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Metal injection moulding as a possible processing route for porous prostheses

  • Authors: Bhero, Shepherd
  • Date: 2014
  • Subjects: Metal injection moulding , Porous prostheses , Full-density prostheses
  • Type: Article
  • Identifier: uj:4903 , ISSN 2349-1442 , http://hdl.handle.net/10210/13001
  • Description: Metal injection moulding (MIM) can be used to make close to full density parts. The superiority of MIM over conventional casting and machining lies in lower cost and shorter processing time. Of paramount importance is the fact that powder processing circumvents the typical casting problems that include macro-segregation and discontinuities. Thus powder processing is a possible route for manufacturing full-density prostheses devoid of casting imperfections. However, the full density metallic part is much higher than that of bone tissue and would exert skewed weight on the skeletal configuration. This paper explores the feasibility of producing high strength porous prostheses in a bid to lower the overall implant density and to a lesser extent, stiffness, so as to match the bone properties as closely as possible. Powder characteristics and sintering parameters are critical in achieving the desired end.
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Barriers to information and communication technology use

  • Authors: Bhero, Shepherd
  • Date: 2013-07-10
  • Subjects: Information and Communication Technology , Computer literacy - Study and teaching , Digital divide
  • Type: Thesis
  • Identifier: uj:7599 , http://hdl.handle.net/10210/8465
  • Description: M.Com. (Business Management) , Information and Communication Technology (ICT) is pervasive in tertiary education, commerce and industry, yet many disadvantaged rural areas and townships lag behind in technological development. For example, in rural schools students have weak ICT background and consequently their progress at tertiary education level and career choices suffer, easpecially in the urban career context. This study sought to identify the urban-rural divide in ICT and determine the causes. Questionnaires were distributed to a purposive sample of 196 students at the University of Johannesburg, Doornfontein Campus. The results show that practical use of computers starts at high school ages between 11 and 15 years. The computer instructions are less pronounced. There have been some ICT development initiatives by government and some other organisations although not well coordinated. The resource needs for uninhibited expansion of ICT include computers, connectivity and skilled educators. Despite the current efforts, rural areas and townships lag behind for various reasons such as; technological under-development, low literacy levels and poverty. Thus students from these disadvantaged communities are constrained in career choices and also struggle to cope at university because of the demand for ICT ability. The pervasiveness of ICT in all walks of life has created a digital divide to the extent that township and rural folk remain marginalised although Internet cafes have played a part in making ICT somewhat accessible. The explosion in mobile telephony and its widespread use even in rural areas have immense potential for ICT growth. However, education and awareness campaigns on the utility of cell phones as a medium for ICT will be essential. A renewed focus on computer education in primary school learners will “catch them young” and revolutionalise the ICT in South Africa. The development in ICT will require further substantial investment in ICT infrastructure and hardware as well as improving the skills of educators. The digital divide need be closed so that marginalised rural areas and townships can also derive the socio-economic benefits that ICT bring. Education will raise the literacy thresholds, which will increase awareness of the potency of ICT. Use of local language and content on the Internet will enhance its cultural relevance and acceptability. ICT is a global phenomenon and South Africa cannot afford to take a back seat.
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Determination of the ductile to brittle transition temperature of Austempered ductile iron

  • Authors: Bhero, Shepherd , Mathabathe, Maria
  • Date: 2014
  • Subjects: Alloys , Iron founding , DBTT of ADI , Low temperature engineering
  • Type: Article
  • Identifier: uj:5092 , http://hdl.handle.net/10210/13682
  • Description: Austempered ductile iron (ADI) is a relatively new material that is increasingly finding space in industrial application. ADI possesses a unique combination of hardness and toughness that is not typical of most ferrous materials, where an increase in strength is invariably accompanied by a decrease in toughness and vice versa. Although the superiority of ADI is well documented in literature, there is still widespread scepticism application because not all properties are well known. This paper aims to determine the ductile to brittle transition temperature (DBTT) of ADI in order to establish its suitability for cryogenic applications.
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The cost of quality : elements of lean production in foundries

  • Authors: Bhero, Shepherd , Dlamini, Menzie
  • Date: 2015-07-14
  • Subjects: Lean manufacturing , Foundries , Cleaner production , Waste management
  • Type: Article
  • Identifier: uj:5214 , ISBN 9789384468170 , http://hdl.handle.net/10210/14498
  • Description: Inefficiencies in the process chain result in bloated operational costs and ostensibly pass on to the customer. It is essential to streamline process costs and categorise them appropriately as either costs of conformance or cost of non-conformance. In this way, hidden costs due to inefficiencies in the system can be identified. A sustained continuous improvement programme to systematically eliminate waste can be employed to achieve lean manufacturing or “cleaner production”. A number of factors contribute to costs in a foundry from procurement of scrap to the delivery of a casting.
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Hadfield steel and austempered ductile iron : similar in metallurgy yet different in chemistry, heat treatment and application

  • Authors: Bhero, Shepherd
  • Date: 2015-07-14
  • Subjects: Austempered ductile iron , Hadfield steel , Martensite , Austenite
  • Type: Article
  • Identifier: uj:5222 , ISBN 978-93-84468-17-0 , http://hdl.handle.net/10210/14508
  • Description: Hadfield steel contains high carbon above 1% manganese content above 11% to stabilise austenite at room temperature while ADI has low manganese content of typically less than 0.4% to suppress the precipitation of carbide during austempering. In ADI austenite is stabilised by dissolving carbon that diffuses from graphite nodules and pearlite (in the case of pearlitic ductile iron). The high silicon in the order of 2.6% promotes graphitisation. The heat treatment procedures for the two materials are also different. However, the resulting matrix of microstructure contains austenite, which is meant to transform to martensite by mechanism believed to be both strain-induced and strain-assisted once the material has been strained. The toughness of Hadfield steel and ADI found to be 90J and 8.3J for respectively. These were below the standard values. Similarly, tensile properties of Hadfield steel i.e. yield strength 338 MPa, UTS 568 MPa and elongation of 20% were all below values of the standard values confirming the inferior quality of the local product.
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Effect of built orientation on direct metal laser sintering of Ti-6Al-4V

Effect of build direction on the microhardness and dry sliding wear behaviour of laser additive manufactured Ti-6Al-4V

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