The parameter defined as ‘rake angle'—combining the shape of the wheel-dressing diamond with its orientation—has been introduced in conjunction with other associated dressing variables, such as the depth of cut and traverse rate, into an evaluation of the dressing process, and its subsequent influence on both rough and finish cylindrical traverse grinding. With the object of minimizing diamond wear, due to the high cost of dressing diamonds, the nature and magnitude of the components of the dressing force have been recorded by means of a three-component strain gauge-type dynamometer and Ultra Violet recorder. A linear relationship was established between the radial component of force on the diamond, and the amount of diamond wear.

Selective Laser Melting (SLM) is an additive manufacturing technology that consolidates layers of metal powder using a high power laser. The laser's small spot size and relative accuracy facilitates the production of high resolution parts with great complexity that would be otherwise difficult to manufacture using conventional manufacturing techniques (e.g. casting, machining etc.). The possibility to build thin wall high resolution parts complements the technology's main advantage and extends its manufacturing capabilities. The high heat input delivered by the laser and complex melt pool dynamics, requires that laser process parameters are carefully controlled in order to prevent solidified parts from exhibiting poor properties such as a high surface roughness and poor resolution.

Laser beam welding processes, with their inherent potential of controlling the energy input, give rise to new applications with respect to the manufacturing of optical active and compact laser diode beam assemblies. In electronics and fine mechanics, components require increasingly high strength joining technologies to replace the conventional gluing or soldering process. Alternative joining methods for commercial laser diode beam assemblies often reach their limits in terms of product quality and reliability. The objectives of this thesis, examined by the author, are as follows: The first objective is the development and validation of a semi-automatic laser fine welding station (pulsed Nd:YAG-lasers) with an automatic micro-alignment solution for optomechnical components. The second objective in the course of this work is the construction and manufacturing of new laser diode beam assembly (LDBA), taking into account the laser weldability of the components. This includes the development of a reliable laser fine welding procedure supported by a FE-analysis of the clamped components during welding.

There is a desire within both the stainless steel and automotive industries to introduce stainless steel into safety critical areas such as the crumple zone of modem cars as a replacement for low carbon mild steel. The two main reasons for this are stainless steel's corrosion resistance and its higher strength compared with mild steel. It has been anticipated that the easiest way to introduce stainless steel into the automotive industry would be to incorporate it into the existing design. The main obstacle to be overcome before this can take place is therefore how to join the stainless steel to the rest of the car body. In recent times arc brazil g has been suggested as a joining technique which will eliminate many of the problems associated with fusion welding of zinc coated mild steel to stainless steel. Similar and dissimilar parent material arc brazed joints were manufactured using three copper based filler materials and three shielding gases. The joints were tested in terms of tensile strength, impact toughness and fatigue properties. It was found that similar parent material stainless steel joints could be produced with a 0.2% proof stress in excess of the parent material and associated problems such as Liquid Metal Embrittlement were not experienced. Dissimilar parent material joints were manufactured with an ultimate tensile strength in excess of that of mild steel although during fatigue testing evidence of Liquid Metal Embrittlement was seen lowering the mean fatigue load. At the interface of the braze and stainless steel in the similar material butt joints manufactured using short circuit transfer, copper appeared to penetrate the grain boundaries of the stainless steel without embrittling the parent material. Further microscopic investigation of the interface showed that the penetration could be described by the model proposed by Mullins. However, when dissimilar metal butt joints were manufactured using spray arc transfer, penetration of copper into the stainless steel resulted in embrittlement as discussed by Glickman.

The many problems arising in manufacturing have led to the development of a new area of technology which Merchant has called "optimization technology" and has defined as being that area which facilitates operation of a manufacturing system at its minimum cost point, while helping to maximize performance by providing information and control. The most important areas of optimization technology are computer-related technology and variable programme automation. Variable programme automation deals largely with the direct automatic control of manufacturing operations, as in numerical control and adaptive control. This presents the possibility of the eventual realization of a fully automated self-optimizing integrated manufacturing system.

