Browsing by Author "Uheida, Emad Harari A."
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- ItemDevelopment and optimisation of incremental sheet forming of titanium grade 2: process mapping(Stellenbosch : Stellenbosch University, 2017-03) Uheida, Emad Harari A.; Oosthuizen, Gert Adriaan; Stellenbosch University. Faculty of Engineering. Dept. of Industrial Engineering.ENGLISH ABSTRACT: Manufacturing products ensure value creation from natural resources. The change in manufacturing systems to a greater emphasis on personalisation, increase the need for customised products. Manufacturing challenges are presented by the increasing instability in global markets, shorter innovation cycles, input cost pressures and generally expensive resources. Ever since the industrial revolution, the transformations in manufacturing from mass production and product variety and vice versa, were driven by market and societal transformations and the development of new enabling technologies. Single point incremental forming is a promising rapid prototyping technology for sheet metal applications. Titanium alloys are an attractive material for numerous applications, but its use has been mainly restricted by its material and manufacturing costs. Titanium alloys are also used in a variety of engineering applications, due to its high-strength to weight ratio, corrosion resistance and bio-compatibility. The alloy’s mechanical characteristics make it possible to reduce the application’s structural weight and increase its performance with thin-wall designs. Incremental sheet forming is characterised by its highly-localised deformation ability without drawing in material from a surrounding area. In this truly die-less configuration the sheet is shaped only by the action of a forming tool that has a single point of contact with the blank. Significant cost reductions can be realised from these flexible technologies devoted to reduce the buy-to-fly ratio and enlarge the scope of applications to small series titanium products. Although single point incremental sheet forming (SPIF) is an active research area, the process demands and limitations for forming of CP Grade 2 titanium alloy sheets are not clearly understood. Understanding the effects of these process variables to develop resource-efficient forming process chains of CP Grade 2 titanium sheets will make a significant contribution to manufacturing knowledge. In this dissertation, an efficient twostage process mapping approach is developed and validated. In order to characterise the SPIF conceptual processing space and to identify the key design factors, a systematic quantitative literature review has been undertaken analysing results from relevant publications. The design of experiments (DoE) and one factor at a time test (OFAT) experiments have been methodically implemented to verify the developed conceptual framework. The ultimate goal is to design aprocess suitable for incremental forming of CP Grade 2 sheets that can consistently deliver a product that meets the required quality attributes. The established approach involves mapping the SPIF of the CP Grade 2 in terms of the five key process variables. Once the behaviour of the SPIF process has been mapped, a thorough study of the role of a secondary process variable can be accomplished to evaluate its effect on the process across the full five-key-variables working window. The influence of SPIF factors on the formability of CP Grade 2 were investigated based on the forming forces, the forming temperature and the process productivity. The approach yields insight into the theory of the SPIF process, which deepens the understanding of the dependence of the process outcomes on different variables. The region of the SPIF process variable space, where successful forming of the CP Grade 2 titanium can be anticipated is identified throughout this process mapping approach. The processed data have been presented in a practical two-dimensional process map. The developed working window can be used as a design tool to understand the process demands and limitations for forming of CP Grade 2 titanium alloy sheets. This understanding of the effects of these process variables will enable the development of resource-efficient forming process chains for the CP Grade 2 titanium sheets. The approach as such, however, can be implemented for the establishing of process characteristics for other titanium alloys too.