Thesis (PhD (Industrial Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: Injection moulding of polymer components is subject to ever increasing demands for improved
part quality and production rate. It is widely recognised that the mould cooling strategy employed
is crucial to achieving these goals. A brief overview of injection moulding units and different types
of injection moulds is given.
The modern Additive Manufacturing (AM) technology for processing metal powders such as
Direct Metal Laser Sintering (DMLS) and Selective Laser Melting (SLM) offers almost full
freedom to the mould designer. Some of these modern manufacturing methods based on metal
powders, which are able to produce complex cooling channels are analysed.
A drastic change has entered the mould design domain - shifting the paradigm from design for
manufacture to manufacture for design. In combination with suitable AM methods the concept of
surface cooling moulds can now be efficiently implemented.
This study presents a new approach of predicting the minimum cooling time required for the
produced part. Different cooling layouts are analysed taking the heat transfer into consideration.
The lumped heat capacity method is implemented in this research in order to determine the
minimum cooling cycle time required.
A new approach was developed to determine the most suitable cooling layout configuration, such
as conventional cooling, conformal cooling or surface cooling, required for a moulded part based
on its characteristics such as shape complexity, space available for the cooling layout, part
quality requirements, production volume, and product life cycle.
A mould cooling design process including simulation, reverse engineering and manufacturing of
the mould insert was implemented in this study.
In order to validate the generic model developed during the course of this research comparative
experiments were carried out to determine the difference in performance of injection moulding
using conventional or surface cooling methods. The experimental results showed a significant
improvement in part quality produced with reduced cycle times using the surface cooling method. / AFRIKAANSE OPSOMMING: ‘Injection Moulding’ van polimeer komponente word al meer gedruk vir verbeterde kwaliteit en
vinniger produksie tyd. Dit is orals bekend dat die gietvorm afkoeling strategie ‘n groot rol speel
om hierdie twee doelwitte te bereik. Eers word ‘n kort oorslag gegee van ‘Injection Moulding’
eenhede en van verskillende ‘Injection Moulding’ vorms.
Die moderne Aditatiewe Vervaardigingstegnologie vir die prosessering van metaal poeiers soos
bv. Direkte Metaal Laser Sintering (DMLS) en Selektiewe Laser Smelting (SLM) bied basies volle
vryheid ten opsigte van gietvorm ontwerp. Party van die moderne vervaadigings metodes, wat op
metaal poeiers gebaseer is, wat komplekse koelings kanale kan produseer word geanaliseer.
Die ontwerpers arena het ‘n groot verandering ondergaan deurdat die fokus van ontwerp vir
vervaardiging verskuif het na vervaardiging vir ontwerp. In kombinasie met toepaslike aditatiewe
vervaardigings metodes kan oppervlak verkoeling nou effektief geïmplementeer word.
Hierdie studie bied a nuwe manier om die minimum verkoelings tyd benodig vir ‘n part te
voorspel. Verskeie verkoelings uitlegte word geanaliseer waar hitte oordrag in ag geneem word.
Die “lumped heat capacity” metode word gebruik om die minimum siklus tyd te bepaal.
‘n Nuwe benadering is ontwikkel om die mees geskikste verkoelings uitleg soos bv.
konvensionele verkoeling, konvorme verkoeling of oppervlak verkoeling te bepaal vir ‘n spesifieke
part gebaseer op die part se vorm kompleksiteit, spasie beskikbaar vir verkoelings kanale,
kwaliteit vereistes en produk lewensiklus.
Die volgende is in die studie geïmplementeer: ‘n vorm verkoelings ontwerp proses met simulasie,
‘reverse engineering’ en vervaardiging van die vorm insetsel.
Om die generiese model te verifieer gedurende die studie is vergelykende eksperimente
uitgevoer om die verskil in prestasie te bepaal tussen die gebruik van konvensionele en
oppervlak verkoelings metodes. Die eksperimentele resultate het ‘n beduidende verbetering in
part kwaliteit getoon met ‘n verkorte siklus tyd tydens die gebruik van die oppervlag verkoelings
metode.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/6652 |
| Date | 03 1900 |
| Creators | Moammer, A. A. |
| Contributors | Dimitrov, D. M., Harms, T. M., Van der Merwe, A. F., University of Stellenbosch. Faculty of Engineering. Dept. of Industrial Engineering. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 153 p. : ill. |
| Rights | University of Stellenbosch |
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