Application of Stereolithography Based 3D Printing Technology in Investment Casting

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; pattern; photopolymers; rapid casting.

Figure 1

Main markets served by the foundry industry [1].

Figure 2

Schematic illustration of the investment casting (IC) process: (a) Metal mold prepared for wax injection; (b) Wax pattern making by injection; (c) Wax ejected from the mold; (d) Wax patterns assembled in a tree; (e) Coating with ceramic slurry; (f) Stucco coating; (g) Dewaxing through heating; (h) Metal pouring; (i) Destroying ceramic shell; (j) Casted part ready to be cut off from the assembly.

Figure 3

Most common applications for additive manufacturing (AM) [11].

Figure 4

Cad model (a) and the pattern invested with ceramic shell (b) [13].

Figure 5

Schematics of SLA.

Figure 6

Schematics of different machine configurations.

Figure 7

A cured line of a polymer during the SLA process.

Figure 8

A section of a part generated by laser scanning [57].

Figure 9

QuickCast 2 hexagonal build structure [70].

Figure 10

(a) The blade prototype; (b) the investment cast of the hollow turbine blade (front view); (c) the investment-cast of the hollow turbine blade (side view) [77].

Figure 11

Example of objects made from ceramic resins; printed on CeraFab 7500 [57].