G.A. Oosthuizen

G.A. Oosthuizen
Stellenbosch University | SUN · Department of Industrial Engineering

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90
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Introduction
Skills and Expertise

Publications

Publications (90)
Article
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Shared value creation at the Base of the Pyramid (BoP) receives growing interest. The BoP is a socio-economic group characterised by people who have poor nutrition, limited income, inadequate technologies, lack of access to markets and poor infrastructure to produce valuable products and services. Possible methodologies and systems to successfully...
Article
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This paper investigates the behavior of titanium formability when forming under localized friction heating, caused by high tool rotation. In accordance with planned experiments, different process conditions at various tool rotations, feed rates, and step-down sizes were investigated. The experiments were carried out on 1 mm thick Ti6Al4V alloy shee...
Article
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Machining is an integral shaping process for most titanium alloys based components. However, the ease of machining (machinability) of Titanium and its alloys is generally poor because the alloys have low thermal conductivity, high strength at high temperatures, which both combine to speed up the tool deformation and wear. The poor machinability of...
Article
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South Africa has significant titanium reserves and is developing strategies to not only provide this raw material on global markets, but to manufacture complex titanium alloy products and participate fully in global supply chains. Pursuing more sustainable process chains, manufacturers are constantly striving to enhance the resource efficiency of t...
Article
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The effects of tool rotation direction during single point incremental forming of pure titanium were experimentally studied. Axisymmetric components with a varying wall angle were formed using a round-tipped tool of 10 mm diameter and following a 3D spiral tool path. Test runs were executed by changing one factor at a time. Spindle rotation was tes...
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Driven by the rising demand for individualized high-tech products the machine building industry continuously introduces a wide variety of smart innovations. Manufacturing companies face growing production requirements which can only be only handled by intelligent systems. During the last decades the trend in manufacturing has shifted from the class...
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In order for suppliers to stay competitive in the global market, innovative and resource efficient process chains need to be a part of their manufacturing strategies. In this study the effect of different waste to resource process chain strategies were evaluated. The objective was to transform the material waste from a cutting process into a resour...
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The manufacturing challenges industry face need to be addressed in the multifaceted context of sustainability. In order to stay relevant and competitive the manufacturing industry is investigating several types of sustainable hybrid materials for structural components. Bamboo is a versatile plant with thousands of applications, but is produced in v...
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The next generation of manufacturing will be focused of utilizing lean tools within production industries. Internet of Things (IoT) has made its progress evolvement into the manufacturing industry and has led to improved control when implemented to monitor manufacturing resources. Smart production systems can integrate the virtual and physical worl...
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The use of Titanium alloys is becoming more widespread in the aerospace, automotive and medical industries due to its favourable mechanical and thermal characteristics. Reducing the number of defective parts will increase the overall efficiency of the machining operation and thereby contribute to a more sustainable manufacturing process. An industr...
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The next generation of manufacturing systems will be self-organising. Networking of cyber-physical equipment and machinery are on the rise. In the field of sustainable manufacturing, an increasing level of computerisation is used to face the growing production requirements. Smart production systems will foster opportunities from its artificial inte...
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Pursuing more sustainable process chains, manufacturers are constantly striving to enhance the resource efficiency of their manufacturing processes. As part of this, additive technologies have become increasingly important for reducing waste, time and costs. Various input factors affect the efficiency of an additive approach and therefore also have...
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In order for manufacturing suppliers to stay competitive in the global market, innovative and resource efficient process chains need to be a part of the manufacturing strategy. Primary manufacturing process steps entail the shaping, moulding, milling and forming processes applied to the raw materials to add value to the product. Bicycles have an en...
Article
Full-text available
In order for manufacturing suppliers to stay competitive in the global market, innovative and resource efficient process chains need to be a part of the manufacturing strategy. Secondary manufacturing process steps entail the assembly and surface treatment manufacturing steps after the primary cutting and shaping of the components. Bicycles have an...
Article
Full-text available
The use of additive manufacturing to produce intricate part geometries in the aerospace, medical, and tool-and-die industries is increasingly incorporated in manufacturing process chains. However, the high costs, long production times, and material integrity issues associated with additive manufacturing technologies such as selective laser melting...
Conference Paper
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Electricity infrastructure resilience of the South African power grid is challenging, considering the lack of generation support from our neighbouring countries in the event of a blackout incident [1]. A blackout incident is a very low-probability, high impact incident and, in the context of this paper, refers to an event that results in the total...
Article
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The main challenges in high performance milling of difficult-to-machine metals are embedded in the development of innovative machining methods and cutting strategies. The aim is to reduce cycle time, resources and cost while maintaining or enhancing the machined product’s quality and performance. This will assist to increase both productivity and p...
