Ultimate Tensile Strength in Fused Deposition Modeling Considering Process Parameters of Flow Rate and Printing Head Speed

Mechanical properties are important indexes to indicate quality of Fused Deposition Modeling (FDM) parts, and Ultimate Tensile Strength (UTS) is one of the frequently concerned mechanical properties. In the manufacturing process of FDM parts, UTS is affected by many controllable process parameters, such as raster orientation, fill rate, layer thickness, head speed, flow rate and so on. The effects of some parameters have been studied in detail but others have not. In this paper, the effects of flow rate and printing head speed on UTS are examined. An effective Design of Experiments (DOE) method is applied to determine the settings of parameters to obtain the optimal UTS. The two process parameters are set to twenty-four different combinations of six levels of printing head speed and four levels of flow rate in manufacturing process, and FDM specimens from Polylactic Acid (PLA) are manufactured according to the test standard. Five specimens are manufactured under each condition. UTS values of specimens are measured by experimental test of tensile properties. The response surface model and Signal-to-Noise Ratio (SNR) are applied to analyze these UTS data. As a result, flow rate has a significant effect on UTS but printing head speed does not show significant effect in this case, and optimal settings of flow rate and printing head speed are given.