The Effects of FDM Print Volume on Surface Finish for Investment Casting Applications

Abstract:

The investment casting (IC) process has been utilized for thousands of years as a versatile and cost-effective way of producing specialized small batch metal castings. This process is commonly chosen over other casting methods due to their near-net-shape characteristics and the overall surface finish quality of their castings. The quality of these castings is the direct result of the quality of the patterns used to make them which have traditionally been made through an injection molding process. Pattern fabrication has been revolutionized by the development of additive manufacturing, which has eliminated the need for an injection molding tool for the wax pattern. This has the benefit of reducing overall cost and expediting the time from design to finished casting. Fused deposition modeling (FDM) is a common choice for these IC patterns due to its simplicity and low cost. Although a common drawback of this process is the poor surface finish inherent with the layering effects of FDM parts. As the industry trends towards small batch larger size castings, it is important to understand the effect these larger-volume FDM patterns have on the final quality of the casting. Since the quality of these castings is directly dependent on the quality of the patterns used to make them, it is crucial to understand how to limit pattern imperfections in the FDM printing process. The areas of study in this experiment seek to examine the relationship between pattern volume and pattern quality. Specific printing parameters and dampening methods are being used in this study in an attempt to prove their viability as a method to improve the final quality of IC castings.