Article
Purpose The purpose of this paper is to investigate the combination of selective laser melting (SLM) and 5-axis CNC milling to produce parts from titanium powder. The aim is to achieve a more resource-efficient manufacturing process by reducing material wastage and machining time, while adhering to quality requirements. Design/methodology/approach...
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The demand for titanium is continuously growing with the increased use of its alloys in new generation aircrafts. It is classified as a difficult-to-machine metal and therefore large costs are associated with the removal of material during machining operations. Working towards more resource efficient process chains, the aim is to reduce cycle time...
Article
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Near net-shape technologies are increasingly used to enhance resource efficiency in high performance machining for various applications, including aerospace. In this paper the effect of a pre-formed based manufacturing route on the residual stress state of an aerospace part in Ti6Al4V is presented. The manufacturing strategies, including the pre-fo...
Article
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This paper deals with a study focused on the single point incremental forming (SPIF) of titanium Grade 2 sheets. The direct impact of the sliding velocity of the forming tool on mechanical and thermal process loads was experimentally investigated. A wide range of spindle speeds and feed rates were examined at different forming conditions. The devel...
Article
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Dovetail joints are one of the strongest joining methods used to connect two perpendicular components together. Dovetail joints are predominantly used in wooden components but can also be found in other non-wood components and products such as lathes, turbine blades, clock gears, and large 3D printed components. The manufacturing of these joints ha...
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Automation of processes is becoming increasingly popular within manufacturing. However, in third world countries such as South Africa, automation could lead to the loss of jobs and even higher unemployment. In order to remain globally and locally competitive, companies need to invest in new technologies of which automation is a highly influential a...
Article
Full-text available
In order for manufacturing suppliers to stay competitive in the global market, innovative and resource efficient process chains need to be a part of the manufacturing strategy. Secondary manufacturing process steps entail the assembly and surface treatment manufacturing steps, after the primary cutting and shaping of the components. Bicycles have a...
Conference Paper
Full-text available
The success of 3D printed prosthetics over the last few years has made way for further research and development within the field to improve the functionality and aesthetics of low-cost prosthetics. An opportunity now exists to develop a product, similar to that of Robohand and eNable , but which uses myoelectric control rather than mechanical contr...
Conference Paper
Full-text available
Near net-shape technologies are increasingly used to enhance resource efficiency in high performance machining for various applications including aerospace. In this paper the effect of a pre-formed based manufacturing route on the residual stress state of an aerospace part in Ti6Al4V is presented. The manufacturing strategies, including the pre-for...
Article
Full-text available
The high cost of quality prostheses, together with the lack of trained prosthetists, makes it challenging to obtain prosthetic devices in developing communities. Modern 3D digitising techniques and additive manufacturing (AM) technologies are gaining popularity in the bio-medical industry and, in the case of prosthesis production, reduce the need f...
Conference Paper
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Cemented carbide tools, specifically tungsten carbide based alloys, have found a wide range of application fields including manufacturing, agriculture, and mining, among others. A need for customised tooling solutions using cemented carbide alloys have been identified. Additive manufacturing is chosen as a novel manufacturing process due to its sup...
Article
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Sustainable manufacturing pursues various approaches, one of them is value creation through social innovations from open source innovations, respectively open design strategies. Well-known names such as “Local Motors” are a prime example for its success. But there are also concepts, which limit the sustainability of this success and can, consequent...
Conference Paper
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The utilisation of Additive Manufacturing (AM) for the production of intricate parts in the aerospace, medical, and tool-and-die industries is continuously receiving more interest. In the tool-and-die industry AM has been successfully used to integrate complex cooling channels inside injection and blow moulds. This results in a significant increase...
Article
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Postoperative infections are a major concern in patients that receive implants. These infections generally occur in areas with poor blood flow and pathogens do not always respond to antibiotic treatment. With the latest developments in nanotechnology, the incorporation of antibiotics into prosthetic implants may soon become a standard procedure. Th...
Article
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BACKGROUND: Infections are common in intensive care units (ICUs) and burns units. Empiric antibiotic therapy is often required, and as such it is important to have a good knowledge of the resident organisms in these departments. Antibiotic resistance is becoming an increasing problem both internationally and in South Africa (SA) and it is important...
Conference Paper
This paper presents initial work and prototyping of an Ironless Double-Rotor Radial Flux Permanent Magnet (IDRFPM) machine. The design stems from high-efficiency generators intended for wind power but will be used in motor operation to propel a small vehicle for the Shell Eco Marathon where efficiency is of paramount importance. The design intends...
