Analysis of Bonding Methods for FDM-Manufactured Parts

The fused deposition modeling (FDM) additive manufacturing (AM) technology has been valuable for producing a variety of concept models, functional prototypes, end-use parts and manufacturing tools using a range of durable thermoplastic materials. The largest individual component that can be produced in FDM depends on the dimensions of the build chamber for the specific FDM system being used, with a maximum build chamber size available of 914 x 610 x 914 mm. This limitation is not unique to FDM as all AM systems are constrained by a build chamber. However, by using thermoplastic materials, individual components can be bonded together using different methods to form a single piece. Bonding can be used to help reduce building time and support material use, and also allows for the fabrication and assembly of final products larger than the build chamber. This work investigated different methods for bonding FDM-manufactured parts, including the use of five different adhesives and solvents as well as two different welding techniques (hot air welding and ultrasonic welding). The available FDM materials investigated included acrylonitrile butadiene styrene (ABSi, ABS-M30, ABS-M30i), polycarbonate (PC, PC-ABS, PC-ISO), polyphenylsulfone (PPSF), and ULTEM 9085. Bonding strengths were characterized by comparing ultimate tensile strengths at break and analyzing the mode of failure. Overall, the bonding method of hot air welding produced the strongest bond for all the materials investigated except for ULTEM 9085 for which the strongest bond was achieved with the two-part epoxy adhesive Hysol E-20HP.