Effect of filament quality, structure, and processing parameters on the properties of fused filament fabricated short fiber-reinforced thermoplastics

Abstract This chapter is dedicated to the mechanical and tribological properties of neat and particulate or short fiber reinforced thermoplastic specimens and components produced by the fused filament fabrication (FFF) method. Injection molded (IM) samples of the same materials served as a reference. With regard to the tensile or bending loaded strength and stiffness values, the additive manufactured (AM) parts, especially those made of short fiber reinforced polymers, were up to 30 to 50 % weaker than the injection molded ones. The latter could be considered as defect free, whereas the additive manufactured samples had a lot of pores and other weak sites, including a less perfect bonding between neighboring printed filaments. The tribological properties tested under compressive / shear friction and wear conditions against smooth metallic counterparts did not show these big differences between AM- and IM- samples and components. Instead, the types and composition of the materials tested dominated the behavior. Short carbon fiber (CF) reinforced thermoplastics were superior to unreinforced versions, and polyamide (PA) possessed a lower specific wear rate than polyethylene terephthalate glycol (PETG). In short, PA12+CF was better than PA6+CF or PETG+CF. The best load bearing capacity was found for the tribologically optimized thermoplastic composite iglidur® J260, consisting of a thermoplastic matrix with not further specified kinds of particulate fillers, commercially advertised by the company igus® GmbH.