Joining of ABS parts built by material extrusion: Analysis of strength and fracture behavior Bitthal Saraf, Ashu Garg, Suman Saurav, Anirban Bhattacharya* Department of Mechanical Engineering, Indian Institute of Technology Patna, Bihar, India A R T I C L E I N F O Article history: Available online xxx Keywords: Additive manufacturing Material extrusion Raster angle Acetone Strength Fractographs A B S T R A C T The present work proposes an approach of joining the acrylonitrile butadiene styrene (ABS) parts built by material extrusion process using dimethyl ketone (acetone) maintaining different overlap regions to appraise the lap shear force, fracture behavior of bonded joints. The effect of four different raster angles (0  /90  , 15  /75  , 30  /60  , and 45  /-45  ) were also investigated on lap shear strength of acetone bonded joints. Results indicate that the strength of acetone bonded joints was reasonably good and quite comparable when compared with single piece specimen. The highest bond strength was observed for specimen built with 45  /-45  and 0  /90  raster layers for joints with 12.7 and 25.4 mm overlap regions, respectively. Parts fabricated with 45  /-45  raster angle were also pre-treated with acetone vapors for different exposure times before joining with acetone to assess the effect on joint strength. The shear strength of acetone bonded joints significantly drops when the specimen was pre-treated with acetone vapor which further reduces with increase in exposure time. For acetone bonded joints, the stock-break failure with rupture and tearing of raster fibers with several tear ridges marks were also noticed. © 2020 CIRP. Introduction The increased part complexity and manufacturing within the desired time and cost has often drawn the focus of many manufacturing industries towards additive manufacturing (AM) techniques. Deposition by material extrusion one of the exten- sively used AM techniques for building geometrically complex three-dimensional (3D) parts by depositing fused material on build platform through layer-by-layer deposition principle [1]. However, in building by material extrusion process, the mechanical properties, geometric accuracy, surface finish, manufacturing time, and cost of the components majorly depend upon various process parameters– raster width, deposition speed, part orienta- tion, air gap, layer thickness, and raster angle [2–8]. Therefore, it is necessary to effectively acquire optimal process parameters settings to achieve good strength, geometric accuracy, and good surface finish at lower build time. The influences of layer thickness, raster width, and angle, air gap, and part orientation were investigated by Sood et al. [4,5] on dimensional accuracy and mechanical performance of fused deposition modeling (FDM) samples using statistical method. Garg et al. [6] studied different raster angles for surface quality, strength, and fracture behavior of acrylonitrile butadiene styrene (ABS) parts. They reported that the FDM specimens fabricated with 0  raster angle exhibit optimum strength and surface quality. Later, they examined the combined effect of raster angles and build orientation on strength, surface quality, build time and cost [3]. The influence of build orientation, layer height, extruder tempera- ture, and print speed on tensile strength of fused filament fabricated ABS parts were investigated by Abbott et al. [7]. They reported that print speed has large impact on strength, wherein high speed reduces the contact length between layers and yields lower strength. Riddick et al. [8] analyzed different raster orientation and part build direction for tensile failure of ABS parts fabricated on FDM machine. Relationship between mechanical properties and failure were derived through fractographic analy- ses. Galantucci et al. [9] analyzed the effect of chemical post- treatment of FDM samples with dimethyl ketone and water solution on surface quality and reported that surface finish significantly improved after post-treatment. Similar observations were also made by Kuo and Mao [10] when FDM parts were treated with acetone vapors. Garg et al. [11] reported improvement in surface roughness when different parts with flat, curved, and freeform/doubly curved surfaces were treated with cold vapors of acetone. For different applications, it may be quite beneficial to join multiple parts to get large components rather than building single piece component. Thus, the joining of components build by FDM * Corresponding author. E-mail address: abhatta@iitp.ac.in (A. Bhattacharya). https://doi.org/10.1016/j.cirpj.2020.07.008 1755-5817/© 2020 CIRP. CIRP Journal of Manufacturing Science and Technology xxx (2019) xxx–xxx G Model CIRPJ 599 No. of Pages 8 Please cite this article in press as: B. Saraf, et al., Joining of ABS parts built by material extrusion: Analysis of strength and fracture behavior, NULL (2020), https://doi.org/10.1016/j.cirpj.2020.07.008 Contents lists available at ScienceDirect CIRP Journal of Manufacturing Science and Technology journa l home page : www.e lsevier.com/loca te/cirpj