micromachines Review Application of Stereolithography Based 3D Printing Technology in Investment Casting Muslim Mukhtarkhanov, Asma Perveen and Didier Talamona * School of Engineering and Digital Sciences, Department of Mechanical and Aerospace Engineering, Nazarbayev University, Nursultan 010000, Kazakhstan; [email protected] (M.M.); [email protected] (A.P.) * Correspondence: [email protected]; Tel.: +7-(7172)-70-65-96 Received: 5 September 2020; Accepted: 13 October 2020; Published: 19 October 2020 Abstract: Advanced methods for manufacturing high quality parts should be used to ensure the production of competitive products for the world market. Investment casting (IC) is a process where a wax pattern is used as a sacrificial pattern to manufacture high precision casting of solid metal parts. Rapid casting is in turn, a technique that eases the IC process by combining additive manufacturing (AM) technologies with IC. The use of AM technologies to create patterns for new industrial products is a unique opportunity to develop cost-effective methods for producing investment casting parts in a timely manner. Particularly, stereolithography (SLA) based AM is of interest due to its high dimensional accuracy and the smooth surface quality of the printed parts. From the first appearance of commercially available SLA printers in the market, it took a few decades until desktop SLA printers became available to consumers at a reasonable price. Therefore, the aim of this review paper is to analyze the state-of-the-art and applicability of SLA based 3D printing technology in IC manufacturing, as SLA based AM technologies have been gaining enormous popularity in recent times. Other AM techniques in IC are also reviewed for comparison. Moreover, the SLA process parameters, material properties, and current issues are discussed. Keywords: Stereolithography (SLA), investment casting; rapid casting; pattern; photopolymers 1. Introduction For thousands of years metal casting has been recognized as one of the main techniques for producing metal goods. Even today, it remains widely used by the industry. Holtzer et al. [1] indicated the constantly growing share of the foundry industry as a means of production for metal products. Despite continuous development of other production technologies, the foundry industry remains a significant and constant element of world economies. In regard to materials nomenclature, gray iron has a significant fraction of production volume. For example, in 2010 the global production in the foundry industry showed a 44 million ton production of grey iron, whereas the production of nonferrous metals showed 15 million tones, and steel 10 million tones. The market share of produced metals is shown in Figure1. From the diagram it can be seen that the automotive, general engineering, and construction industries are the main market players. According to Holtzer’s study, the highest priorities for further development are modeling, prototyping, and production. Therefore, the advances in such areas such as rapid prototyping (RP) and rapid casting (RC) are of particular importance to ensure competitiveness of the foundry industries. Micromachines 2020, 11, 946; doi:10.3390/mi11100946 www.mdpi.com/journal/micromachines Micromachines 2020, 11, 946 2 of 27 Micromachines 2020, 11, x 2 of 27 Construction and Others Infrastructure (Electronics, Systems Medicine, 10% Aviation) 10% Automotive industry (motorization) Engineering 50% industry 30% Figure 1. Main markets served by th thee foundry industry [[1].1]. 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