Pulsed ytterbium-doped fibre lasers based on a master oscillator power amplifier (MOPA) architecture possess attractive characteristics over their Q-switched diode-pumped solid-state counterparts. These include a relatively low cost of ownership and a flexible operating window with respect to the pulse duration, shape and repetition rate. For micro machining applications, given this inherent large processing window available with respect to the pulse characteristics, the effect of process parameters on particular machining outcomes needs to be investigated. The literature review conducted identified four important gaps in the knowledge surrounding the nanosecond fibre laser machining of materials. These gaps included the optimisation of the nanosecond fibre laser machining during milling operations, with the aim of obtaining both high surface quality and material removal rates, as well as the need for complimentary theoretical and experimental studies on the basic nanosecond laser material interaction for a wide range of engineering materials. In addition, the characterisation of the nanosecond laser machining of bulk metallic glasses, and the investigation of processing conditions leading to crystallisation of their amorphous structure, were identified as knowledge gaps that need to be addressed. The first knowledge gap was the focus of Chapter 3. The particular parameters under investigation in this study were the pulse duration and repetition frequency, the pulse overlap, the scanning strategy and the distance between linear machined tracks when processing aluminium. The results showed that, for each of the pulse durations studied, the specific frequency at which both the highest energy and average power are delivered leads to the maximum material removal rate (MRR) achievable, and to high values of surface roughness. It was also observed that the lowest surface roughness obtained corresponds to a specific frequency range which is common for all pulse durations. Following this, a design of experiments was conducted for a given pulse duration with the aim of identifying an optimum combination of parameters with respect to the attained surface roughness while operating at the frequency resulting in the highest MRR. This optimisation study resulted in a 60% decrease in the achieved surface roughness and also showed that the distance between machined tracks had the highest influence on the surface finish among the parameters considered. In the following chapter, a theoretical model was developed to predict the topographical evolution of the single pulse craters as a result of the time-dependent temperature rise in the processed materials when the laser beam is incident on its surface. In addition to this theoretical study, in an to attempt to understand the laser material interaction on a more fundamental level, single pulse experiments were conducted at varying laser fluence values and pulse durations leading to the formation of single craters on the surface of a number of materials namely, titanium, silicon and silicon carbide. In particular, different pulse lengths were investigated at decreasing values of fluence until no visible effect on the material surface could be observed. Based on this investigation, the fluence corresponding to the ablation threshold for each material at different pulse durations could be found whilst identifying the relationship between the laser processing parameters and the dimensions of the single craters. Scanning Electron Microscopy (SEM) micrographs of the craters were also used to observe phenomena such as melt ejection as a result of varying the process parameters. The experimental results were compared with the theoretical predictions and a good agreement between both set of data was found with respect to the achieved depths and diameters of the craters. The additional knowledge gaps were the focus of Chapter 5. In particular, the characterisation of nanosecond laser machining of a zirconium-based bulk metallic glass (BMG) was conducted using the approach employed in Chapter 4. Similar conclusions were reached with regard to the single pulse material removal behaviour when varying the fluence and pulse duration. In addition, milling of the material with different parametric combinations was implemented to investigate the crystallisation behaviour of the BMG. To complement these experimental tests, the theoretical model reported in Chapter 4 was further developed to predict the heating and cooling rates of the milling process. From this study, it was found that varying the process parameters of the machining of BMG results in a variation in the critical cooling rate (from the melt temperature to the glass transition temperature) which may result in crystallisation of the material.