Article
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Bacterial colonisation and biofilm formation onto orthopaedic devices are difficult to eradicate. In most cases infection is treated by surgical removal of the implant and cleaning of the infected area, followed by extensive treatment with broad-spectrum antibiotics. Such treatment causes great discomfort, is expensive, and is not always successful...
Article
The use of electric machinery is often restricted or complicated in weight-sensitive applications such as light vehicle propulsion due to the amount of heavy ferromagnetic materials generally required. An existing Double-Rotor, Radial Flux, Air-cored Permanent Magnet (D-RFAPM) design was altered by adding inter-pole azimuthally oriented magnets to...
Conference Paper
The use of electric machinery is often restricted or complicated in weight-sensitive applications such as light vehicle propulsion due to the amount of heavy ferromagnetic materials generally required. An existing Double-Rotor, Radial Flux, Air-cored Permanent Magnet (D-RFAPM) design was altered by adding inter-pole azimuthally oriented magnets to...
Article
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Machining induced residual stresses may have a significant effect on the mechanical performance of machined parts. AdvantEdge is an advanced finite element code dedicated to the modelling of the machining process. This paper describes a comparative evaluation of modelling results obtained with AdvantEdge with experimental results obtained during tu...
Conference Paper
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Residual stress is an important surface integrity descriptor that may have a marked effect on the functional performance of titanium alloy parts. This paper describes a numeric evaluation of the machining induced residual stresses in Ti6Al4V (Grade 5) titanium alloy. A two dimensional orthogonal turning process was modelled and the results compared...
Conference Paper
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A project-based approach to educate mechatronics at the University of Ljubljana is presented. It combines the classical curriculum composed of various engineering subjects with project-based work. The emphasis is on ‘learning-by-doing’ with concrete projects. Doing this student teams design systems and manufacture mechatronic prototypes. Recently,...
Conference Paper
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The production of prostheses using conventional methods or advanced technologies makes it unaffordable for people living in developing communities. Since the Fablab revolution and due to the collaborative open source movement, numerous rapid product development technologies were invented. The idea of these movements is to provide widespread access...
Article
PURPOSE: To develop a new schematic scheme for efficiently recording the key parameters of gas permeable contact lens (GP) fits based on current consensus. METHODS: Over 100 established GP fitters and educators met to discuss the parameters proposed in educational material for evaluating GP fit and concluded on the key parameters that should be rec...
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p>ENGLISH ABSTRACT: Ti6Al4V is one of the most widely used titanium alloys in aerospace applications, but its machining remains a challenge. Comprehensive research has been done in the past, mainly investigating tool failure of various materials. Less research has been done to investigate the thermal effect of machining on work piece quality, inclu...
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p>ENGLISH ABSTRACT: Energy use will be one of the main drivers for the achievement of more eco-efficient drilling processes in the automotive industry. Industry awareness of the environmental impact of used cutting emulsions, and the negative effect on worker health, has increased sharply. This has led to innovative lubrication methods such as thro...
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p>Most studies concur that climate change could seriously affect the sustainability and well-being of developing countries as they depend directly on climate-sensitive natural resources for their livelihood endeavours. This could primarily occur through reduced agricultural productivity, a higher incidence of diseases, the displacement of people, l...
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This paper comprises an investigation using finite element analysis to study the behaviour of nanocrystalline grain structures during Equal Channel Angular Press (ECAP) processing of metals. The effects of average grain size and misorientation angle on the deformation are examined in order to see how microstructural features might explain the obser...
Article
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Tool performance of conventional tools is poor and a major constraint when used in milling titanium alloys at elevated cutting speeds. At these high cutting speeds, the chemical and mechanical properties of Ti6Al4V cause complex wear mechanisms. In this paper, a fine-grain polycrystalline diamond (PCD) end mill tool was tested, and its wear behavio...
Article
South Africa is facing severe poverty levels especially in underdeveloped rural regions. Manufacturing is seen as the sector which could create jobs, but it requires an innovative development concept. The concept of sustainable manufacturing networks is proposed. It is based on the principles of social networks, network manufacturing and open sourc...
Article
This paper presents an investigation of different PCD tool grades in a High Speed Machining (HSM) process for the finish milling of Ti6Al4V. Different lubrication strategies for PCD were evaluated and compared to coated carbide under flood lubrication. The performances of the most suitable PCD grade have been investigated in terms of tool life, chi...
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This paper proposes the application of precision pallet technology, together with common 3-axis milling, to machine certain complex aerospace components that are normally 5-axis machined. In this approach a set of different customised precision pallets are used to present each complex plane to the 3-axis machine as a series of horizontal planes for...
