SUNScholar - Browsing by Author "Oosthuizen, G. A."

Browsing by Author "Oosthuizen, G. A."

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Characteristics of single layer selective laser melted tool grade cemented tungsten carbide
(Stellenbosch University. Faculty of Engineering. Dept. of Industrial Engineering., 2016) Van Staden, A. C.; Hagedorn-Hansen, D.; Oosthuizen, G. A.; Sacks, N.
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 superior material and process flexibility. The study investigates the melting behaviour observable during the SLM process using a tool grade cemented tungsten carbide powder. The laser power, scan velocity, and hatch spacing of the SLM process are varied and single powder layers are sintered accordingly. This is done to determine the varying influence these parameter combinations have on the melting behaviour of the material during sintering. For each set of parameter combinations the test samples were analysed using microscopic imaging. It is found that a combination of high laser power, high hatch spacing, and low scan speed yields the best results.
A conceptual framework to create shared value in base of the pyramid communities with micro-containerised factories
(Elsevier, 2019) Chihambakwea, Z. J .; Oosthuizen, G. A.; Matope, S.; Uheidaa, E. H.
ENGLISH ABSTRACT: 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 implement sustainable micro-containerised factories at the BoP are still very limited and remain unanswered. In this study a conceptual framework to create shared value in BoP communities with micro-containerised factories is developed. These factories provide portable, scalable technologies to produce valuable products from sustainable locally sourced resources or waste streams. Concepts from literature and case studies were evaluated to identify key elements for the conceptual framework. A proposed business model and conceptual framework were developed to guide business model prototyping in a case study in South Africa.
The development of experimental machines in order to understand the demands of incremental sheet forming of titanium
(Industrial Engineering, Stellenbosch University, 2011-09) Oosthuizen, G. A.; Nortje, H.; Herselman, E. J.; Akdogan, G.; Sacks, N.
Titanium sheet-metal is extensively used for aerospace and biomedical applications. The diversified customer's demands have created a recent trend towards the small batch production. In this context incremental forming has attained great attention. Therefore, experimental machines are designed and manufactured to simulate the harsh forming conditions. In the fretting machine the combination of a normal force and small vibrations may constitute a wear phenomenon known as fretting wear. The friction and wear properties of the tool, lubrication and work piece materials are tested using the sliding test machine. The steps to evaluate and develop these machines as research tools are illustrated and discussed. The fretting- and sliding machines help to investigate suitable forming tools, forming parameters and lubricant strategies for incremental forming of titanium. It is concluded that these simulation tools provide more efficient and cost effective ways to understand the effects of changing the forming conditions.
Developments in wear maps as machining optimisation tools
(Industrial Engineering, Stellenbosch University, 2011-09) Oosthuizen, G. A.
Tool wear maps can be a diagnostic instrument for failure analysis. This paper presents a summary of the recent developments of wear maps and experimental results from the milling of a Ti6Al4V benchmark component. This forms the foundation of understanding the cutting demands on the tools, in order to analyze the main wear mechanisms. Remedial actions are integrated via this understanding of the failure modes and related mechanisms. These maps present wear data in a graphical manner and are able to provide a more global picture of how materials behave during cutting. In tool wear maps there is a region where the rate of wear is at its lowest, called the safe zone. The presence of this safe zone suggests that it may be possible to select the machining parameters so that a machinist can operate with the lowest amount of tool wear, without compromising the level of productivity desired. Some thoughts on future directions for research in this area are also discussed.
The effects of selective laser melting scan strategies on deviation of hybrid parts
(Southern African Institute for Industrial Engineering, 2017-11-22) Hagedorn-Hansen, D.; Bezuidenhout, M. B.; Dimitrov, D. M.; Oosthuizen, G. A.
ENGLISH ABSTRACT: 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 make the process suitable only for certain applications. In order to reduce selective laser melting production costs for selected parts, a combination of selective laser melting and milling can be used. Metal parts produced with this method are referred to as hybrid parts. A challenge in producing hybrid parts is to reduce the geometrical deviation due to process-induced warping. This paper discusses the effects of various laser scan strategies on the deviation of hybrid parts. A newly developed scan strategy is experimentally compared with its commercial counterpart with regard to as-built part warping and porosity. The novel strategy resulted in a significant reduction in warping and porosity.
Emerging synthesis of social manufacturing
(Faculty of Engineering, Department of Industrial Engineering, Stellenbosch University, 2016) Steenkamp, L. P.; Ras, C. I; Oosthuizen, G. A.; Von Leipzig, K. H.
