| Summary: | Thesis (MScEng (Industrial Engineering))--University of Stellenbosch, 2008. === This thesis forms part of the AMTS Project on Investment Casting Capabilities for Light Metal Alloys in
South Africa, the focus area being Rapid Tooling Development.
Various issues of the investment casting process are being discussed from an industrial engineering
point of view. These issues are related to the possibilities of improving the investment casting process’
lead times by shortening it while still maintaining affordable costs and required quality. Hereby the
possibilities given by the newly developed “rapid technologies” are investigated.
The focus is on Rapid Pattern Making as one of the most essential components for accelerated
development of new products. Three of the most widely used layer manufacturing processes available
in South Africa are selected for the study, namely Three Dimensional Printing – Drop-on-Bed (ZCorporation),
Selective Laser Sintering (EOS) and Three Dimensional Printing – Drop-on-Drop
(ThermoJet - 3D Systems). These three methods represent different materials; therefore different
mechanical properties, different process economics as well as different technological characteristics.
A standard benchmark part is used as a study base. Four patterns are produced by these three
methods. A comprehensive measurement programme is conducted, followed by an appropriate
statistical analysis and evaluation regarding accuracy and surface finish.
Rapid Die Making is analysed with the possibilities of using additive methods for rapid tooling. Two dies
are built with the same technology – Selective Laser Sintering (EOS), but in different materials. The
same evaluation methodology is used for the statistical analysis and comparison.
The two dies are injected with wax in order to produce the original benchmark part. The best wax
patterns from each die are selected and evaluated, using the same methodology for analysis and
comparison.
The current state of Direct Shell Production is shortly discussed.
The research concludes that RP&T techniques can successfully be used for creating accurate patterns
and dies in order to shorten lead times in the investment casting process chain. Each RP&T process
has its own set of advantages and disadvantages. All users should evaluate their requirements and the
capabilities of the variety of techniques before deciding on a process to apply.
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