Browsing by Author "Uheida, E. H."

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    Investigating the impact of tool velocity on the process conditions in incremental forming of titanium sheets
    (Elsevier, 2017) Uheida, E. H.; Oosthuizen, G. A.; Dimitrov, D.
    ENGLISH ABSTRACT: This paper deals with a study focused on the single point incremental forming (SPIF) of titanium Grade 2 sheets. The direct impact of the sliding velocity of the forming tool on mechanical and thermal process loads was experimentally investigated. A wide range of spindle speeds and feed rates were examined at different forming conditions. The developed profiles of the mechanical and thermal demands during the SPIF of titanium sheets are presented and discussed. Forming temperature and force were directly related to the tool rotation speed, higher temperatures and lower reactional forces correspond to higher speeds. At very high rotation, failure conditions occurred and the ability to shape a CP Grade 2 sheet is decreased; these failures were mainly due to extreme heating, leading to termination of the tests concerned. The main objective of the study is to gain a better understanding of the combined effects that the varied relative motions at the tool/sheet contact zone have on the process conditions.
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    Resource efficient process chain development of a modular CubeSat spaceframe
    (Elsevier, 2019) Oberholzer, J. F.; Uheida, E. H.; Oosthuizen, G. A.
    ENGLISH ABSTRACT: A CubeSat is a 10×10×10 cm cube that can weigh up to 1.33 kg. This design offers a less expensive alternative for space enthusiasts to explore the cosmos, even though the total weight is very limited. For a CubeSat to be allowed to launch, it must adhere to certain specifications outlined in the CubeSat Design Specifications document. This places several restrictions on the satellite in terms of weight, size and center of gravity, and innovative solutions need to be explored during integration to meet these specifications. Having a spaceframe that can easily be assembled and disassembled will help smooth out the integration stage and save a significant time that can then be allocated elsewhere in the developmental stages. The increasing relevance of resource efficient manufacturing is prevalent through the continually rising costs of resources and energy. In order to stay competitive, manufacturers must develop resource efficient process chains to gain an advantage in the market. This study focused on developing a resource efficient process chain to manufacture a modular CubeSat spaceframe. This spaceframe must adhere to the CubeSat Design specifications, as well as meet the customer’s needs. A unique assembly process was designed that eliminated the need for screws structure together. Instead the spaceframe relies on interference fits, and utilizes the unique deployment method of the Poly-Picosatellite Orbital Deployer to ensure that the assembly does not fail. A material selection procedure was utilized, along with resource efficient manufacturing process chains to develop a CubeSat structure that is very cost effective to produce, easily assembled and disassembled and weighed less than most of the market leading CubeSat structures.
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    Toward understanding the process limits of incremental sheet forming of titanium alloys
    (Faculty of Engineering, Department of Industrial Engineering, Stellenbosch University, 2016) Uheida, E. H.; Oosthuizen, G. A.; Dimitrov, D.
    Incremental sheet forming (ISF) process is characterised by high flexibility at low cost, and short replacement time. ISF as a process has received global attention. Particular areas include the aerospace industries, customized products for biomedical applications and prototyping in the automotive industry. Most applications can become competitive due to the flexibility offered by this manufacturing process. In this work, a background study and review of state-of-the-art ISF have been undertaken with the aim of providing a better understanding of the process limitations. The critical factors of incremental sheet forming were discussed and the mechanical and thermal process demands were identified. This information provides the foundation for developing a forming optimisation map.