Friction stir welding of thin section aluminium extrusions for marine applications
- Authors: Chikamhi, Prince Philhelene
- Date: 2020
- Subjects: Friction welding , Welding
- Language: English
- Type: Thesis , Masters , MEng
- Identifier: http://hdl.handle.net/10948/46030 , vital:39410
- Description: This dissertation focuses on the development of a welding extrusion feeder, tool and schedule for implementation of defect-free butt welds on long, thin and complex-shape aluminium extrusions, as used by the marine industry. Viability of employing Friction Stir Welding (FSW) as a welding technology for joining long extrusions with a short-bed and bolt-on feeder to facilitate onsite fabrication of flat structures in shipbuilding is evaluated. An FSW feeder, tool and process control unit were designed, developed and integrated with an existing FSW platform, to facilitate implementation of continuous welds. Weld data acquired from literature review, experimentation, mechanical testing and metallographic analysis was used in design considerations for the development of a feeder. Subsequently, butt welds were implemented successfully on long 3 mm AA6082-T6 extrusions, during continuous FSW on the feeder. A specially adapted tool, the Floating Bobbin Tool, used with the feeder to implement butt welds was designed and developed from literature tool heuristics and weld trials. The tool eliminated the need for a backing bar and enabled tool-workpiece auto-alignment, beneficial with thin-section extrusions. Effect of rotational and weld speed and tool geometry of two tools (Tool 1 and 2), on weld forces and quality was tested, to establish optimum parameters for attaining high quality welds. Tool geometry had a profound effect on weld forces and integrity; Tool 2 welds exhibited superior and consistent weld quality, meeting maritime rules and standards and proving the adequacy of using FSW for joining long thin extrusions. Feeder process control, automation and optimisation, was implemented by process control unit devices, in addition to force and position control provided by the existing FSW platform. Owing to process control, automation and optimisation during continuous FSW of thin long and complex-shape aluminium extrusions, welding setup times and process variations are minimised and chances for defect-free welds increased, boosting production and cost savings in large panel fabrication in shipbuilding.
- Full Text:
- Date Issued: 2020
- Authors: Chikamhi, Prince Philhelene
- Date: 2020
- Subjects: Friction welding , Welding
- Language: English
- Type: Thesis , Masters , MEng
- Identifier: http://hdl.handle.net/10948/46030 , vital:39410
- Description: This dissertation focuses on the development of a welding extrusion feeder, tool and schedule for implementation of defect-free butt welds on long, thin and complex-shape aluminium extrusions, as used by the marine industry. Viability of employing Friction Stir Welding (FSW) as a welding technology for joining long extrusions with a short-bed and bolt-on feeder to facilitate onsite fabrication of flat structures in shipbuilding is evaluated. An FSW feeder, tool and process control unit were designed, developed and integrated with an existing FSW platform, to facilitate implementation of continuous welds. Weld data acquired from literature review, experimentation, mechanical testing and metallographic analysis was used in design considerations for the development of a feeder. Subsequently, butt welds were implemented successfully on long 3 mm AA6082-T6 extrusions, during continuous FSW on the feeder. A specially adapted tool, the Floating Bobbin Tool, used with the feeder to implement butt welds was designed and developed from literature tool heuristics and weld trials. The tool eliminated the need for a backing bar and enabled tool-workpiece auto-alignment, beneficial with thin-section extrusions. Effect of rotational and weld speed and tool geometry of two tools (Tool 1 and 2), on weld forces and quality was tested, to establish optimum parameters for attaining high quality welds. Tool geometry had a profound effect on weld forces and integrity; Tool 2 welds exhibited superior and consistent weld quality, meeting maritime rules and standards and proving the adequacy of using FSW for joining long thin extrusions. Feeder process control, automation and optimisation, was implemented by process control unit devices, in addition to force and position control provided by the existing FSW platform. Owing to process control, automation and optimisation during continuous FSW of thin long and complex-shape aluminium extrusions, welding setup times and process variations are minimised and chances for defect-free welds increased, boosting production and cost savings in large panel fabrication in shipbuilding.
