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Abstract
A comprehensive literature review on the development of AJM technology and the associated sciences has been conducted and presented. Although AJM is a promising technology for micromachining, it has been found that most studies in this field have been oriented towards high-pressure abrasive waterjet (AWJ) cutting, while little attention has been paid to micromachining using low-pressure jets with air as the jet fluid. The work in this thesis is aimed to address some of the issues identified with a specific objective of gaining a further and deeper understanding of the machining process and process performance and developing machining performance models for micro-grooving with low pressure abrasive air jets.
An experimental study on the abrasive jet micromachining process using low-pressure air jets has been carried out to understand the relationship between the process parameters (i.e. nozzle diameter, air pressure, abrasive mass flowrate, jet impact angle, nozzle traverse speed) and major cutting performance measures (i.e. groove depth and width, kerf taper angle and roughness of the groove bottom surface). It has been found that increasing the air pressure increases the groove depth and width and decreases the kerf taper angle, while abrasive mass flowrate does not have a significant effect on the groove depth and width and the surface roughness. In addition, it is revealed that the maximum jet penetration occurs at near orthogonal jet impact angles. The effects of the process parameters on the various major cutting performance measures have thus been amply studied with the significance of each parameter identified by a statistical analysis. Recommendations are then made for the selection of process variables for micromachining of quartz crystals.
Predictive models for the major cutting performance measures, which are essential for the optimisation of the micromachining process, are developed based on dimensional and statistical analysis. The developed models relate the major performance measures to the process parameters in abrasive micro-jet grooving, and have been verified by comparing their predictions with the data from a separate experiment. The assessments of the predicted models show that the developed models have been correctly formulated and can give adequate prediction of the cutting performance.