Purpose Due to intrinsic limitations, fused deposition modelling (FDM) products suffer from the bad surface finish and inaccurate dimensional accuracies restricting its usage in many applications. Hence, there is a need for processing polymer patterns before, during and after their productions. This paper aims to highlight the importance of pre- and post-processing treatments on the FDM-based acrylonitrile butadiene styrene patterns improving its surface quality so, that it can be used in rapid investment casting process for making medical implants and other high precision components. Design/methodology/approach As a part of pre-processing treatment, the machine parameters affecting the surface quality were identified and optimised using design of experiments. The patterns developed after the first stage of optimisation were given different post-processing treatments, which included vapour smoothening, chemical treatment and sand paper polishing. The results were compared and the best ones were used for making patterns for making medical implants via rapid investment casting technique. The surface quality was checked while the dimensional changes happening during the stages of this hybrid technique were recorded using a three-dimensional optical scanner. Findings The surface roughness of the FDM based ABS patterns reduced from 21.63 to 14.40 µm with pre-processing treatments. Chemical treatment (post-processing treatment) turned to be the most suitable technique for reducing the surface roughness further down to 0.30 µm. Medical implants that used these pre- and post-processing treatments gave an average surface roughness of 0.68 µm. Cost and lead time comparisons showed that rapid investment casting technique can be a better method for low volume, customised and with specific requirements. Originality/value FDM parts/medical implants produced by rapid investment casting technique suffer from the inferior surface finish and inaccurate dimensional accuracies limiting its applications. A systematic approach to overcome this issue is presented in this research paper. This will directly help the end users and the manufacturers of medical implants, wherein, better surface finish and dimensionally accurate components are expected.

Purpose Three-dimensional (3D) printing, one of the important technological pillars of Industry 4.0, is changing the landscape of future manufacturing. However, the limited build volume of a commercially available 3D printer is one inherent constraint, which holds its acceptability by the manufacturing business leaders. This paper aims to address the issue by presenting a novel classification of the possible ways by which 3D-printed parts can be joined or welded to achieve a bigger-sized component. Design/methodology/approach A two-step literature review is performed. The first section deals with the past and present research studies related to adhesive bonding, mechanical interlocking, fastening and big area additive manufacturing of 3D printed thermoplastics. In the second section, the literature searches were focused on retrieving details related to the welding of 3D printed parts, specifically related to friction stir welding, friction (spin) welding, microwave and ultrasonic welding. Findings The key findings of this review study comprise the present up-to-date research developments, pros, cons, critical challenges and the future research directions related to each of the joining/welding techniques. After reading this study, a better understanding of how and which joining/welding technique to be applied to obtain a bigger volume 3D printed component will be acquired. Practical implications The study provides a realistic approach for the joining of 3D printed parts made by the fused deposition modeling (FDM) technique. Originality/value This is the first literature review related to joining or welding of FDM-3D printed parts helping the 3D printing fraternity and researchers, thus increasing the acceptability of low-cost FDM printers by the manufacturing business leaders.

3D printing technology is making its mark in automotive, aerospace, and bio-medical-related industries. It is considered a viable option for the direct manufacturing of final parts. However, it is not possible to print longer parts in a single attempt due to the bed size limitation of printers. This problem can be addressed by employing a polymer joining technique as a secondary operation. Moreover, low mechanical strength and inferior geometrical qualities like the flatness of the joined parts restrict its real-time industrial application. Here, an attempt is made to join a longer part (typical of an aircraft wing) using friction stir welding technique. Joining was performed on 3D printed similar/dissimilar thermoplastic parts. Tensile test results showed that friction stir welding of 3D printed parts (for both similar/dissimilar) produced relatively weaker joints compared to the base material. Various important process parameters of 3D printing and friction stir welding technique, namely part infill percentage, material combination, tool rotational speed, traverse speed, and tool pin taper angle were optimized by means of ANOVA. Optimization was aimed at maximizing the weld strength, elongation, hardness, and desired flatness. The results suggested that the material combination and tool pin taper angle play a significant role in the weld's strength as well as its geometric properties (flatness). The results were validated by adopting the optimized parameters for successful joining of the wing section of an unmanned aerial vehicle. A span of 320 mm, with a metrological acceptable flatness value of 0.41 µ/m could be successfully achieved on an existing 3D printer whose bed size limit was 240 mm.

No abstract

No abstract