Development, evaluation, and selectionof rapid tooling process chains for sandcasting of functional prototypesD Dimitrov1*, W van Wijck1, N de Beer1, and J Dietrich2

1Department of Industrial Engineering, University of Stellenbosch, Matieland, South Africa2Department of Manufacturing Engineering, University of Applied Sciences, Dresden, Germany

The manuscript was received on 6 September 2006 and was accepted after revision for publication on 16 May 2007.

DOI: 10.1243/09544054JEM728

Abstract: This paper discusses the results obtained from studies on different rapid toolingprocess chains for improved design and manufacture of foundry equipment for sand cast-ing of prototypes in final material for functional and pre-production tests of vehicles, usingthe three-dimensional printing process as core technology. Subsequently, while consider-ing aspects such as time, cost, quality (accuracy and surface roughness), and tool life, aframework for evaluation and selection of the most suitable process chain in accordance tospecific requirements is presented. Apart from only using these process chains for prototypemanufacturing, initial results from a study to apply one of these process chains in automatedsand casting full production is also presented. This research builds on an in-depth char-acterization of the accuracy and repeatability of a three-dimensional printing process.

Keywords: rapid tooling (RT), three-dimensional printing, casting

1 INTRODUCTION

The research in rapid tooling (RT) seems to be drivenby a demand for flexible manufacturing systems andsmaller production runs [1]. A large portion of thisresearch focuses on the utilization of selective lasersintering (SLS) as a key rapid prototyping (RP) pro-cess in the development of the tooling, with directsintering of metals playing an ever more significantrole [24]. In these examples the researchers aim atproducing parts in end-use materials and batch sizesin the order of several thousand. However, there isoften a need to manufacture a limited amount ofparts (typically less than 100) for design validation,proof of concept, pre-production tests (i.e. of vehi-cles), or for design check and approval of productiontooling. The most essential advantage hereby is theintegration of production planning and testing withinthe product development phase.

In recent years three-dimensional printing came tothe foreground as a very competitive process in termsof cost and speed, and sales of these machines haveincreased significantly compared to other RP equip-ment [5]. These devices were developed, and are stillseen, mostly as concept modellers. However, withthe relatively large number of available materialswith improved properties as well as the wide varietyof infiltrating agents and post-treatment procedures,the scope for this technology is expanding quickly far beyond the original idea of generating designiterations. Some of the earlier manufacturing appli-cations such as investment casting became trivial,some others such as sand casting opened new poten-tial [6, 7]. Depending on the needs, this technologyallows one to build a mould in sand straight fromthe computer-aided design (CAD) file or to fabricatecores and cavities in different materials. The nextchallenge is to develop optimized process chains tominimize lead times and production costs, while stillensuring a high quality of castings, with respect todifferent production scenarios related to:

(a) the size of production runs;(b) part size;

*Corresponding author: Department of Industrial Engineering,

University of Stellenbosch, c/o Banhoek and Joubert Street,

Stellenbosch 7600, Western Cape Province 7600, South Africa.

email: dimitrov@sun.ac.za

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