In this project, two new oxide cathode designs, namely the integrated oxide cathode and the two-layer/impregnated oxide cathode, and their respective manufacture processes were designed and developed. The two oxide cathodes were both produced from BaSr(CO3)2, Ni filaments and polymer additives. The integrated oxide cathode is a one component mixture of BaSrO2/Ni and the two-layer/impregnated oxide cathode consists of a porous Ni substrate with BaSrO2 impregnated on and in it. Casting and heating are the two most important steps of manufacturing both cathodes. The effects of various processing parameters during these two main steps on the properties of the resultant cathodes were investigated by TGA, EDX and SEM.

A novel powder processing technique has been developed by combining conventional powder injection moulding with polymer co-injection moulding, to permit the in-situ surface engineering of metal or ceramic components as an integral step within the processing cycle. The new technique has been used to produce surface engineered iron based components with either corrosion resistant or wear resistant surfaces, and to produce alumina based components with toughened surfaces. The most critical factor for the feasibility of surface engineered components is that the sintering profiles of the skin and core materials must be well matched or differential shrinkage or delamination will result. A particular requirement of surface engineering is the ability to control the surface engineered skin profile. Polymer injection moulding modelling software was applied to predict the surface engineered skin profiles of the surface engineered metal/ceramic components. Successful skin profile prediction is dependent on the characterisation of the feedstock materials being injection moulded. Several feedstocks have been characterised for their material properties and first pass models developed to predict the feedstock material properties as a function of their individual material properties and mass or volume ratios. It has been demonstrated that the design of the feedstock composition and injection moulding process conditions can be optimised by the use of computer-based injection moulding modelling software to achieve the desired surface engineered skin profile. A methodology has been developed that outlines all the stages necessary for successful powder co-injection moulding.

This thesis describes the formulation of a ternary thermosetting adhesive which consists of a diglycidyl ether of bisphenol-A (DGEBA) epoxy resin cured with 3,3’-diamino diphenyl sulphone (3,3’-DDS) hardener and modified through the addition of carboxyl- terminated butadiene-acrylonitrile (CTBN) rubber and multi-walled carbon nanotubes (MWCNTs). Processing implications of the novel adhesive in the film form are considered in order to manufacture bonded specimens for characterisation of the adhesive performance in structural joints. The ternary blend which represents the novel adhesive formulation is also characterised in bulk form. The cure kinetics behaviour of the novel ternary blend is investigated using differential scanning calorimetry which shows 10% reduction in the total reactivity, and therefore reduced final crosslinking density, with the addition of the carbon nanotubes. A cure kinetics model is developed for the novel ternary thermoset. From characterisation of cast samples, a toughening effect of the phase separated rubber particles is observed, from 144 to 317 J/m 2 , with a further increase to 551 J/m 2 in the presence of the carbon nanotubes. In the absence of rubber, the nanotubes alone produce a minimal effect upon the thermo-mechanical and mechanical characteristics of the resin. The morphology of the cured material is affected by the presence of the nanoparticles, resulting in the reduction of the mean rubber particle size from 3µm to below 1µm. The electrical conductivity of the cured resin samples is found to increase by six orders of magnitude, up to 3.6 x10 -3 S/m in the ternary blend for a low carbon nanotube concentration of 0.3 wt%. DCB and ELS tests are used to study the performance of the novel adhesive in a joint configuration. The adhesive joint strength is dependent on the substrate type as well as on the surface preparation. The novel adhesive is also examined under fatigue in a ‘bonded crack retarder’ application.

