The development of a high mean power laser, designed as a prototype for future machine tools, is described. The laser operating characteristics are measured and the output calibrated by means of a cone calorimeter and a photo-diode monitor. The cone calorimeter is compared with two commercially available calorimeters. The cooling of laser cavities is discussed and a theoretical treatment of the liquid cooling of high mean power pulsed lasers developed. The drilling process is investigated both theoretically and experimentally. The theoretical treatment proposes that liquid ejection is the principal means of mass removal and examines the two most probable causes of liquid ejection. The relevant thermophysical properties of liquid metals are collated and theoretical and empirical methods for the prediction of those properties not yet experimentally determined are outlined. High speed photography is used to investigate the ejection of material during drilling. Two distinct types of ejecta are identified and their velocities measured by streak and schlieren photography. Further, the influence of impurities within the metal on the drilling performance is investigated in an attempt to determine whether nucleation is the prime cause of liquid ejection. Finally, the most useful directions of research and development are suggested and further experiments are described which would add considerably to the evidence available on the drilling mechanism and thereby help to improve drilling performance.

High power ultrasonics is currently under-utilised as a manufacturing technology. The potential of the technology in areas such as welding, fastening and cutting has not been fully realised because the beneficial mechanisms available in ultrasonic systems are not always understood and therefore are not fully utilised. The empirical approach to much of the design process often results in unreliable operating performance in customised tools. The aim of the research reported in this thesis, is to develop a structured approach to the design and optimisation of high power ultrasonic systems. Furthermore, this research demonstrates how the use of such an approach can benefit the understanding of the fundamental ultrasonic process, which in turn leads to more informed system design criteria. Initially a combined analytical and experimental approach is proposed and is demonstrated using an ultrasonic welding tool as the focus. Finite element analysis is used to predict the vibration behaviour of the welding tool and models are validated by experimental vibration analysis techniques; electronic speckle pattern interferometry and experimental modal analysis. It is determined that the problematic behaviour of the welding tool results from high modal density and modal coupling, both of which are common problems associated with high power ultrasonic tooling. Sensitivity analysis with degree of freedom ranking using finite element analysis, detunes the coupled flexural vibration from the operating frequency of the system, successfully isolating the required response. The approach is extended to ultrasonic fastening, whose performance is known to be influenced greatly by fastener geometry. The technique is applied to develop a series of fasteners, each having an alternative critical vibration parameter during insertion. Insertion tests demonstrate that a particular torsional mode family promotes improved insertion performance and resulting join quality. Finally the approach is extended to a novel ultrasonic cutting application. The potential of the cutting process is assessed using finite element analysis to verify the cutting mechanism as one of controlled crack propagation which is dependent on the vibration characteristics of the cutting blade. Using a combination of vibration analysis and fracture analysis, the ultrasonic cutting process is optimised for blade mode of vibration, leading to improved cutting performance and control. A significant advance is made in the understanding of the fundamental mechanisms of ultrasonic cutting and in cutting system design.

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Achievable cutting distance of a diamond tool during turning is finite and is a limiting factor in the size of component that can be turned. This limit is particularly problematic when attempting to turn brittle materials, such as those used in infra-red optics. Natural diamond tools have been used for this application. However natural diamond introduces problems: the gems can contain possible contamination with a range of impurities and strong residual stresses from formation. Cutting distance is therefore inconsistent when using natural diamond. Industry is keen to increase possible cutting distance and to increase the consistency of cutting distance. One possible solution is synthetic diamond materials. New CVD single crystal synthetic diamonds possess high purity and consistent growth conditions and therefore have the potential to be a superior tool-material that provides longer achievable cutting distance and extremely consistent cutting behaviour. This new material is compared against natural and HPHT synthetic diamonds in machining tests against silicon workpieces in a selection of tool-orientations. Aluminium workpieces are machined with MCC and natural diamond tools to assess the performance of the new material against this commonly diamond turned material. While analysing the results from these cutting trials the failure modes of diamond tools were examined closely, resulting in discovering the existence of two separate failure modes and the development of a new wear-model. Natural diamond tools were carefully tested using a range of techniques hoping to find a root cause of the wide variability seen. FTIR offered a strong clue as to the defect within natural diamond tools that leads to occasional high cutting life.