Manufacturing systems has changed constantly throughout the years and new theory towards value creation is emerging. The latest manufacturing paradigm is described as social manufacturing which uses open design platforms. Open design platforms could give the hands of every individual the means to produce physical objects or products. Nowadays, with the wave of the Internet of Things (IoT) people can participate from global communities to contribute to the innovation process. Everybody can use existing design tools and solutions on open platforms. This will ensure co-creation to produce even more solutions. Social manufacturing harnesses the emerging synthesis from open design platforms and the manufacturing capability that is embedded within the online community platform, whereby the users co-manufacturer their own products. This paper discusses an one week challenge case study that investigates the possibility of completing the open design process of a product during a limited timespan using social manufacturing techniques. This case study proved that a product can be crowd sourced and delivered within a week. These results showed that the desired industrial cluster could be reached. These social elements are promising for future manufacturing businesses.
Evaluation of communication systems for deep level mining monitoring applications
(Stellenbosch : Stellenbosch University, Department of Industrial Engineering, 2011-09) Van Wyk, P. J. J.; Oosthuizen, G. A.; Conradie, P. J. T.
Deep level mining companies face many problems affecting their development and profitability. One of these problems affecting growth is the lack of effective, yet economically viable, communication systems. This is especially necessary in rapidly expanding and changing environment mines. Resource companies need constantly growing revenues to remain competitive in the current mining industry. This paper identifies the constraints associated with applying communication systems in deep level mines, both the constraints affecting the physical machinery as well as constraints affecting the labourers installing, operating and maintaining the system. The existing communication systems are identified and then critically evaluated. The evaluation is done by identifying the advantages and disadvantages of each system, and by comparing the costs associated. The constraints play a prominent role in the evaluation phase as certain technologies immediately are discarded as possible selections when they clash with conflicting constraints. The results of the evaluation process are used to determine possible solutions with respect to communication problems faced in mining applications. Recommendations are made on the most efficient and cost effective technologies according to the results. These recommendations are used by mining companies to improve their current communication systems.
Evaluation of resource efficient process chains for secondary manufacturing processes of bamboo bicycles
(Elsevier, 2017) De Weta, P.; Oosthuizen, G. A.; Oberholzer, J. F.; Burgera, M. D.; Ras, C. I.
ENGLISH ABSTRACT: 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 enormous effect on society, both in terms of socio-economics and of advancing modern industrial processes. In order to manufacture bamboo bicycle frames in South Africa innovative designs and process chains need to be developed. In this study process chains for secondary manufacturing processes of bamboo bicycles were developed and compared. The manual secondary process steps for manufacturing bamboo bicycles in Africa were mapped and compared with developed technological process chains in terms of resource efficiency. The effect on time and cost were evaluated.
Evaluation of robot technologies for deep level mining applications
(Stellenbosch : Stellenbosch University, Department of Industrial Engineering, 2011-09) Louw, S. E.; Oosthuizen, G. A.; Al Shaalane, A.
Mining starts with the extraction of effortless resources, but quickly progresses to more complex situations. As the mining depth increase the technical challenges and difficulty to retrieve resources rises. The future deep-level mining environment is considered too immense a risk for human labour. Therefore, robot technology is considered as an alternative. This imposes the need to develop and improve current mining technology and equipment. This study evaluates robot technologies for deep level mining applications. Firstly, the constraints of robots associated in deep-level mining environments are identified. Thereafter, various existing robot technologies are analyzed to categorize functional attributes of each robot. These were assessed with regard to the constraints, establishing a basis for selection of a feasible robot technology platform. Recommendations are made on how to improve the existing robot technology to compensate for specific conditions. It is concluded that it is vital to improve existing robot technologies in order to mine at deeper levels. In collaboration with technology- and mining companies a mechanized mining concept was developed from these evaluations.
Evaluation of work piece temperature measurement techniques for milling of Ti6Al4V
(Stellenbosch : Stellenbosch University, Department of Industrial Engineering, 2011-09) Conradie, P. J. T.; Oosthuizen, G. A.; Treurnicht, N. F.; Al Shaalane, A.
Ti6Al4V is one of the most widely used titanium alloys in aerospace applications, but its machining remains a challenge. This is partly due to the lack of understanding of the thermal- and mechanical constraints during milling. Extensive research has been done in the past investigating catastrophic tool failure of various tool materials. However, not much research has been done to investigate the cause of work piece failure. The catastrophic effect of overheating the work piece and the resulting alpha case formation in titanium is well known. Current techniques of temperature measurement of the machined surface can be divided into two categories: contact- and optical methods. In this study these temperature measurement techniques were studied and evaluated. The response time of contact methods are found to be to relatively slow. The optical methods have the advantage of immediate response, allowing capture of intermittent heat generation as required in milling. The infrared camera temperature measurement experiments were conducted with a special setup in order to have a good visual of the temperature flow. The results of these experiments were found to correspond with literature.
