The thesis reports an investigation concerned with the optimisation of materials and methods in the production of precision cast H13 die steel tooling. The investigation was conducted in four stages: (i) mould material evaluation; (ii) metallurgical processing; (iii) test casting production and evaluation; (iv) finishing procedures.

The objective of the current work was to establish a viable manufacturing technology for 1-3 piezoelectric ceramic/polymer composites, capable of meeting the high volume production requirements. To this end, an extensive development and fabrication programme has been successfully completed, which demonstrates the feasibility of the injection moulding process as a potential fabrication route. The technology will make available to the MOD a new generation of low-cost transducers tailored to perform in the frequency range suitable for underwater applications. The piezoelectric ceramic used throughout this study was PZT-5H. During the course of the investigation two types of feedstock formulation were evaluated. The first employed a binder system developed in-house based on polypropylene, microcrystalline wax and stearic acid. The second formulation employed a commercial binder system designed specifically for ceramic/metal injection moulding. In the case of the 'in-house' binder, two formulations were prepared with approximately 62% by volume PZT-5H but with differing ratios of polypropylene to microcrystalline wax. Three formulations were prepared with the 'commercial' binder system containing approximately 55%, 58% and 60% by volume PZT-5H respectively. Compounding by twin screw extrusion produced a feedstock consisting of discrete particles of PZT-5H, approximately 0.5 ?m in diameter, homogeneously distributed within the organic binder. All formulations displayed shear thinning behaviour when evaluated by capillary rheometry and had shear viscosities below 1000 Pa s at a shear rate of 100 s-1 Further, all formulations displayed tension thinning behaviour-and were characterised as viscoelastic. Attempts to produce an acceptable 1-3 preform moulding from feedstock based on the in-house binder system were unsuccessful. It was necessary to reduce the ceramic loading to 30% by volume before a complete 1-3 preform could be moulded. The failure to mould preforms from the in-house formulation was attributed to its high elongational viscosity. It was therefore concluded that an elongational viscosity of 30 kPa s at a tensile strain rate of 58 S-1 is undesirable for moulding this particular component. Satisfactory conditions were established for the production of 1-3 preform mouldings from the commercial feedstock formulation containing 58% by volume PZT-5H. Optimisation of the injection rate and hold pressure was possible by investigating the variation in pillar-density across the 1-3 preform mouldings. Satisfactory heating schedules for both the binder removal and sintering stages were established. Microstructural characterisation of sintered pillars revealed grain sizes ranging from 2 to 7 ?.m in diameter. Orientation effects in the sintered microstructure were not apparent in samples moulded at different injection rates. The addition of cover plates to poled composites containing epoxy resin was found to increase the hydrophone figure of merit (HFOM) by an order of magnitude. HFOM values measured during the present work for injection moulded 1-3 composites are comparable with similar composites fabricated by the dice-and-fill technique.

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The purpose of this thesis is to improve the 'art' of early capital cost estimation of chemical process plants. Capital cost estimates are required in the early business planning and feasibility assessment stages of a project, in order to evaluate viability and to compare the economics of the alternative processes and operating conditions that are under consideration for the plant. There is limited knowledge about a new plant in the early stages of process development. Nevertheless, accurate cost estimates are needed to prevent incorrect decisions being made, such as terminating the development of a would-be profitable plant. The published early capital cost estimation methods are described. The methods are grouped into three types of estimate: exponent, factorial and functional unit. The performance of these methods when used to estimate the capital costs of chemical plants is assessed. A new estimating method is presented. This method was developed using the same standard regression techniques as used in the published methods, but derived from a new set of chemical plant data. The effect that computers have had on capital cost estimating and the future possibilities for the use of the latest computer techniques are assessed. This leads to the fuzzy matching technique being chosen to develop a new method for capital cost estimation. The results achieved when using fuzzy matching to estimate the capital cost of chemical plants are presented. These results show that the new method is better than those that already exist. Finally, there is a brief discussion of how fuzzy matching could be applied in the future to other fields of chemical engineering.

Selective laser sintering (SLS) is a rapid prototyping process, which operates by using a laser to locally heat an area within a layer of powder material, causing it to fuse together, creating a thin cross-section of solid material. 3D shapes are built by repeatedly depositing a layer of fresh powder on top of the cross-section and then locally heating it, causing it to fuse together and to the layer beneath. However, during SLS processing, temperature differences that exist in different regions of the fabricated parts lead to uneven shrinkages. The shrinkages cause surfaces in the part, which are intended to be flat, to exhibit a curved profile; a phenomenon termed curl. The development of curl is highly influenced by the SLS machine parameters selected in fabrication. The production of geometrically acceptable parts involves numerous fabrication trials before the optimum machine parameters can be found. The procedure can be time consuming and expensive. The aim of the work presented in this thesis was to develop finite element models for the purpose of predicting curl in SLS fabricated polycarbonate parts. The ultimate goal was to use the models to estimate the optimum SLS machine parameters for the physical fabrication of geometrically acceptable parts, produced in any material, and therefore avoid the costly and time consuming process of using SLS machines for experimental purposes. The prediction of curl was made through heat transfer and stress finite element models that were both coupled using the sequentially coupled thermal-stress analysis technique. Experimental work was carried out to measure material properties used as input to the models and to validate results predicted. The sensitivity of curl predicted to assumptions considered in the heat and stress models was introduced, and the assumptions highly influencing the accuracy of curl predictions were identified.

James Womack and his colleagues Daniel Jones and Daniel Roos changed the way western civilization approached manufacturing. In 1990, they published a book called ‘The Machine That Changed the World: The Story of Lean Production’. It was a concept that had slowly filtered from the east but had not made its mark on the manufacturing sector. The concept of lean, born out of the Japanese Toyota Manufacturing System, was first thought to be impossible to duplicate outside of Japan. Since Womack and company popularised this “new” way of producing goods and delivering services it spread across industries finding popularity in the medical, engineering, accounting and especially the manufacturing industries. Over the last few decades lean practices has been synonymous with efficiency, cost reduction, supply chain optimisation and innovative problem solving (Anvari Norzima, Rosnah, Hojjati and Ismail, 2010; Pieterse et al., 2010; Womack et al., 1990). Lean process implementation has been researched in abundance, as has failed attempts at lean implementation. The purpose of this study was to identify and assess enablers of lean sustainability in organisations where lean processes are already being implemented. The literature study found Organisational Culture, Leadership, Employee Engagement and Trade Unions participation as factors that contributed to successful lean implementations. The author developed a model to test Organisational Culture, Leadership, Employee Engagement and Trade Unions as enablers to sustain lean practices in organisations in South Africa’s manufacturing industries. The results proved that Organisational Culture, Leadership and Employee Engagement were considered enablers for lean sustainability. These three enablers have an interlinked relationship and together help sustainability. Lacking just one factor would surely result in unsustainable lean practices. The study was conducted in the quantitative paradigm, as the hypothesised relationship was statistically tested. The data was collected from a homogenous group via an email sent with a link to the questionnaire. The data was statistically analysed with Statistica software and Microsoft Excel.

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