Nowadays, New Product Development (NPD) has become a business priority in manufacturing companies due to international competition in terms of meeting higher and changing customer requirements, generating high profit at low cost, and maintaining sustainable development and growth. Through literature review and industrial investigations, it has been recognised that NPD is an information and knowledge intensive process. However, in current practice, enterprise knowledge is not properly managed or easily accessible. Many service providers have not followed the good practice of considering business objectives and end users’ requirements as main drivers of knowledge management system development and implementation. This doctoral thesis presents a methodology for the design and development of Knowledge Management (KM) systems to support NPD based on Enterprise Architecture Frameworks (EAFs). The project focuses on IT system specifications generation driven by business and knowledge users’ requirements in the automotive industry. Current EAFs have been developed by researchers and practitioners to help enterprises to design their information systems based on business objectives and user requirements. However, these frameworks are mainly proposed to manage information and data such as finances, resources, management and engineering documents, not for the increasingly important enterprise knowledge, especially tacit and unstructured knowledge. This project aims to extend the capabilities of the latest enterprise architecture frameworks so that not only data and information, but also enterprise knowledge can be managed. A guideline in the form of a flowchart has been developed, which provides a process that can be followed and used by system developers and implementation. The extended EAF has been implemented as easy-to-use folders for the development of a structured knowledge base. A case study in an automotive company proved that the methodology can be used to produce the functional specifications of their IT systems to include knowledge management capability. The system specification can then be used, either to assess a company’s existing information systems and direct its future system development and implementation; or to develop/implement a complete new information system from scratch.

Manufacturers are the leaders in developing new products to drive productivity. Higher productivity means more products based on the same materials, energy, labour, and capitals. New product development plays a critical role in the success of manufacturing firms. Activities in the product development process are dependent on the knowledge of new product development team members. Increasingly, many enterprises consider effective knowledge search to be a source of competitive advantage. This research presents an exploratory case study conducted at an aircraft manufacturer. This investigation uncovered six, empirically derived and theoretically informed, problems to enterprise knowledge search. They have been articulated as (i) the effectual web bandwidth limits search speed; (ii) less relevant search results based on word-frequency recognition models of search engine; (iii) un-useable techniques for enterprise search; (iv) rigour security, reliability, and company policy; (v) poor search performance about unstructured enterprise knowledge; (vi) the lack of tacit knowledge sharing. Existing search methodologies have focused on the internet search, rather than providing effective search for enterprise. This research aim is developed to assist the manufacturing enterprise in meeting the industrial requirements in the following way: a methodology and system that can improve the information and knowledge search performance in new product development process. Based on the exploratory case findings, a knowledge search methodology and system has been developed. Agent technology is used to fulfil the requirements of enterprise search. Some initial tests were conducted to better understand implementation issues and future deployment of the methodology and system in practice.

Dosators (and other machines operating on generally similar principles) are widely used in the pharmaceutical industry for dosing products that are delivered to the customer in powder form (i.e. capsules and dry inhaled powder applications). However a significant problem for this technology is the ability to predict how accurately and reliably, new formulations can be dosed from these machines prior to scale-up for manufacture. Dosator filling machines have been on the market for over forty years, and their mechanisms have been refined over the time; in parallel with development work of formulation scientists. Despite the work that has progressed in both of these important fields, there has been only a limited improvement in the understanding of how the formulations behave when introduced into production line equipment. Typical problems include variation in potency and manufacturing dose weight – both being issues that can be difficult to predict and counter (especially where mainly the manufacturing process is undertaken on a batch basis). Many manufacturing problems can be traced back to an inadequate understanding of the bulk properties of the powders at the formulation stage. Common issues encountered during full scale production include extended commissioning; high levels of out of specification materials (specifically through dose weight variation). The project aims to provide a predictive tool to industry, the use of which can improve manufacturing efficiency, minimise costs and risk when launching new products. The approach proposed focuses on the development of an analytical model for the pick up and discharge of powder into and out of dosators, based upon established particle/powder characterisation techniques combined with an improved understanding of dosator machine factors, constitutive models and geometry of the machine. The model will be used to predict fill dose weights and filling/discharge behaviour of new products in dosator fillings systems; likewise, to investigate what changes in powder flow properties mean to dosator operation. Recommendations for the practical use of flow property measurement techniques in conjunction with the model are also outputs from this project. To simulate the process and (very importantly) validate the model, a dosator single shot testrig was engineered at The Wolfson Centre to measure forces acting on the dosator during the filling stage, the force required to eject the dose and the dose weight. In addition other important aids, such as a dosator demonstrator and an ultimate bearing application of soil mechanics, are key in the understanding of the process and estimate the stress distribution occurring in the stages of the operation. In addition, the development of this research provides a better understanding of the compaction phenomena in dosator operation, and more importantly, critical flow properties and machine settings factors compromising the uniformity of the fill dose weight in production lines using dosator filling machines not mentioned in the literature yet. Although this project has focussed on dosators, the general concept could be applicable to other volumetric powder filling systems.

