy produced by the SLM process. The design of the experiment (DoE) was carried out using the Response Surface Methodology (RSM) implemented in the Design Expert 2018 environment. It involved two process factors in the following range of scan speed (500–2500 mm/s) and laser power (50–300 W). The combination of a scan speed of 500 mm/s and a laser power of 300 W resulted in a relative density of 97.4 %, an ultimate tensile strength (UTS) of 418 MPa and a hardness of 132.6 HV. The microstructure and fracture analysis provided evidence of reduced defects with the combination of parameters mentioned above. Thus, this study contributes to adding a new set of data to existing work for more comprehensive parameter calibration. This study helps industries that produce aluminium alloys from SLM processes obtain the optimal range of process parameters that produce parts with the desired mechanical properties.