The edge rounding of brittle materials by vibratory finishing, VF, was investigated. Borosilicate glass and silicon nitride specimens were processed in two typical VF setups. In all cases, the processed specimens exhibited wear and chipping at their edges, whereas their flat surfaces remained intact. Edge chipping was strongly affected by the edge geometry and process parameters such as the media size and vibration amplitude of the finisher. Therefore, to achieve smooth chip-less edge, samples were processed in several steps, starting with the least energetic conditions, followed by more energetic ones as the edge became progressively blunter. The analysis of edge wear by VF revealed a new mechanism of wear, not previously reported in the literature. A stochastic numerical model was subsequently developed to model this mechanism of wear. To confirm the validity of the model, the model predictions were compared to the experimental observations of wear in the vibratory finisher. The model was used to investigate the effect of various VF process parameters on the edge wear of brittle materials.
A VF simulator was used to investigate wear and chipping under more controlled conditions. The VF simulator launched particles against the specimens at adjustable velocities and impact angles. The effect of particles’ shape, and impact velocity and angle, on the wear of glass edges was investigated. Fundamental differences were observed between wear by abrasive and smooth particles. These differences were attributed to the mechanisms of material removal by abrasive
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and smooth balls. Abrasive balls remove material by the sharp indentation of their surface asperities, whereas smooth particles lack such sharp peaks and hence apply blunt indentation on the edges. To identify the fundamental differences between material removal by sharp and blunt indenters, a series of indentation experiments were carried out on glass edges. Subsequently, these differences were discussed in terms of their implications on wear by abrasive and smooth particles.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/29818 |
| Date | 31 August 2011 |
| Creators | Mohajerani, Amirhossein |
| Contributors | Spelt, Jan K. |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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