Analysis of shrinkage and dimensional accuracy of additively manufactured tooling for the composite manufacturing

Additive manufacturing has immense potential in reducing time and cost which leads to a significant role, especially in the design iteration phase of various research and development (R&D) projects. Out-of-autoclave tooling for composite manufacturing, which does not need to withstand high temperatures of autoclave, can be manufactured using thermoplastics which have low melting points. However, the tooling needs substantial dimensional accuracy which is compromised due to the prominent shrinkage that the thermoplastic filaments inherently show when it gets cooled down. For this reason, the paper presents the shrinkage compensation that is required to be catered while designing composite tooling to achieve better dimensional accuracies of the composite samples. The most widely used materials which are also selected for this experimental research, are Acrylonitrile butadiene styrene (ABS), Polylactic acid (PLA) and Polyethylene terephthalate glycol (PETG). In this research, CAD model of a standard wind turbine section has been developed. The model is printed with three materials. The printed model is measured and the deviation between the CAD model and the printed model is determined. With the deviation, shrinkage compensation has been determined, which is applied to the CAD model. The process of printing and determination of deviation is repeated. It has been found that through the shrinkage compensation, the deviations are much reduced in the three materials. The validation is performed using the 3D scanning of the shrinkage compensated parts.