Additive Manufacturing of Polybutylene Terephthalate (PBT) Using the ARBURG Plastic Freeforming (APF) Process

Due to the growing variety of product variants, ever smaller and more complex parts with increasing functionality are required. Specially, individualised electronic sensors and actors are highly interesting for different applications. Additive manufactured parts with integrated, freely arranged electrical components would allow an application specific design. The thermoplastic polymer polybutylene terephthalate (PBT) is characterized not only by its stiffness and heat resistance, but also by its electrical insulation properties and is therefore very suitable as a housing material in electronics. While the processing of granular PBT with the injection moulding process is a standard in industrial production for many years, PBT is currently still one of the thermoplastics that are used only conditionally in the field of additive manufacturing. Mainly AM process tailored materials are available. The additive manufacturing process of ARBURG Plastic Freeforming (APF) offers the possibility of processing application specific PBT plastic granulate in an additive build-up process. This study investigates therefore the printability of flame retarded PBT material with the APF process and provides insights into the properties of printed PBT components. For this purpose, relevant requirements for the additive manufacturing of an integrated electric system are derived from a demonstrator and the corresponding hybrid manufacturing process. The basic printability and the corresponding parameters are shown and properties such as interaction with support materials, water tightness of structures, dimensional accuracy and tensile strength are described. Finally, a printed, individualized sensor housing made of PBT including cavities for conductive tracks is shown.