Determinação do impacto do resfriamento forçado na aderência entre camadas na manufatura aditiva

Abstract

With the increasingly widespread use of additive manufacturing, it is essential to have a full understanding of the final mechanical properties of the manufactured parts in order to obtain the full advantages of this technology. From prototypes to functional parts, we are experiencing a shift of the production style, the popularly called “3D Printer” is taking over industries and changing long-lasting concepts. Additive manufacturing offers a big advantage to segments like aviation, where projects last for decades and the weight of a part directly influences the performance of the plane. The possibility to produce organic shapes with ease and to maintain zero stock police, keeping the files and the 3D Printer ready to produce a part on demand, is extremely attractive to this segment. One of the key components present in practically all 3D printers is the material extrusion cooler, which helps to ensure dimensional accuracy as well as improving the finish aspect of the part, but it may end up impacting the mechanical properties of the final part. The study was carried out by making specimens, according to ASTM D636, in PLA and PETG and changing the rate of the cooler for each specimen. With the performance of tensile strength tests, the difference in the yield strength in the area where two layers bond together was determined. With the results, a graphic was elaborated showing the correlation between the cooler speed vs the yield strength. Finally, it was tested whether the behavior is repeated when utilizing materials from another manufacturer. The impact in the yield strength in the bond between layers suffered a reduction greater than 40%, when compared to printed specimens with the cooler turned off. This finding shows that for parts manufactured in order to resist stresses, the best practice is to use the cooler turned off during printing.