IN-SITU ALLOYING PROCESS OF TI6AL4V-xCU STRUCTURES BY DIRECT METAL LASER SINTERING

Published Conference ProceedingsIn this paper the fabrication of in-situ Ti6Al4V-xCu alloy structures by DMLS are investigated. Ti6Al4V is a commonly used biomedical alloy because of it suitable mechanical and biocompatible properties. Copper is a proven anti-bacterial agent and in small amounts is not toxic to the human body. Ti6Al4V-xCu implants can be constructed to have a biocompatible structure with copper additions to reduce the risk of bacterial infection and implant failure. Infection at the bone–implant interface is the most probable reason for implant failure directly after implantation. Ti6Al4V powder was mixed with Cu powder to form a master alloy. Optimal process parameters need to be established for in-situ alloying of Ti6Al4V-xCu to form dense parts with suitable surface quality. The effect of laser scanning speeds and hatch distance on surface characteristics was investigated. The surface roughness, chemical composition and distribution of Cu near the surface and within the synthesized layer, as well as micro hardness were considered. A rescanning strategy was employed and showed improved alloy homogeneity and surface quality

Assessment of the mediating effects of external integration on manufactury firms operational performance

Purpose: The purpose of this study was to assess both the direct effect of supply chain integration on firm’s operational performance and the mediating effect of external integration (customer integration and supplier integration) on the relationship between internal integration and operational performance among manufacturing firms. Design/methodology/approach: Quantitative survey research design was adopted. A total of thirty (30) manufacturing firms were sampled using cluster sampling. The data was collected using questionnaires from 317 employees in the procurement, account and administration units of the 30 manufacturing firms. Structural Equation Modeling was used to analyze the direct and mediation relationships. Findings: The results showed that the relationship between internal integration and operational performance was significantly mediated by external integration. It was established that operational performance could only be achieved when manufacturing firms’ managers pay critical attention to internal and external integration. A Significant positive relationship also exists between supplier integration and operational performance as well as customer integration and operational performance. Originality/value: The unique contribution of the current study is the assessment of the mediating effect of external integration constructs (customer integration and supplier integration) as the mediating variable on internal integration and operational performance

Green Supply Chain Management and Environmental Performance: The moderating role of Firm Size

This study examined the impact of internal and external green supply chain practices on environmental performance among construction firms. The study used the quantitative survey research design in its methodology. A total of 217 employees were sampled from fifty (50) construction firms. Structural Equation Modeling was used to analyze the data. The results showed that green design does not have a significant positive relationship with environmental performance. However, green design has a positive impact on external green practices namely green purchasing and green construction. Green purchasing and green construction have direct positive relationships with environmental performance. Green design through external green practices have a significant positive relationship with environmental performance. The study found that firm size moderates the relationship between green design, through external green supply chain practices and environmental performance among construction firms

Manufacturing, microstructure and mechanical properties of selective laser melted Ti6Al4V-Cu

Conference ProceedingsTi6Al4V is a commonly used biomedical alloy because of its suitable mechanical and biocompatible properties. Infection at the bone–implant interface is the most probable reason for implant failure directly after implantation. Copper is a proven anti-bacterial agent and in small amounts is not toxic to the human body. Copper additions reduce the risk of bacterial infection and implant failure. Thus advanced implants can be constructed to have a biocompatibility and antibacterial properties. Optimal process parameters are needed to be established for in-situ alloying of Ti6Al4V-Cu to form dense parts with suitable mechanical properties. The effect of laser scanning speeds and hatch distance on morphology of single layers was investigated. The surface roughness, chemical composition and distribution of Cu near the surface and within the synthesized layer, as well as micro hardness were considered. An employed rescanning strategy showed improved alloy homogeneity and surface quality. On the base of these data 3D samples were produced. Microstructure and mechanical properties of as-built parts were analysed

Supply chain integration and operational performance in health institutions: A structural model for mediation effects

