Parameter effects and process modeling of FFF-TPU mechanical response

Fused Filament Fabrication (FFF) process employs thermoplastic materials in filaments form to build functional components by selectively placing extruded material progressively in thin sheets. Thermoplastic Polyurethane (TPU) is a high potential material for elastic and wearable electronics or medical applications due to its lower stiffness than PLA and ABS materials. This research investigates the effects of two independent 3D printing parameters, Layer Height (LH) and Nozzle Temperature (NT), on the Mechanical Response (MR) of FFF 3D printed TPU parts. Tensile, flexural and impact tests were conducted. The values studied herein are the Ultimate Tensile Strength (T-sigma(b)), the Tensile Modulus of Elasticity (T-E), the Flexural Stress at Break (F-sigma(b)), the Flexural Modulus of Elasticity (F-E) and the Impact Strength (IS). Pure TPU pellets were used to produce the filament. Then, specimens were 3D printed with three different LT and NT levels and nine experiments were conducted, according to the full combinatorial design. Experiments were repeated three times each (3x9 = 27). The results were analyzed and modeled using descriptive tools, main effect plots, ANOVA, and interactions charts. It was found that the LH and NT are affecting all the MR values. The 0.2 mm LH and 215(o)C NT optimized the MR values.