Sonca is a manufacturing operation producing torches and lanterns. In order for the Company to be competitive, one of the key factors is to introduce new products to market quicker and at a lower total product cost. A system titled "concurrent integrated design and assembly planning (CIDAP)" is developed to aid this process. It is identified that methods proposed by other researchers using different algorithms are not interactive enough and need too much space to store the representation of assembly sequences and time to process the assembly operations for a complex assembly. Besides, the commercially available systems and software are not integrated and are too universal. The data used is not compatible with the company's data file. The CIDAP framework focuses on concurrent and integration, in that the different processes in the whole product development cycle are carried out concurrently and are integrated. In the framework two techniques, namely KALG (Knowledge-based Assembly Liaison Graph) and KPN (Knowledge-based Petri Net) and four expert systems for selection of assembly system, feeder, gripper, and sensing technology are developed. Commercially available software such as Boothroyd and Dewhurst's DFMA (Design For Manufacture and Assembly) software, Rapid Prototyping and Quick Tooling are also applied in the framework. The frame work and the systems are applied to an actual case in designing a series of torches within the Company. Results show that the product development cycle time is improved by 25%, rework cost reduced by 20%, and final product cost reduced by 11 %. The Company has adopted the new framework. The developed systems and data files are not only applicable to the Company, but also to other small and medium size companies in Hong Kong and China with a similar scale and nature of operation.

No description available.

This thesis reports research into the specification and implementation of an Information Technology (IT) Route Map. The purpose of the Route Map is to enable rapid design and deployment of IT solutions capable of semi-automating business processes in a manufacturing enterprise. The Map helps structure transition processes involved in “identification of key business strategies and design of business processes” and “choice of enterprise systems and supporting implementation techniques”. Common limitations of current Enterprise Resource Planning (ERP) systems are observed and incorporated as Route Map implications and constraints. Scope of investigation is targeted at Small to Medium Sized Enterprises (SMEs) that employ Engineer-To-Order (ETO) and Make-To-Order (MTO) business processes. However, a feature of the Route Map is that it takes into account contemporary business concerns related to “globalisation”, “mergers and acquisitions” and “typical resource constraint problems of SMEs”. In the course of the research a “Business Strategy Driven IT System Concept” was conceived and examined. The main purpose of this concept is to promote the development of agile and innovative business activity in SMEs. The Road Map encourages strategy driven solutions to be (a) specified based on the use of emerging enterprise engineering theories and (b) implemented and changed using componentbased systems design and composition techniques. Part-evaluation of the applicability and capabilities of the Road Map has been carried out by conducting industrial survey and case study work. This assesses requirements of real industrial problems and solutions. The evaluation work has also been enabled by conducting a pilot implementation of the thesis concepts at the premises of a partner SME.

Process chains are regarded as viable manufacturing platforms for the production of Microand Nano Technology (MNT) enabled products. In particular, by combining several manufacturing technologies, each utilised in its optimal process window, they could benefit from the unique advantages of high-profile research technologies such as the focused ion beam (FIB) machining. The present work concerns the development of process chains and the investigation of pilot cost-effective implementations of the FIB technology in manufacturing platforms forfabrication of serial replication masters.

