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Doctor of Philosophy / This research aimed to develop new cooling methods to replace, or at least minimise, the use of currently used grinding coolants which are known to be harmful to the environment. The methods used involved the application of a cold air and vegetable oil mist mixture (CAOM), and the use of liquid nitrogen as cooling media. Allied research focused on the development of a segmented grinding wheel equipped with a coolant chamber. The feasibility of a grinding system using CAOM was assessed on the surface grinding of plain carbon steel 1045. It was found that at low material removal rates, ground surfaces were obtained with a quality comparable to that from grinding with a conventional coolant in association with a reduction of grinding forces. There was no significant difference in the subsurface hardness of the components using CAOM, although the latter method showed a stronger dependence of surface residual stresses on the depth of cut due to the limit in cooling capacity of CAOM. The effects of using liquid nitrogen as a cooling medium on the microstructure of quenchable steel were explored. It was found that a martensite layer was induced on the ground surface. The microstructure featured a dispersion of very fine carbides within the martensite lattice, resulting in a remarkable increase in hardness and high compressive residual stresses within the layer. The topography of the ground surfaces indicated that the material was predominantly removed by brittle fracture. Furthermore surface oxidisation was suppressed. In the interest of coolant minimisation, a segmented wheel equipped with a pressurized coolant chamber was developed. A higher quality ground surface was obtained in conjunction with a coolant saving of up to 70%. In addition, the adhesion of ground chips on the wheel surface largely disappeared. Furthermore, surface tensile residual stresses caused by thermal deformation were minimised. The mechanism of coolant disintegration to form mists using this type of wheel system was studied. The Weber theory for Newtonian jet instability was applied to quantitatively determine the contribution of coolant flow rate to mist and ligament modes. A semi-analytical model was then developed to predict the mist flow rate by taking into account both grinding parameters and coolant properties. The model prediction was in agreement with experimental measurements. Based on the principles of fluid motion and the mechanisms of spin-off and splash, analytical models for both conventional and segmented wheels were established to provide a physical understanding of the mechanisms of coolant penetration into the grinding zone. Coolant minimisation was evident using the segmented wheel where the coolant pumping power into the grinding zone increased with wheel speed, but for the conventional wheel it decreased. A quantitative analysis was developed that accounted for the coolant properties and system design characteristics governing the penetration mechanism revealed by the theory established above. In conjunction with the mist formation analysis, the developed model offers a practical guideline for the optimal use of grinding coolants in achieving a balance between the demands of productivity and care for the environment.

In the past decade, ultrashort laser sources have had a decisive impact on material processing for photonic applications. The technique is usually restricted to the elemental association of an ultrashort source with a focusing lens. It is thus limited in the achievable bulk modifications. Accompanying studies of material modifications in space and time, we propose here that automated spatio-temporal tailoring of the laser pulses is an efficient manner to overcome these limitations. More precisely, we demonstrate the generation of multiple processing foci for synchronous photomachining of multiple devices in the bulk. Thus, we report on the parallel photowriting of waveguides, light couplers, light dividers in 2D/3D in fused silica glass. We show that the domain of photowriting can be extended to deep focusing. We indicate that this can be achieved by wavefront shaping or temporal profile tailoring conducted by an evolutionary optimization loop. We also have unveiled a singular interaction regime where regular structuring takes place before the focal region. For the first time, the dynamics of the energy coupling to the glassy matrix is evaluated for various temporal pulse profiles. Enhanced energy confinement in the case of picosecond pulses is confirmed by characterization of the transient electronic gas and of the subsequent pressure. These pump-probe studies were carried out with a self-build time-resolved microscopy system with temporally shaped pump irradiation. We also developed a new method based on the Drude model to differentiate the electronic and matrix contributions to the contrast of the microscopy images.

Particleboard (PB) is a widely used panel material because of its physical properties and low cost. Unfortunately, cutting can degrade its surface creating rejects and increasing manufacturing costs. A major challenge is PB’s internal variability. Different particle and glue bond strength combinations can sometimes create high quality surfaces in one area and defects such as edge chipping in nearby areas. This research examines methods of improving surface quality by examining PB characteristics and their interactions with the cutting tool. It also develops an analytical model and software tool that allows the effects of these factors to be simulated, thereby giving practical guidance and reducing the need for costly experiments. When PB is cut and the glue bond strength is weaker than the particle strength, particles are pulled out, leading to surface defects. When instead the glue bond strength is stronger than the particle strength, particles are smoothly cut, leading to a high quality surface. PB is modeled as a matrix of particles each with stochastically assigned material and glue bond strengths. The PB model is layered allowing particles to be misaligned. Voids are modeled as missing particles. PB cutting is modeled in three zones. In the finished material and tool tip zones, particles are compressed elastically and then crushed at constant stress. After failure, chip formation occurs in the chip formation zone. At large rake angles, the chip is modeled as a transversely loaded beam that can fail by cleavage at its base or tensile failure on its surface. At small rake angles, the chip is modeled as the resultant force acting on the plane from the tool tip through to the panel surface. Experimental and simulation results show that cutting forces increase with depth of cut, glue content and particle strength. They decrease with rake angle. Glue bond strength can be increased to the equivalent particle strength through the selection of particle geometry and the subsequent increased glue bond efficiency, which increases the cut surface quality without the need for additional glue. Minimizing the size and frequency of voids and using larger rake angles can also increase surface quality.

