Bond and part strength in fused deposition modeling

Abstract

Purpose The purpose of this paper is to investigate the factors governing bond strength in fused deposition modeling (FDM) compared to strength in the fiber direction. Design/methodology/approach Acrylonitrile butadiene styrene (ABS) boxes with the thickness of a single fiber were made at different platform and nozzle temperatures, print speeds, fiber widths and layer heights to produce multiple specimens for measuring the strength. Findings Specimens produced with the fibers oriented in the tensile direction had 95 per cent of the strength of the constitutive filament. Bond strengths ranged from 40 to 85 per cent of the filament strength dependent on the FDM processing conditions. Diffusion, wetting and intimate contact all separately affect bond strength. Practical implications This study provides processing recommendations for producing the strongest FDM parts. The needs for higher nozzle temperatures and more robust feed motors are described; these recommendations can be useful for companies producing FDM products as well as companies designing FDM printers. Originality/value This is the first study that discusses wetting and intimate contact separately in FDM, and the results suggest that a fundamental, non-empirical model for predicting FDM bond strength can be developed based on healing models. Additionally, the role of equilibration time at the start of extrusion as well as a motor torque limitation while trying to print at high speeds are described.

Weld formation during material extrusion additive manufacturing

“…This is a clear manifestation of the conclusion mentioned above, that the tear energy is rather sensitive to temperature, but less so to print speed, similar to the tensile results from Coogan and Kazmer. 57 As weld time increases the tear energy increases, however, the bulk value is not reached; it does not exceed 70 % of the bulk value. This underperformance is also seen in comparisons of injection molded and ME manufactured ABS tensile, flexural samples where ME samples are 30 % to 70 % the strength of injection counterparts 58 , and in ULTEM 4 tensile samples where the z-axis tensile strength is 50 % of the injection molded counterpart.…”

Mechanical strength of welding zones produced by polymer extrusion additive manufacturing

“…[1–4] Most AM processes, such as laser sintering, photopolymerization/stereolithography, or material extrusion-based techniques, involve the creation of welds, which are inherent weak points in the parts. [5–7] As AM techniques continue to increase in popularity, facile methods that enable the quantification of the mechanical strength of these bonds or welds must be developed. [6]…”

Harnessing irreversible thermal strain for shape memory in polymer additive manufacturing

“…Poor mechanical performance, relative to non‐AM parts, and anisotropic properties are widely reported in the literature . Additionally, mechanical property dependence on build orientation, air gap, raster angle, extruder temperature, and layer thickness have also been reported …”