ADDITIVE MANUFACTURING PROCESS PARAMETER INFLUENCE ON MECHANICAL STRENGTH OF ADHESIVE JOINTS, PRELIMINARY ACTIVITIES

The work illustrates how building parameters of the Additive Manufacturing (AM) process fused filament fabrication can affect not only the mechanical properties [1] but also the surface wettability and morphology. Wettability and morphology are relevant factors in bonded joints performance [2]. Advantages of polymeric AM are to allow a re-design of components with locally controlled properties [3] and integrated functions. Major limitations are related to the lack of material testing standardization and constraints due to the build volume and to the object orientation for printability: the latter problem can be addressed with the use of bonded joints that allow to create bigger assemblies from smaller parts optimally designed to take advantage of the anisotropy of the material and without the structural drawbacks due to other joining method, such as stress concentration in bolted joints. As for the Mechanical properties, they are obtained with uniaxial tensile tests using MaCh3D [4], an innovative cost effective solution for materials testing. The as built surface properties are investigated quantitatively and qualitatively using a plate specimen of 15 × 15 × 1.2 mm. Roughness parameters are measured by surface scanning with a CCI Taylor-Hobson 3D optical profilometer while contact angle values between specimens and a drop of Milli-Q water are measured in order to evaluate wettability. Different materials, such as ABS and PLA, are characterized at different combinations of nozzle temperature, print speed and layer thickness. The analysis of the collected data provide information on how building parameters can modify two fundamental aspects in adhesive joints such as surface roughness and wettability in order to maximize joint performance.