- Full Text:
- Date Issued: 2020
The relationship between employee value proposition, organisational commitment and intention-to-serve among provincial traffic officers
- Authors: Macpherson, Wayne Elvison
- Date: 2017
- Subjects: Organizational commitment -- South Africa -- Eastern Cape Organizational behavior -- South Africa -- Eastern Cape , Employee motivation -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/18036 , vital:28567
- Description: Traffic officers are employed to protect and serve the community, but various sources including annual reports and newspaper articles cast doubt on whether these goals are attained in the Eastern Cape. These sources further allege that the failure to serve can be attributed to dissatisfaction and poor employee commitment. Therefore, the main objective of this study was to explore the relationship between the Employee Value Proposition, organisational commitment and intention-to-serve among provincial traffic officers. A literature study was conducted on the three above-mentioned variables to achieve this objective. The empirical study consisted of a survey with a self-administered questionnaire. Five components of the Employee Value Proposition, as established by the Corporate Leadership Council (CLC) (2006), were measured. These included career opportunities, organisation itself, relationships, remuneration/reward and work itself. The Three Component Model (TCM) developed by Meyer and Allen (1991) was used to measure affective, continuance and normative commitment. The Intention-to-Serve Scale was adapted from the Employee Work Passion Appraisal (EWPA) Model (Zigarmi, Nimon, Houson, Witt and Diehl, 2011) and was used to measure intent-to-perform and intent-to-use discretion. The questionnaire was completed by 357 provincial traffic officers across the six districts of the Eastern Cape, which represented a 95 percent response rate. The results from the empirical study indicated that the majority of respondents had less positive perceptions of the Employee Value Proposition offered to them. Affective commitment, regarded as the desired type of organisational commitment, was scored the lowest. However, positive scores were obtained for intention-to-serve. A statistical and practical significant relationship was found between the Employee Value Proposition and organisational commitment, and between the Employee Value Proposition and intention-to-serve as well as between organizational commitment and intention-to-serve. The results suggest that a more appealing Employee Value Proposition could result in improved organisational commitment as well as improved intention-to-serve. It is therefore recommended that the Eastern Cape Department of Transport reconsider the Employee Value Proposition offered to traffic officers and use it as a tool to improve commitment and service delivery.
- Full Text:
- Date Issued: 2017
- Authors: Macpherson, Wayne Elvison
- Date: 2017
- Subjects: Organizational commitment -- South Africa -- Eastern Cape Organizational behavior -- South Africa -- Eastern Cape , Employee motivation -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/18036 , vital:28567
- Description: Traffic officers are employed to protect and serve the community, but various sources including annual reports and newspaper articles cast doubt on whether these goals are attained in the Eastern Cape. These sources further allege that the failure to serve can be attributed to dissatisfaction and poor employee commitment. Therefore, the main objective of this study was to explore the relationship between the Employee Value Proposition, organisational commitment and intention-to-serve among provincial traffic officers. A literature study was conducted on the three above-mentioned variables to achieve this objective. The empirical study consisted of a survey with a self-administered questionnaire. Five components of the Employee Value Proposition, as established by the Corporate Leadership Council (CLC) (2006), were measured. These included career opportunities, organisation itself, relationships, remuneration/reward and work itself. The Three Component Model (TCM) developed by Meyer and Allen (1991) was used to measure affective, continuance and normative commitment. The Intention-to-Serve Scale was adapted from the Employee Work Passion Appraisal (EWPA) Model (Zigarmi, Nimon, Houson, Witt and Diehl, 2011) and was used to measure intent-to-perform and intent-to-use discretion. The questionnaire was completed by 357 provincial traffic officers across the six districts of the Eastern Cape, which represented a 95 percent response rate. The results from the empirical study indicated that the majority of respondents had less positive perceptions of the Employee Value Proposition offered to them. Affective commitment, regarded as the desired type of organisational commitment, was scored the lowest. However, positive scores were obtained for intention-to-serve. A statistical and practical significant relationship was found between the Employee Value Proposition and organisational commitment, and between the Employee Value Proposition and intention-to-serve as well as between organizational commitment and intention-to-serve. The results suggest that a more appealing Employee Value Proposition could result in improved organisational commitment as well as improved intention-to-serve. It is therefore recommended that the Eastern Cape Department of Transport reconsider the Employee Value Proposition offered to traffic officers and use it as a tool to improve commitment and service delivery.
