Browsing by Author "Conradie, Pieter"

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    Die struktuur van die liefde : 'n tipering van die wese van die liefde met verwysing na die betekenis van bepaalde antropologiese benaderings in die beskrywing van hierdie fenomeen
    (Stellenbosch : Stellenbosch University, 1958) Conradie, Pieter; Stellenbosch University. Faculty of . Dept. of .
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    The effect of cutting parameters on surface integrity in milling TI6AL4V
    (Southern African Institute for Industrial Engineering, 2016) Oosthuizen, Tiaan; Nunco, Keshav; Conradie, Pieter; Dimitrov, Dimitri
    The objective of machining performance is to reduce operational costs and to increase the production rate while maintaining or improving the required surface integrity of the machined component. Together with industrial partners, several benchmark titanium components were selected and machined to achieve this. Titanium alloys are used extensively in several industries due to its unique strength-to-weight ratio and corrosion resistance. Its properties, however, also make it susceptible to surface integrity damage during machining operations. The research objectives of this study were to understand the effect of cutting parameters on surface integrity to ensure that machined components are within the required surface quality tolerances. The effect of cutting speed and feed rate on surface roughness, micro-hardness, and the microstructure of the work piece were studied for milling Ti6Al4V. The surface roughness increased with a greater feed rate and a decrease in cutting speed. The maximum micro-hardness was 23 per cent harder than the bulk material. Plastic deformation and grain rotation below the machined surface were found with the rotation of the grain lines in the direction of feed. There was no evidence of subsurface defects for any of the cutting conditions tested.
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    Effect of milling strategy and tool geometry on machining cost when cutting titanium alloys
    (SAIIE, 2015) Conradie, Pieter; Oosthuizen, Tiaan; Dimitrov, Dimitri; Saxe, Mike
    The growing demands on aerospace manufacturers to cut more difficult-to-machine materials at increasing material removal rates require that manufacturers enhance their machining capability. This requires a better understanding of the effects of milling strategies and tool geometries on cutting performance. Ti6Al4V is the most widely-used titanium alloy in the aerospace industry, due to its unique combination of properties. These properties also make the alloy very challenging to machine. Complex aerospace geometries necessitate large material removal, and are therefore generally associated with high manufacturing costs. To investigate the effect of milling strategy and tool geometry on cutting performance, the new constant engagement milling strategy was firstly compared with a conventional approach. Thereafter, a component was milled with different cutting tool geometries. Cost savings of more than 40% were realised by using a constant engagement angle milling strategy. A reduction of 38% in machining time was achieved by using tools with a land on the rake side of the cutting edge. These incremental improvements made it possible to enhance the overall performance of the cutting process.
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    Investigating components affecting the resource efficiency of incorporating metal additive manufacturing in process chains
    (Elsevier, 2017) Girdwood, Richard; Bezuidenhout, Martin; Hugo, Philip; Conradie, Pieter; Oosthuizen, Gert; Dimitrov, Dimiter
    ENGLISH ABSTRACT: Pursuing more sustainable process chains, manufacturers are constantly striving to enhance the resource efficiency of their manufacturing processes. As part of this, additive technologies have become increasingly important for reducing waste, time and costs. Various input factors affect the efficiency of an additive approach and therefore also have an impact on the sustainability. Towards the establishment of an evaluation framework, this paper investigates the components that influence the resource efficiency of additive process chains. An overview is provided on the different approaches and techniques that have been used with the aim of identifying the most influential factors. The framework was validated using a titanium aerospace benchmark component and thereby proved its ability to assist the process planners with decisions regarding process chain selection.