Direct Digital Manufacturing of ABS parts: an Experimental Study on Effectiveness of Proprietary Software for Shrinkage Compensation

The diffusion of Digital Additive Manufacturing technologies is leading to new needs by industrial research and development sectors. For instance mating additive manufactured parts is not a simple task, due to low accuracy typical of several additive technologies, such as Fused Deposition Modeling. Several papers report studies on how Fused Deposition Modeling accuracy is affected by process parameters. One of the most important aspects is the role of shrinkage during the transition from a semi-liquid state to solid and cooling at solid state. To avoid this drawback a Shrinkage Compensation Factor (SCF), an operator-controlled variable that affects the overall accuracy of the product, is embedded in the control software of FDM machines. In this paper the authors report a study on the influence of working parameters on FDM dimensional accuracy, focusing their attention on the validity of the Shrinkage Compensation Factor, especially when applied to cave parts and proposing a method to improve the accuracy of parts.