Framework to develop and evaluate process chains for resource efficiency
(Faculty of Engineering, Department of Industrial Engineering, Stellenbosch University, 2016) Oettel, M. K.; Van Der Schyff, H.; Bezuidenhout, M. B.; Oosthuizen, G. A.
Continuous development of new, and the improvement of existing products yields a vast collection of concepts and prototypes. Such products do not yet necessarily have established process chains. An area therefore exists for the development of novel manufacturing process chains towards the production of such products. In order to select a process chain most suited to the user’s needs, it should be evaluated with regards to the design space in which it is applied. This paper presents a framework to create and evaluate resource efficient process chains, with an application example in the context of integrated medical implants. To realize this aim, a guideline was developed to lead the user through the entire thinking process for process chain evaluation. An empty template provides the user with creative freedom to apply the included methods for idea generation. After creating process chain variations, an assessment of each is executed. An evaluation score ranks the process chains in order of suitability for its specific purpose.
Innovative cutting materials for finish shoulder milling Ti-6A1-4V aero-engine alloys
(Stellenbosch : University of Stellenbosch, 2009-03) Oosthuizen, G. A.; Treurnicht, N. F.; University of Stellenbosch. Faculty of Engineering. Dept. of Industrial Engineering.
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 maintaining the form and function of the part. The ultimate aim for a machining business remains to make parts quickly. Conventional cutting speeds range from 30 to 100 m/min in the machining of Ti-6Al-4V. Milling this alloy faster however is challenging. Although titanium is becoming a material of choice, many of the same qualities that enhance titanium‟s appeal for most applications also contribute to its being one of the most difficult materials to machine. The author explored the potential for Polycrystalline diamond (PCD) inserts in high speed milling of Ti-6Al-4V, by trying to understand the fundamental causes of tool failure. The objective was to achieve an order of magnitude increase in tool life, while machining at high speed, simply by reducing some of the failure mechanisms through different cutting strategies. Tool wear is described as a thermo-mechanical high-cycle fatigue phenomenon. The capability of a higher material removal per tool life is achieved in the case of PCD inserts compared to Tungsten carbide (WC). The average surface roughness produced was relatively low. The collected chips were also analyzed. The work demonstrated progress over the performance reported in current literature. The work confirms that there is a region where a sufficiently high temperature in the cutting zone may contribute to extended tool life, provided that the tool material can withstand these extreme conditions.
Investigating current smart production innovations in the machine building industry on sustainability aspects
(Elsevier, 2018) Waibel, M. W.; Oosthuizen, G. A.; Du Toit, D. W.
ENGLISH ABSTRACT: 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 classic mass production to complex individualized products which have to be produced to compete with the costs of mass products. Smart Production Systems are characterized by its flexibility, resource efficiency, ergonomic design and the ability to integrate customer and business partner into the value creation process. This research study investigates current smart production innovations and trends in the machine building industry. The sustainability aspects and the potential of various smart innovations are outlined.
Investigating of eco- and energy-efficient lubrication strategies for the drilling of light metal alloys
(Southern African Institute for Industrial Engineerg, 2010) Treurnicht, N. F.; Joubert, H. J.; Oosthuizen, G. A.; Akdogan, G.
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 through-spindle minimal quantity lubrication (MQL) for drilling aluminium-silicon alloys. In this work the performance of MQL at different cutting speeds and feed rates has been investigated using infrared temperature measurements. The results indicate that MQL is a feasible eco-efficient alternative to conventional flood cooling when drilling aluminium-silicon alloys.
Investigating the effects of automating process chains towards sustainable manufacturing in South Africa
(Elsevier, 2017) Hagedorn-Hansen, D.; Steenkamp, L. P.; Hagedorn-Hansen, E.; Oosthuizen, G. A.
ENGLISH ABSTRACT: 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 aspect. Thus a study is deployed to determine when a company should automate a process and when a semi-automated process is sufficient in the process chain. To ensure a close to optimum operation, a balance between workforce skill development and profit needs to be determined. In this study, the effects of automating process chains were evaluated. A semi-automated process chain that included a manual labor aspect was used to manufacture small aluminium automotive components and was compared to an automated process with regards to machine effectiveness and labor resources. The automated process derived a higher profit margin due to the high availability of the machine and the lower labour costs. Suggestions were given to increase the profit margin without the loss of labour.
Investigating the effects of smart production systems on sustainability elements
(Elsevier, 2017) Waibel, M. W.; Steenkamp, L. P.; Moloko, N.; Oosthuizen, G. A.
