Effect of Infill Percentage and Raster Angle in Fused Deposition Modeling (FDM) Process on Shape Memory Properties of Poly (lactic acid) and Comparison with Compression Molding

In this study, the effect of processing parameters on the shape memory properties of 3D-printed PLA products, in the fused deposition modeling (FDM) method, was investigated. The FDM is one of the most widely used additive manufacturing methods due to its low cost and high process capability in fabricating components with complex geometries. Manufacture of shape-memory materials in a 3D printing process is also called 4D printing. Utilizing the three-point bending test, the shape memory behaviors of the printed specimens, with infill percentages of 50% and 100% and printing angles of 0, ±45, and 90 degrees, were measured. To evaluate and compare the effects of the 3D printing process parameters on the shape memory properties, similar specimens with the same geometry were produced using the compression molding process. According to the results, the force recovery of the samples with 100% and 50% fill percentages were 61.6% and 68.9%, respectively, compared to 60.8% for the counterpart samples produced via compression molding. Also, the shape recovery of the FDM process and the compression molding were recorded as 86.3% and 95%, respectively. Assumingly, the higher density and the lack of porosity of the samples produced via the compression molding process increased the initial programming force and the recovered force, accordingly.