Spiral jet milling is a size reduction process used in various industries, ranging from paints to food and pharmaceuticals. It has great benefit in the pharmaceutical industry due to its ability to reduce particulate solids to micron sizes and narrow size distributions. Despite its heavy usage, the underlying size reduction mechanism of the mill is not well understood. However it is generally known that the milling behaviour is dependent on the grinding conditions of the mill, as well as the materials physical and mechanical properties. The system is also very energy inefficient. In this work the milling behaviour of active pharmaceutical ingredients and excipients in the spiral jet mill has been analysed based on their mechanical properties, as established from the Ghadiri and Zhang semi-brittle breakage model. Using the Single Particle Impact Test Rig, the breakability index (αH/KC2) of three pharmaceutical materials (paracetamol, aspirin, and α-lactose monohydrate) is determined. It is shown that the order of breakability is paracetamol > aspirin > α-lactose monohydrate. For milling studies the Hosokawa Alpine Aeroplex Spiral Jet Mill 50AS is used. The change in specific surface area (ΔSSA) due to milling is quantified by size analysis and related to the breakability indices. The order of ΔSSA is α-lactose monohydrate > paracetamol > aspirin at high grinding pressure conditions. The loading of particles in the grinding chamber of the mill is found to be an important characteristic for the classification of milled materials in addition to the effects of centrifugal and drag forces. Numerical simulations have been carried out and used to analyse the behaviour of the spiral jet mill. Using Computational Fluid Dynamics, the mechanics of internal particle classification by size of the 50AS has been analysed. Particles of 2 µm and less are shown to be classified. The Discrete Element Method is coupled with Computational Fluid Dynamics to investigate the effect of grinding conditions and particle properties on the particle motion and fluid-particle energy transfer, including gas pressure, the number of particles and the particle size distribution. A very small amount of energy is transferred to the particles from the fluid, highlighting the energy inefficiency of the system. Interparticle interactions are found to have a greater amount of dissipated energy compared to particle-wall interactions, which suggests interparticle collisions are the primary source of particle breakage. The majority of the stress exerted on the particles is close to the wall of the mill, with the normal stress being greater than the shear stress. A very low proportion of particles are found to be in contact at a given time, indicating particle breakage occurs from instantaneous collisions rather than particles shearing against each other. Finally the potential for scale-up of the spiral jet mill is investigated based on the fluid power input to the system. There is a good comparison of the ΔSSA of α-lactose monohydrate milled in four different mills at similar fluid power input conditions. Two of the mills are the 50AS and the Hosokawa Alpine Piconizer (33 AS), and the other two are of different design but with internal diameters of 2 inches and 4 inches, i.e. roughly similar size to the Hosokawa mills. The latter two mills had a greater fluid power as the grinding nozzle diameters are larger than the Hosokawa mills.

Rotary planing is one of the most valuable machining operations in the timber processing industry. It has been established that cutting tool inaccuracy and forced vibration during the machining process are the primary causes of surface quality degradation. The main aim of this thesis is to design a control architecture that is suitable for adaptive operation of a wood planing machining in order to improve the quality of its surface finish. In order to achieve the stated goal, thorough understanding of the effects of machine deficiencies on surface finish quality is required. Therefore, a generic simulation model for synthesising the surface profiles produced by wood planing process is first developed. The model is used to simulate the combined effects of machining parameters, vibration and cutting tool inaccuracy on the resultant surface profiles. It has been postulated that online monitoring of surface finish quality can be used to provide feedback information for a secondary control loop for the machining process, which will lead to the production of consistently high quality surface finishes. There is an existing vision-based wood surface profile measurement technique, but the application of the technique has been limited to static wood samples. This thesis extends the application of the technique to moving wood samples. It is shown experimentally that the method is suitable for in-process surface profile measurements. The current industrial wood planing machines do not have the capability of measuring and adjusting process parameters in real-time. Therefore, knowledge of the causes of surface finish degradation would enable the operators to optimise the mechanical structure of the machines offline. For this reason, two novel approaches for characterising defects on planed timber surfaces have been created in this thesis using synthetic data. The output of this work is a software tool that can assist machine operators in inferring the causes of defects based on the waviness components of the workpiece surface finish. The main achievement in this research is the design of a new active wood planing technique that combines real-time cutter path optimisation (cutting tool inaccuracy compensation) with vibration disturbance rejection. The technique is based on real-time vertical displacements of the machine spindle. Simulation and experimental results obtained from a smart wood planing machine show significant improvements in the dynamic performance of the machine and the produced surface finish quality. Potential areas for future research include application of the defects characterisation techniques to real data and full integration of the dynamic surface profile measurements with the smart wood planing machine.

Machining is one of the most important operations in many industrial environments. To prosper in today's competitive industrial world any machining system should be able to deliver the highest possible quality at the lowest possible costs, with very high reliability and flexibility. To fulfil these requirements the idea of e-Monitoring an industrial process was introduced by the Intelligent Process Monitoring and Management (IPMM) Centre at Cardiff University. It has considerable potential applications in industrial systems to not only monitor the health of the machines but also for data management and presentation for future decision making. The research presented in this thesis considers the evolution of two different low complexity signal analysis techniques which can be used for e-Monitoring the health of the cutters used in milling machine tools. The researched techniques are based in the time and frequency domains. The frequency domain analysis technique is based on the idea of using switched capacitor filters and microcontrollers to monitor the frequencies of interest in existing machine tool signals (spindle load and speed) thus avoiding the need for external sensors. The results of frequency domain analysis are used to assess the health of the cutter. The time domain analysis technique uses the same signals to analyse any variations within a tool rotation period and relate these to the health of the cutter. The results are integrated before final decision making which helps in reducing false alarms. The thesis goes on to logically describe the design and development of an on-line microcontroller based distributed intelligent e-Monitoring system for a milling machine tool model Kondia B500, using the proposed signal analysis techniques. Some additional features such as internet and GSM connectivity have also been added to the designed system. The designed system was interfaced to the machine tool and tested for its reliability which was found to be competitive with many other very expensive systems. The designed system can be fitted into a machine tool at the manufacturing stage or it could be interfaced to an existing machine tool for automatically detecting a tooth breakage.