This study has examined the impact of supply chain integration on operational performance among health institutions. The study assessed the direct, indirect and mediated effects of supply chain integration on operational performance among health institutions in Ghana using the Structural Equation Modelling (SEM). In this research, the quantitative descriptive survey research design was used. A total of twenty (20) health institutions were sampled from an accessible population of thirty (30) using the simple random sampling technique. A total of two hundred and fifty-four (254) employees and managers from the health institutions were sampled using the stratified sampling technique. For direct effects, the findings of the study have shown that internal integration positively impacts external integration (customer and supplier integration). Direct positive relationships exist between internal integration and operational performance as well as supplier integration and operational performance. A non-significant relationship exists between customer integration and operational performance. For mediation effects, supplier integration significantly mediates the relationship between internal integration and operational performance, while customer integration does not significantly mediate the relationship between internal integration and operational performance among the health institutions in Ghana. The study has managerial implications for health institutions in strengthening their supplier and customer integrations through advanced database systems to enhance their operational performance

Additive manufacturing towards product production: A bibliometric analysis

Additively manufactured products offer extensive variety to consumers than many forms of production. Additive manufacturing (AM) production system allows consumer involvement, which has created a huge but largely untapped market. However, there is a gap between production and the market. Therefore, AM towards product production which focuses on the Commercialization of Additive Manufactured Products (CAMPs) is imperative. Despite the importance of CAMP, specific focus of research on the commercialization of additively manufactured products are scanty. There is also a lack of knowledge about the conceptual structure, intellectual structure, research trends, and the thematic structure of CAMP research. To contribute to this stream of research, this study takes an exploratory dimension by conducting a bibliometric analysis of publications on the CAMP. The R package and its associated biblioshiny were the software used. The study reveals that studies on CAMP started in 2007 with renewed interest starting from 2012. Importantly, it was found that the most cited articles focused on the economic potential of AM products in the home and specific industries. Also, there is an increasing focus on the business models that are necessary for the commercialisation of AM products. Generally, there is a shift in focus from the firm to the market. However, this is a niche area and requires more attention. Themes such as commercialization are just emerging, and researchers need to devote more time and effort to the consumer side of the commercialization of AM products

Additive manufacturing interventions during the covid-19 pandemic: South Africa

Additive manufacturing (AM), also known as 3D printing, is considered a renaissance of the manufacturing industry. Its unique capability of manufacturing 3D objects with intricate geometrical configurations has been used to produce hospital equipment and personal protective equipment (PPE) in an attempt to curb the spread of the COVID-19 pandemic in South Africa. The technology has been used by different research units to produce ventilators, respirator face masks, oscillating respiratory devices, oxygen connectors, oxygen splitters, non-invasive ventilation helmets, reusable clinician PPE, visor frames for face shields, etc. Despite the efforts of the AM community in South Africa, COVID-19 infections have continued to increase in the country. It came to light that technological interventions (including AM) alone cannot prevent the spread of the virus without the corresponding adaptive behavioural changes, such as adhering to COVID-19 prevention protocols (washing of hands, social distancing, etc.). It could be postulated that the spread of COVID-19 can only be prevented by inter-marrying the technological interventions (AM) with adaptive behavioural changes

Additive manufacturing in South Africa: critical success factors

Despite the advances and significant benefits of additive manufacturing globally, Africa and several developing countries are lagging behind due to several adoption barriers. South Africa has nevertheless made significant gains in the area of additive manufacturing over the past three decades. The current study examines the critical success factors that have led to South Africa's relative success in the field of additive manufacturing by overcoming the barriers. One of such success factors was the demonstration of visionary leadership and commitment to additive manufacturing through huge investments. The building of human capital through education and research in the area of additive manufacturing is another factor. The development of a strong collaboration between industry and research involving both local and international institutions represents another success factor in South Africa's additive manufacturing growth. Lastly, a positive national culture that drives the adoption of new technologies which is defined by the display of low power distance, high individuality, masculinity, and lower uncertainty avoidance index is another success factor of additive manufacturing in South Africa