Characterizing the Accuracy of FDM Rapid Prototyping Machines for Machine Design Applications

This paper presents experiment-based formulas that predict the geometric accuracy of Fused Deposition Modeling (FDM) rapid prototyping (RP) machines in a form suitable for fit and function applications. The proposed method establishes the accuracy of several base-level geometry characteristics such as line straightness and circularity through direct measurements. Statistical analyses are used to establish reliable prediction formulas for the base-level geometry characteristics. The base-level accuracy measures are then used to develop models for higher-level geometric accuracies such as orientation, position, or profile accuracy. The objective of the methods proposed in this paper is to help FDM manufacturers develop reliable measures of accuracy for their machines in a form that is directly applicable to mechanical design applications. The proposed procedure is simple enough that companies that own and use FDM machines can quickly develop in-house accuracy measures that are specifically relevant to their machines. This study does not make any claims regarding the absolute accuracy of FDM machines in general. Rather, the study suggests a methodology for characterizing the accuracy of existing machines or production models in a manner useful to fit and function design work. The methodology applies to other rapid prototyping technologies as well.