Optimizing process parameters of a material extrusion–based overprinting technique for the fabrication of tensile specimens

Injection molding (IM) and additive manufacturing (AM) have been widely used in the manufacturing industry because IM excels at mass production and AM allows for a great deal of design freedom. In this context, a novel hybrid manufacturing (HM) combining both has been investigated. The tensile performances of acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) specimens were studied and compared via the Taguchi method using an overprinting technique. In contrast to the extensively studied overmolding technique, we utilized AM through material extrusion to directly fabricate onto injection-molded substrates. Three parameters in this manufacturing process were studied: infill density, printing speed, and extrusion temperature. Taguchi’s L9 array, which has nine runs with three repeated specimens for each, was used to create a total of twenty-seven specimens with different processing settings in one material. All finished specimens’ dimensions were subjected to the ASTM D638-III standard. The results showed that a combination of higher infill density (75%), midprinting speed (70 mm/s), and high extrusion temperature (210 °C) was required for greater tensile strength in PLA specimens. The parameters of 75% infill density, 100 mm/s printing speed, and 220 °C extrusion temperature were required for the ABS specimens to have an exceptional tensile strength. This research provides a fundamental understanding of this promising manufacturing technology, which has the potential to produce functional items with exceptional properties such as flexural behavior, impact behavior, and certain custom-tailored features.