Burrs are rough protrusions that form along the edge of a component during processing and are commonly produced during machining. Generally, the presence and severity of a burr directly impacts the final part quality. Thus, burrs need to be removed in subsequent processes to avoid injury when handling a part and/or negatively impacting the part's functionality. The size, shape, and nature of the attachment of the burr to the cutting edge are highly dependent on the material, tooling, and process parameters used during machining. This research aimed to develop two new approaches to minimize and/or eliminate burr formation during the drilling of ductile materials. The first new method outlined in this thesis relates to injecting materials in different forms at high pressures under the workpiece on the side from which the drilling tool exits to support the drilling thrust force and thereby minimize exit burr formation. The second method introduced a novel technique for designing and testing highly effective step drills based on the workpiece material and cutting parameters, using commercial drills. Testing the two approaches showed promising results for producing comparatively smaller exit burrs. / Thesis / Master of Applied Science (MASc)

The thesis contains theoretical analysis of drilling by twist drill focused on the step drill. The review includes description of the drill geometry, calculation of the basic parameters of drilling, including forces and process optimization. Following is manufacturing process and analysis of the monolithic step drill designed for the required hole parameters. The optimal cutting conditions are necessary to find for the correct function of the tool. The load values of the tool are accurately assessed using a piezoelectric dynamometer, thereby obtaining the overall progress of individual loads. The roughness of the workpiece is evaluated by the optical measuring device.