Additive Manufacture (AM) is a novel manufacturing method; it is a process of forming components by adding materials. Owing to material saving and manufacturing cost saving, more and more research has been focused on metal AM technologies. WAAM is one AM technology, using arc as the heat sources and wire as the material to create parts with weld beads on a layer-by-layer basis. The process can produce components in a wide range of materials, including aluminum, titanium and steel. High deposition rate, material saving and elimination of tooling cost are critical characteristics of the process. Cost estimation is important for all companies. The estimated results can be used as a datum to create a quote for customers or evaluate a quote from suppliers, an important consideration for the application of WAAM is its cost effectiveness compared with traditional manufacture methods. The aim of this research is to find a way to develop a cost estimating method capable of providing manufacturing cost comparison of WAAM with CNC. A cost estimation model for CNC machining has been developed. A process planning approach for WAAM was also defined as part of this research. An Excel calculation spreadsheet was also built and it can be easily used to estimate and compare manufacture cost of WAAM with CNC. Using the method developed in this research, the cost driver analysis of WAAM has been made. The result shows that reduced material cost is the biggest cost driver in WAAM. The cost comparison of WAAM and CNC also has been made and the results show that with the increase of buy-to-fly ratio WAAM is more economical than CNC machining.

There are several advantages to replacing CNC machinery with robotic machine tools and as such robotic machining is emerging into the manufacturing and metal cutting industry. There remain several disadvantages to using robots over CNC stations primarily due to flexibility in robotic manipulators, which severely reduces accuracy when operating under high machining forces. This flexibility is dependent on configuration and thus the configuration can be optimised through posture selection to minimise deflection. In previous work little has been done to account for operating frequency and the additional complications that can arise from frequency dependent responses of robotic machine tools. A Fanuc S-360 manipulator was used to experimentally investigate the benefits of including frequency compensation in posture selection. The robot dynamics first had to be identified and experimental modal analysis was selected due the inherent dependency on frequency characteristics. Specifically, a circle fit operation identified modal parameters and a least squares optimisation generated dynamic parameters for a spatial model. A rigid-link flexible-joint model was selected and a pseudo-joint was used to create an additional DOF to accommodate link flexibility. Posture optimisation was performed using a gradient-descent algorithm that used several starting points to identify a global minimum. The results showed that a subset of modal data that excluded the mode shape vectors could be used to create a model to predict the manipulator vibration response. It was also found that the receptance variation of the manipulator with configuration was insufficient to verify the optimisation throughout the entire selected workspace; however the model was shown to be useful in regions containing multiple peaks where the modelled dynamics were dominant over the highly volatile measured data. Simulations were performed on a redundant planar manipulator to overcome the lack of receptance variation found in the Fanuc manipulator. These simulations showed that there were two mechanisms driving the optimisation; overall amplitude reduction and frequency specific amplitude reduction. Using a stiffness posture measure for comparison, the results of the frequency specific reduction could be separated and were found to be particularly beneficial when operating close to resonant frequencies.

There are several advantages to replacing CNC machinery with robotic machine tools and as such robotic machining is emerging into the manufacturing and metal cutting industry. There remain several disadvantages to using robots over CNC stations primarily due to flexibility in robotic manipulators, which severely reduces accuracy when operating under high machining forces. This flexibility is dependent on configuration and thus the configuration can be optimised through posture selection to minimise deflection. In previous work little has been done to account for operating frequency and the additional complications that can arise from frequency dependent responses of robotic machine tools. A Fanuc S-360 manipulator was used to experimentally investigate the benefits of including frequency compensation in posture selection. The robot dynamics first had to be identified and experimental modal analysis was selected due the inherent dependency on frequency characteristics. Specifically, a circle fit operation identified modal parameters and a least squares optimisation generated dynamic parameters for a spatial model. A rigid-link flexible-joint model was selected and a pseudo-joint was used to create an additional DOF to accommodate link flexibility. Posture optimisation was performed using a gradient-descent algorithm that used several starting points to identify a global minimum. The results showed that a subset of modal data that excluded the mode shape vectors could be used to create a model to predict the manipulator vibration response. It was also found that the receptance variation of the manipulator with configuration was insufficient to verify the optimisation throughout the entire selected workspace; however the model was shown to be useful in regions containing multiple peaks where the modelled dynamics were dominant over the highly volatile measured data. Simulations were performed on a redundant planar manipulator to overcome the lack of receptance variation found in the Fanuc manipulator. These simulations showed that there were two mechanisms driving the optimisation; overall amplitude reduction and frequency specific amplitude reduction. Using a stiffness posture measure for comparison, the results of the frequency specific reduction could be separated and were found to be particularly beneficial when operating close to resonant frequencies.