According to recent estimations, the construction of pipelines will continue to increase during the next thirty years, in particular as a result of oil and gas discoveries in remote locations. Significant advances in welding technology during the last ten years have potential to provide improvements in productivity, quality and structural integrity of pipe girth welds. In this thesis, several new processes Lincoln STT, Lincoln RapidArc, Fronius CMT, Fronius CMT-P and Kemppi FastROOT have been compared the first time to the GMAW-P to understand how these new waveforms operate for pipe welding. The process setting parameters have been analysed to understand their effect on metal transfer and arc stability control, and on bead shape characteristics. Although all waveforms present similar burn-off ratios, individual waveforms differ considerably, and especially the arc voltage waveform. This leads to considerable differences in the mechanism of metal transfer and the stability of the processes under similar experimental conditions. Understanding of these new waveforms in terms of the effect of setting parameters in the mechanism of metal transfer, process stability and melting phenomena provides a basis for assessing the potential of these processes for a range of applications, and in particular application to CRA pipe root welding Since the arc energy is the overall energy delivered from the power source at the contact tip of the torch, and part of that energy is not absorbed by the workpiece, research was performed to measure the process efficiency associated with some of these waveforms and process setting conditions. The study led to a better understanding of the potential errors in calculating process efficiency. The results obtained show that all the short-circuiting waveforms analysed (i.e. CMT, STT and FastRoot) had a similar process efficiency of 90±3%, while pulse spray waveforms (GMAW-P, CMT-P and RapidArc) are characterized by lower process efficiency, approximately 78±3%. The application of these waveforms to the welding a narrow groove pipe with a “J” groove design was investigated. These analyses were focused on the variation of bead shape characteristics and welding quality performance based on the analysis of the conditions that result in lack of penetration and top bead defects, such as lack of side wall fusion or undercutting. It was observed that RapidArc and CMT-P are able to satisfy the quality requirements, i.e. full penetration and absence of defects for the specific conditions described in this thesis. High welding speeds (up to 1m/min) were achieved with these processes, four times the typical speed 0.25m/min. Finally, the shielding gas plays an important role in terms of quality and weld bead performance. This led to an optimization of the shielding gas composition used, based on mixtures of carbon dioxide, argon and helium. Statistical modelling was undertaken to optimize the shielding gas mixtures using RapidArc and CMT-P waveforms. In parallel, a new purging shielding gas device was designed to achieve a weld root free of oxidation.

The aim of this research was to study the effectiveness of a typical oilfield corrosion inhibitor, which is considered to be a green inhibitor (non toxic to the environment) in controlling internal corrosion of welded X65 pipeline steel in brines saturated with carbon dioxide at one bar pressure, under dynamic flowing conditions, over a range of temperatures. Several experimental configurations were used ranging from a simple flat plate design to a novel rotating cylinder electrode, to allow high shear stress to be achieved. The rotating cylinder electrode (RCE) apparatus was designed to allow steel from the weld metal, heat affected zone (HAZ) and parent material to be galvanically coupled and tested in high shear stress conditions. In producing the RCE, the three regions of the weld were identified by optical metallography and samples of each were machined to produce cylindrical electrodes, which were mounted on a motor driven shaft. Electrical connections were made to the three electrodes via a high quality slip-ring assembly. The galvanic currents flowing between the regions of the weld were recorded using zero-resistance ammeters and their self-corrosion rates were found by uncoupling the electrodes and performing polarization resistance measurements. For static conditions the inhibitor had an effective performance and after a short initial period during which film formation took place, at longer exposure times a dramatic reduction of corrosion rate was obtained. Under flowing conditions, both the galvanic currents and the self-corrosion rates were found to increase with the shear stress, as the rotational speed of the RCE was increased. The total corrosion rate of each weld region was assessed from the sum of the self-corrosion and galvanic contributions. In most cases, the weld metal and HAZ were shown to be cathodic to the parent material and this was considered to be a desirable situation as localised corrosion of the weld was minimised. However, in some circumstances, including inhibition of pre-corroded steel surfaces, a current reversal took place, which resulted in accelerated corrosion of the weld. These findings are explained in terms of the protective nature of the films that form on each region of the weld.