It is known that chemical and physical features of bone contribute to its functionality, reactivity and mechanical performance. This knowledge is the fundamental rationale for this project. The aim of this thesis is to study the influence of synthesis conditions on material composition and ultimately the biological performance of hydroxyapatite (HA) as well as to fabricate scaffold structures that physically emulate bone tissue. Concurrent characterisation of physiochemical properties and evaluations of in-vitro cytocompatibility, and the degree of osteoblast proliferation on CDHA substrates precipitated under different reaction conditions provides a novel contribution. Non-viability of cells seeded on substrates prepared in a solution adjusted to pH 10 (AP07) was confirmed after 1 day of culture. Dead cells were also observed after 3 days on CDHA prepared at 70°C under a controlled pH level of 11 (AP12). XRD found no discernible difference between these samples and CDHA substrates shown to be cytocompatible. The source of cytotoxicity was concluded to be the presence acidic DCPD in AP07, and positive surface charges for AP07 and AP12 that were revealed by FTIR, DTA-TGA and ZP measurements. Control of pH, increased solute concentration, the use of Toluene, and substitutions of 10mol% Mg or 2mol% Zn were shown to enhance the proliferative rate of cells seeded on CDHA synthesised at RT. CDHA prepared in a 60 Toluene: 40 DI water (% v/v) solvent system with a lower dielectric constant (AP14) exhibited marked XRD peak broadening and 20% larger surface area compared with CDHA prepared in DI water (AP09). These features are suggested to explain the enhanced proliferation of cells on AP14, which was shown to be more than double the fluorescence exhibited for AP09 after 7 days. XRF was used to confirm the presence of Sr, Mg, and Zn that were selected due to their key biological roles in bone apatite. Evidence of lattice incorporation of these divalent cations was supported by XRD analysis that demonstrated shifts of characteristic HA peaks. Mg ions inhibited the crystallisation process, which caused a 45% reduction in the crystallite size, 60% increase in particle surface area and thermal conversion to whitlockite at 600°C. The relatively low crystallinity and larger surface area of Mg and Zn doped substrates is proposed to explain the respective 80 and 40% increase in cell proliferation compared to a pure sample prepared under the same conditions. Flowability of HA:PVOH precursor materials correlated well with the mechanical stability, microstructure and porosity of 3D printed scaffolds. Anisotropic behaviour of constructs and part failure at the boundaries of interlayer bonds was highlighted by compressive strength testing. A trade-off between the ability to facilitate removal of PVOH thermal degradation products during sintering and the compressive strength of green parts was revealed. The maximum green scaffold strength of 0.85MPa was exhibited by parts that were air or vacuum dried for 6hrs. Critically, the pores of 3D printed constructs could be user designed ensuring interconnectivity and the imperfect packing efficiency of precursor powders created an inherent surface roughness and microporosity within scaffold struts. These features are known to be favourable for osteogenesis, osteoconduction and osteointegration in-vivo. This work establishes that changes to precipitation conditions cannot be deemed trivial since they may alter material composition, which ultimately determines cytocompatibility as well as the proliferative rate of cells. Due to the highly complex structure of bone there are understandably a number of on-going medical challenges and while the application of 3D printed HA bone tissue scaffolds is promising, the name apatite derived from the Greek ‘απαταο’, meaning to deceive is concluded to be very fitting.

This research concerns the development of a risk analysis and mitigation methodology for assessing the impact of uncertainties and complexity of the design requirements arising in new process and product developments in micro and nano manufacturing. The risk analysis methodology integrates different computational approaches for process and product analysis, including the reduced order modelling using design of experiments, risk analysis using sampling-based and analytical methods and optimisation techniques. The integrated risk analysis and optimisation methodology is applied to two applications: (1) the FIB sputtering process control, and (2) a flip chip design. Three different FIB processes using different ion sources were investigated in order to evaluate their process performance with respects to different process parameter uncertainties. A critical comparison of the process capability against the specification limits of different processes was studied. As parts of the research, a new modified computational model is developed for a material sputtering process using focused ion beam (FIB). This model allows the analysis of micro- and nano-structures shape with the FIB machine controlled through multiple beam scans and different beam overlapping. The FIB model related studies also address the modelling requirements for including material re-deposition effects that occur during FIB milling. The model has been validated using an experimental test case. Good agreement is observed between the analytical shape using the model and the actual experiment. The validated model enhances the accuracy of the dwell time prediction. This approach overcomes the dependence of a trial-and-error approach of the process control in nano-manufacturing industry. The proposed methodology is also used to address a design problem of a flip chip design. A novel method for the evaluation of the environmental impact of the flip chip design in a multi-disciplinary optimisation problem is proposed. The goal is to address materials constraints due to environmental regulations and to handle different types of requirements such as the reliability and cost. An optimal flip chip design reliability function is identified. The approach allows electronics manufacturers to consider the environmental impact amongst different design alternatives at an early stage of the design of the product before any real prototyping in order to reduce the total manufacturing life cycle.