The objective of this study is to develop a methodology to analyze the air quality and tool performance in turning process under near-dry condition. Near dry machining refers to the use of a very small amount of cutting fluid in the machining process. In order to implement the near dry machining technology, this dissertation develops the analytical models for both tool life and aerosol generation prediction. This research includes predictive models of cutting temperatures, cutting forces, tool wear progressions, and aerosol generation. The comparison of air quality and tool performance among dry machining process, near dry machining process, and flood cooling machining process is also presented. It is found that according to the selected cutting conditions in the model-based comparisons, the predicted cutting forces, cutting temperature and power consumption under near dry lubrication are reduced as high as about 30% compared with those in dry cutting but these predicted values are higher than those in wet cutting by about 10% under the same cutting conditions while the predicted tool wear land lengths are reduced by 60% compared with those in dry cutting but these values are higher than those in wet cutting about 1% under the same cutting conditions. However, the air quality for near dry machining with 12.5 ml/hr oil flow rate is worse than that for wet cutting due to different aerosol generation mechanisms.

A fixture is a critical link in a machining system. The majority of prior work treats the fixture-workpiece system as quasi-static and ignores the system dynamics. In addition, material removal effect (MRE) on fixture-workpiece dynamics is generally ignored. The primary goal of this thesis is to develop a model-based framework for analysis and synthesis of the fixturing dynamic stability of a machining fixture-workpiece system accounting for the MRE. Five major accomplishments of this thesis are summarized as follows: First, a systematic procedure for analysis of fixturing dynamic stability of an arbitrarily configured machining fixture-workpiece system is developed. Second, models and approaches developed in this work are experimentally validated. It is found that consideration of dynamics and characterization of system dynamic properties are crucial for an accurate analysis. Third, an in-depth investigation of the MRE on fixture-workpiece dynamics is performed. The results show that material removal can significantly change the system characteristics and behavior and approaches developed are capable of capturing the change. Fourth, roles of important fixture design and machining process parameters in affecting fixturing dynamic stability are studied and understood via a parameter effect analysis. Additionally, fixturing dynamic stability is found to be sensitive to the parameter imprecision. Finally, a generic approach for determination of minimum clamping forces that ensure fixturing dynamic stability is developed. Because of MRE, dynamic clamping is found to be an option to achieve the best possible system performance. Models and approaches developed in this thesis are generic and can be used as simulation tools in fixture design. Insights obtained from this research advance the knowledge base of machining fixtures and provide general fixture design guidelines.

In the study, the effects of the machining conditions, ex, machining positions, loads and rotating speed ratio on machining mechanism of wafer are investigated by using the continuous composite electroplated polisher and find the best machining conditions of the polisher. Experimental results show that when the wafer and polisher are full contact, the operating of machinery is most smooth and the flatness is better. When the load is increased, the reducing rate of average roughness¡]Ra¡^and maximum roughness¡]Rmax¡^, removal rate, and the speed of mirror degree are increased. The machining mechanism and the stability of machinery is depended on the value of rotating speed ratio. In the different rotating speed ratio, the flatness of wafer is difference. For example, the rotating speed ratio is 1, the flatness is 1.5 £gm/38 mm. The rotating speed ratio is 2, the flatness is 2.3 £gm/38 mm. Finally, choose the rotating speed ratio, which the values of rotating speed are close and complex on the range of rotating speed which machinery can be operating most stable in machining process. Because of the machining mechanism are similar and the grinding locus are finer. Hence, the flatness of wafer becomes better. When the rotating speed ratio is 1.1, the flatness is 1.46£gm/38 mm. The rotating speed ratio is 1.11, the flatness is 1.45£gm/38 mm. The effect of the rotating speed ratio of the wafer and polisher on the grinding locus type of grinding surface is theoretically analyzed. Results show that when the rotating speed ratio is irregular, the distribution of grinding locus becomes finer. The analyzable results of locus and provable results of experiment are the same.