ENGLISH ABSTRACT: 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 intelligence to create value within the business and the community it operates. Smart production systems will integrate the virtual and physical worlds on these Internet of Things (IoT) platforms to ensure flexibility and resource efficiency. This research study investigated the dynamics of the next industrial revolution (Industrie 4.0) and used case studies on the market, suppliers and customers as benchmark to identify current trends. The technical, economic, social and environmental elements of possible smart innovations were evaluated in terms of resource efficiency. Prerequisites for tooling companies to use smart production systems were discovered. Future work was also discussed.
Investigating the energy efficiency and surface integrity when machining titanium alloys
(Faculty of Engineering, Department of Industrial Engineering, Stellenbosch University, 2016) Tayisepi, N.; Laubscher, R. F.; Oosthuizen, G. A.
Sustainable manufacturing strategies will need to address the resource efficiency and surface quality challenges in cutting processes. This paper aims to provide a systematic methodology for modelling the input and outputs of a turning process to find the best balance between production rate and input cost, while improving or adhering to the quality standards. Ti6Al4V were cut under flood cooling using carbide cutting tools and a Taguchi design of experiments was used with ANOVA. Surface integrity and energy use were measured and analysed for selected cutting parameters. The experimental results highlighted the importance of selecting optimum cutting parameters and machining strategy. More energy was consumed at lower cutting parameters, whilst higher feed rates resulted in less energy consumption, but lower surface finish quality. These results will also assist to define the boundary conditions for various input parameters.
Investigating the feasibility to remove alpha case from titanium alloys with machining
(Faculty of Engineering, Department of Industrial Engineering, Stellenbosch University, 2016) Conradie, F. W.; Oosthuizen, G. A.; Sacks, N.
Titanium as an alloy offers excellent material properties including corrosion resistance, biocompatibility and high specific strength. These properties make titanium alloys highly desirable in demanding applications and specialised industries such as aerospace and orthopaedic prosthesis. However, the formation of a hard and brittle alpha case layer at elevated temperatures requires hot forming processes to be conducted either in inert atmosphere, or vacuum. Alternatively, alpha case could be removed post process by chemical milling which requires high capital costs as well as stringent safety measures. Alternative removal techniques are therefore under investigation and one such option is machining removal which can make use of the already established South African machining industry. Excessive wear due to the hardened alpha case layer results in machining removal not currently being viewed as economically feasible. This investigation therefore focusses on identifying possible machining guidelines for the removal of alpha case from titanium alloys. Thereafter, a comparison is made between machining removal of alpha case with chemical milling in the context of the South African manufacturing industry. It was observed that alpha case is readily removed at all machining conditions and that excessive notching and accelerated wear rates are experienced at high cutting speeds. Wear rates more commonly attributed with titanium machining is observed at lower cutting speeds.
Investigating the impact of tool velocity on the process conditions in incremental forming of titanium sheets
(Elsevier, 2017) Uheida, E. H.; Oosthuizen, G. A.; Dimitrov, D.
ENGLISH ABSTRACT: 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 developed profiles of the mechanical and thermal demands during the SPIF of titanium sheets are presented and discussed. Forming temperature and force were directly related to the tool rotation speed, higher temperatures and lower reactional forces correspond to higher speeds. At very high rotation, failure conditions occurred and the ability to shape a CP Grade 2 sheet is decreased; these failures were mainly due to extreme heating, leading to termination of the tests concerned. The main objective of the study is to gain a better understanding of the combined effects that the varied relative motions at the tool/sheet contact zone have on the process conditions.
Investigating the performance of custom manufactured cermet mounted points when grinding Ti6Al4V alloys
(Central University of Technology, 2017) Enever, A. A.; Oosthuizen, G. A.; Sacks, N.; Burger, M. D.; Oberholzer, J. F.
ENGLISH ABSTRACT: The use and implementation of mounted grinding points in industrial applications are wide spread, ranging from the bio-medical and automotive industries to the aerospace and mining industries. These smaller variants of the larger, more conventional grinding wheels are more affordable to produce, but equally effective in grinding applications. Generally, the abrasive materials implemented in the manufacturing of mounted points do not include the cermet WC-12-wt-%-Co, but rather use alumina- or silicon carbide. This study investigates the use of this WC-12-wt-%-Co cermet as abrasive medium. The resin was varied to manufacture two sets of cermet WC-12-wt-%-Co mounted points that contained 12-wt-% and 16-wt-% resin content, respectively. The grinding performance of these mounted points were evaluated in terms of the tool wear rate, the surface finish and the surface hardening of the Ti6Al4V work piece. The grinding tool wear rate of the 16-wt-% mounted points were more gradual than for the 12-wt-%. The 16-wt-% mounted points produced a smoother surface finish and work hardening occurred on most of the Ti6Al4V work piece surfaces.

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