PA12 Multi Jet Fusion 3D printed samples: dependence of chemical, thermal and mechanical properties by printing direction, position inside the JOB and accelerated aging

This study is devoted to enlarge the knowledge on the conformity and applicability of the components produced through the Additive Manufacturing technology created by the company HP Inc., the Multi Jet Fusion (MJF). This research was defined and developed with the collaboration of three entities: Valeo Santena, Polytechnic of Turin and Valeo Martos. Valeo, a multinational in the automotive field, has been using these types of processes for rapid prototyping, for about 30 years. In recent years, Valeo Santena has been looking to take this technology to the next level: series production. ??The purpose is to analyze the evolution of the chemical, thermal and mechanical properties of Polyamide 12 (PA12) components 3D printed with MJF 4200, in relation to their position in the printing area, orientation and aging. Assuming the specimen’s characteristics as symmetrical in the printing area, three points considered cruxes are analyzed. The samples, with their dimensions dictated by the specific standards, are printed in these points, and with different printing orientations. Regarding accelerated aging, the “Environmental specification for electrical/electronic (E/E) components” is followed, relating to Valeo Santena product line, the “Interior Switches and Control” (ISC). This means that the specimens, tested in a climatic chamber where Temperature and Humidity are controlled, are inspected at ⅓ and at the end of the vehicle’s life. The typical service life target refers to the 95th percentile of customer usage over the period of 10 years, which means 150.000 miles, or 15 years, depending on the device application. ??The material is characterized by means of infrared spectrophotometry in attenuated total reflectance (FTIR-ATR), to examine the functional groups. The thermal analysis used is differential scanning calorimetry (DSC). As for the mechanical tests, the evolution of Young's modulus (E) is observed through the tensile test and the flexural modulus through three-point bending flexural test. To determine the notch toughness of the material, the Izod impact strength test is also carried out, designing the indenter and the base with the annexed vise. Lastly, the hardness with a Shore durometer type D and the microindentation hardness testing with the Vickers indenter.