Achieving effective interlayer bonding of PLA parts during the material extrusion process with enhanced mechanical properties

Abstract

The additive manufacturing technique of material extrusion has challenge of excessive process defects and not achieving the desired mechanical properties. The industry is trying to develop certification to better control variations in mechanical attributes. The current study is a progress towards understanding the evolution of processing defects and the correlation of mechanical behavior with the process parameters. Modeling of the 3D printing process parameters such as layer thickness, printing speed, and printing temperature is carried out through L27 orthogonal array using Taguchi approach. In addition, CRITIC embedded WASPAS is adopted to optimize the parts' mechanical attributes and overcome the defects. Flexural and tensile poly-lactic acid specimens are printed according to ASTM standards D790 and D638, respectively, and thoroughly analyzed based on the surface morphological analysis to characterize defects. The parametric significance analysis is carried out to explore process science where the layer thickness, print speed, and temperature significantly control the quality and strength of the parts. Mathematical optimization results based on composite desirability show that layer thickness of 0.1 mm, printing speed of 60 mm/s, and printing temperature of 200 °C produce significantly desirable results. The validation experiments yielded the maximum flexural strength of 78.52 MPa, the maximum ultimate tensile strength of 45.52 MPa, and maximum impact strength of 6.21 kJ/m2. It is established that multiple fused layers restricted the propagation of cracks with minimum thickness due to enhanced diffusion between the layers.

Correlation between the part quality, strength and surface roughness of material extrusion process

“…Higher the bonding between the layers of the MEX part, closer it will be to the homogenous injection moulded parts of the same material (Ali and Alazawi, 2022; Sood et al , 2010); the bonding between the layers totally depends on the process parameters i.e. build speed, layer height and the nozzle temperature (Kumar et al , 2023). The build speed, layer height and the nozzle temperature are inter-related parameters.…”

“…The sample under three-point bending load faces compressive and tensile stresses. The bending strength of layered structures depends on the interlayer adhesion (Kumar et al , 2023; Syrlybayev et al , 2021). Stronger the interlayer adhesion, larger will be the stress before failure.…”

Multiscale characterization of additively manufactured PMMA: the influence of sterilization

“…ASTM D638 samples were extracted from larger 3D printed panels to avoid the edge effect by waterjet cuts, reporting a substantial increase in the Young's modulus and strain to failure. Kumar et al (2023) studied the correlation between the printing parameters and the evolution of defects, where they reported an optimization approach to the processing conditions that resulted in improved flexural, ultimate and impact strengths. Kumar et al (2023) concluded that increasing the number of lain PLA layers by decreasing the layer height constrained the propagation of cracks along the building direction.…”

“…Kumar et al (2023) studied the correlation between the printing parameters and the evolution of defects, where they reported an optimization approach to the processing conditions that resulted in improved flexural, ultimate and impact strengths. Kumar et al (2023) concluded that increasing the number of lain PLA layers by decreasing the layer height constrained the propagation of cracks along the building direction. Chohan et al (2020) used machine learning approaches to achieve maximum tensile, flexural and impact properties of ABS by exploring the effects of layer height, building orientation, raster angle, line deposition width and air gap.…”

Ironing process optimization for enhanced properties in material extrusion technology using Box–Behnken Design

“…Extensive research has been done to investigate and optimize these pre-processing parameters to improve the mechanical properties of MEX parts 32 – 36 . Kumar et al 37 made significant improvements in addressing challenges in MEX. Through a meticulous study involving Taguchi optimization and CRITIC-embedded WASPAS, they optimized layer thickness, print speed, and temperature, resulting in substantially improved mechanical attributes.…”