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1. Background Parking is an important and integral part of the transportation system in a metropolitan area. The provision of parking is expensive. The parking rates required for parking at developments should be sufficient, but care should also be taken not to provide too much parking. Insufficient parking, on the other hand, can result in overflo...
Article
To evaluate the nutritional status of HIV-1 seropositive patients with regards to laboratory parameters; the correlation between nutrient intake and actual values of nutrients, as well as the relationship between malnutrition and disease progression. A cross sectional study. The Immunology Clinic at the Pelonomi Hospital in Bloemfontein, South Afri...
Article
. The use of a so-called concept lattice for deriving concepts from a given set of entities and attributes is examined. A number of variations are discussed including constrained, unconstrained and augmented concept lattices. Bounds for worst case behaviour, as well as conditions under which worst-case behaviour arises, are adduced. It is argued th...
Article
The rapid pace at which data gathering, storage and distribution technologies are developing is outpacing our advances in techniques for helping humans to analyse, understand, and digest the vast amounts of resulting data. This has led to the birth of knowledge discovery in databases (KDD) and data mining—a process that has the goal to selectively...
Article
Complex and large systems can be hard to manage if the elements that they comprise have dynamic causal relationships. Management of such a system usually entails monitoring and interpreting data generated by various elements of the systems. This data needs to be processed into meaningful information, so that a manager can use the information to get...
Article
The spontaneous and rapid growth of indigenous African Christianity, especially in South Africa, has undermined the appropriateness of the term "mainline" for the traditional, denominational churches in the area. Some of these churches lost more than twenty-five percent of their membership in the period 1980-1990, while membership of the indigenous...
Conference Paper
Recently, there has been much interest in connectionist learning as alternative to symbolic learning methods. The purpose of the paper is two fold: 1) it considers briefly the fundamental differences between the symbolic and connectionist approaches to learning by relating them to a common mathematical framework; and 2) a model which can be categor...
Chapter
This paper addresses the problem of visualizing data of dimension higher than three. The method described is primarily aimed at so-called categorical (or nominal) data, but also applies to other discrete-valued data, i.e. data entities defined in terms of vectors of discrete attribute values. Categorical data is data with unordered attribute values...
Conference Paper
A Concept lattice is a special kind of lattice, the explicit representation of which can be viewed as a semantic network with special properties. Concept lattices have been applied to Machine Learning as well as to the uncovering of the underlying structure in discrete-valued data. They also embody the cladistic approach to classification. This pap...
Chapter
Theological and church discussions of the vital questions of race relations in South Africa have often been far removed from the actual situation in which people experience the consequences of state and church decisions, many of which deeply affect their lives. By contrast, a scientific approach to religions should study people’s actual situations,...
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Evaluation criteria for selecting an organisation in the engineering profession. This study deals with identifying the evaluation criteria according to which people in the engineering profession choose the organisation where they will work. The research group consisted of 211 final-year engineering students, and 256 engineers employed by a specific...
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The motivation of the Black worker can not be studied in isolation since the White worker still holds many executive positions and therefore has an influence on the Black workers' motivation. The role of the White worker in motivating the Black worker in a specific organisation and the attitude and leadership approach of the White worker on the exi...
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In die geledere van skokkende en onetiese dade in die menslike samelewing, beklee aborsie ’n besondere plek. Vir wetenskaplike doeleindes kan aborsie oor die algemeen gedefinieer word as die skeiding van of afdrywing uit die moederlyf van die „produk” van konsepsie, synde ’n fetus (Geldenhuys, 1974:11; O’Donovan 1975:2). ’n Verdere element van die...
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After the merger between the University of South Africa, Technikon South Africa and the distance education campus of Vista University, the College of Economic and Management Sciences at the University of South Africa initiated a research project to determine whether the college complies with the quality criteria set for higher education in general,...
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Thesis (D. Comm.)--Rand Afrikaans University, 2002. Includes bibliographical references (leaves 213-222).
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The titanium alloys have found wide application in the aerospace, biomedical and automotive industries. Soaring fuel prices and environmental concerns are the fundamental drivers that intensify the demand situation for titanium. From a machining viewpoint, one of the challenges companies face, is achieving high material removal rates while maintain...
Article
ENGLISH ABSTRACT: Information on the milling of Ti6Al4V is limited; with most studies concluding that it is not possible to obtain a significant increase in the material removal rate (Qw). Tool wear maps can be a diagnostic instrument for failure analysis. Cutting speed (vc), maximum un-deformed chip thickness (heMax) and the radial immersion perce...
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