- Full Text:
- Date Issued: 2017
Valuing preferences for freshwater inflows into the Bira, Bushmans, Kasouga, Keiskamma, Kleinemond East, Nahoon and Tyolomnqa estuaries
- Authors: Van der Westhuizen, Henri
- Date: 2007
- Subjects: Estuarine ecology -- South Africa -- Eastern Cape , Freshwater ecology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:8998 , http://hdl.handle.net/10948/628 , Estuarine ecology -- South Africa -- Eastern Cape , Freshwater ecology -- South Africa -- Eastern Cape
- Description: There are about 259 estuaries in South Africa that can be classified as “functioning” and their “health” status is directly related to the quantity and quality of freshwater that flows into them. Many of South Africa’s estuaries have become smaller due to a steady decrease in the amount of freshwater that flows into them. This reduction in freshwater inflows decreases their ecological functioning and undermines the recreational activities and subsistence services available from them. The National Water Act (ACT No. 36 of 1998) recognises the right of the environment to water, but a large amount of data is still needed to make management decisions on the allocation of freshwater. The objective of this research was to contribute to the management of the allocation of freshwater in the catchment areas of the Bira, Bushmans, Kasouga, Keiskamma, Kleinemond East, Nahoon and Tyolomnqa rivers by determining the recreational value of the freshwater flowing into their estuaries. This recreational value was established using the contingent valuation method. The contingent valuation method (CVM) is a technique to establish the value of a good (or service) that is not bought or sold in an actual market. This technique is frequently applied in the valuation of environmental goods, e.g. the freshwater that flows into an estuary. The CVM establishes the economic value by asking the users of an environmental good to state their willingness to pay (WTP) for a hypothetical project to prevent or bring about a change in the current condition of the environmental good. The users’ WTP is then aggregated to establish a total willingness to pay (TWTP) for the population of the users of the environmental good. The hypothetical project presented in this study is that of an increase of freshwater inflows, that would prevent (bring about) predetermined changes in environmental services provided by the selected seven estuaries.
- Full Text:
- Date Issued: 2007
- Authors: Van der Westhuizen, Henri
- Date: 2007
- Subjects: Estuarine ecology -- South Africa -- Eastern Cape , Freshwater ecology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:8998 , http://hdl.handle.net/10948/628 , Estuarine ecology -- South Africa -- Eastern Cape , Freshwater ecology -- South Africa -- Eastern Cape
- Description: There are about 259 estuaries in South Africa that can be classified as “functioning” and their “health” status is directly related to the quantity and quality of freshwater that flows into them. Many of South Africa’s estuaries have become smaller due to a steady decrease in the amount of freshwater that flows into them. This reduction in freshwater inflows decreases their ecological functioning and undermines the recreational activities and subsistence services available from them. The National Water Act (ACT No. 36 of 1998) recognises the right of the environment to water, but a large amount of data is still needed to make management decisions on the allocation of freshwater. The objective of this research was to contribute to the management of the allocation of freshwater in the catchment areas of the Bira, Bushmans, Kasouga, Keiskamma, Kleinemond East, Nahoon and Tyolomnqa rivers by determining the recreational value of the freshwater flowing into their estuaries. This recreational value was established using the contingent valuation method. The contingent valuation method (CVM) is a technique to establish the value of a good (or service) that is not bought or sold in an actual market. This technique is frequently applied in the valuation of environmental goods, e.g. the freshwater that flows into an estuary. The CVM establishes the economic value by asking the users of an environmental good to state their willingness to pay (WTP) for a hypothetical project to prevent or bring about a change in the current condition of the environmental good. The users’ WTP is then aggregated to establish a total willingness to pay (TWTP) for the population of the users of the environmental good. The hypothetical project presented in this study is that of an increase of freshwater inflows, that would prevent (bring about) predetermined changes in environmental services provided by the selected seven estuaries.
- Full Text:
- Date Issued: 2007
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