- Title
- Electrostatic discharge and roughness modelling in diamond turning of contact lenses
- Creator
- Kopi, Fundiswa
- Subject
- Diamond turning Contact lenses
- Date Issued
- 2017
- Date
- 2017
- Type
- Thesis
- Type
- Masters
- Type
- MEng
- Identifier
- http://hdl.handle.net/10948/18783
- Identifier
- vital:28723
- Description
- With the increased application of ultra-high precision machining of polymers and the limited research in single point diamond turning (SPDT) of contact lens polymers, it became imperative to gather understanding on the production of contact lenses using the above-mentioned technology. A limiting factor in SPDT of polymers is wear of the diamond tool, resulting into poor surface finish due to unintended charges generated as a result of the contact/rubbing action between the cutting tool and the cut material. Central Composite Design (CCD) Face Centred experimental design was developed and applied to the SPDT of ONSI-56 and Polymethly methacrylate (PMMA) contact lens buttons. An electrostatic sensor coupled to a computer monitored the electrostatic discharge generated and a profilometer measured the surface roughness. The Response Surface Method (RSM) was utilised during the development of predictive models for both the surface roughness and the electrostatic discharge generated, to deduce the effects of cutting parameters during machining. The cutting speed and the feed rate deemed as the influential parameters on the surface roughness and electrostatic discharge, for both materials. The depth of cut induced more charge generation for PMMA. Predictive models were successfully developed and they were aimed at creating a database a guide to the SPDT of contact lens polymers.
- Format
- xv, 169 leaves
- Format
- Publisher
- Nelson Mandela Metropolitan University
- Publisher
- Faculty of Science
- Language
- English
- Rights
- Nelson Mandela Metropolitan University
- Hits: 410
- Visitors: 452
- Downloads: 68
Collections
NMU School of Engineering
| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | SOURCE1 | Electrostatic Discharge and Roughness Modelling in Diamond Turning of Contact Lenses | 3 MB | Adobe Acrobat PDF | View Details Download |