Optimizing Process Parameters of Direct Ink Writing for Dimensional Accuracy of Printed Layers

Abstract

Direct ink writing (DIW) belongs to extrusion-based 3D printing techniques. The success of DIW process depends on well-printable ink and optimized process parameters. After ink preparation, DIW process parameters considerably affect the parts' dimensional accuracy and process parameters optimization for dimensional accuracy of printed layers is necessary for quality control of parts in DIW. In this study, DIW process parameters were identified and divided into two categories as the parameters for printing a line and the parameter from lines to a layer. Then a two-step method was proposed for optimizing process parameters.Step 1 was to optimize process parameters for printing a line. In Step 1, continuity and uniformity of extruded filaments and printed rectangular objects were observed in screening experiments to determine printability windows for each process parameter. Then, interaction effect tests were conducted and degree of freedom (DOF) for experiments was calculated followed by orthogonal array (OA) selection for Taguchi design. Next, main experiments of line printing based on Taguchi method were conducted. Signal-to-noise ratio (SNR) calculations and analysis of variance (ANOVA) were performed to find the optimal combination and evaluate the significance respectively. Step 2 was to optimize the parameter from lines to a layer. InStep 2, the average width of the printed line under optimal condition was measured firstly. Then, single-factor tests of rectangular object printing were conducted to find the optimal parameter from lines to a layer. After these two steps, confirmation results were conducted to verify the reliability of the proposed method and the method robustness on other shapes and other materials; parameter adaptability in 3D parts printing from printed layers' analyses for the proposed method and parameter adaptability in constructs fabricated as 100% infill or with porosities.

Modeling and evaluation of freeform extruded filament based on numerical simulation method for direct ink writing

“…CA (reference: C0759) was added to the combination of all batches prepared as a crosslinking agent on the same day by means of a spatula. Nivea Crème with well printability is often used as printability reference for inks to test the process parameters in DIW [17] as many inks in DIW are designed and produced to have the same printability of Nivea Crème [30]. In this study, Nivea Crème (Art.…”

Numerical simulation and experimental validation of deposited corners of any angle in direct ink writing

“…Parameters in numerical simulations include parameters of material properties, critical parameters of geometrical model and process parameters. Parameters of material properties of the selected ink were obtained experimentally in our previous work [37] and are listed in Table 2. For critical parameters of geometrical model, the values of n d , n D and p D are set as 0.84 mm, 1.22 mm, and 21.6 mm, which match the actual dimensions of the used DIW 3D printer in the experimental verification, respectively.…”

Predicting dimensional accuracy in 3D printed polydimethylsiloxane‐carbon nanotubes composites via machine learning

“…7 The utilization of printable ink and appropriate processing parameters in the DIW process is imperative for achieving satisfactory printed components. 8 Printability examination requires rheological studies, where ink should possess shear-thinning behavior and high storage modulus. Thus, ink rheology significantly affects the extrusion process, shrinkage, shape retention, and shape conformity.…”

“…10 The uniformity and continuity of the extruded strands in DIW were optimized through screening experimentations to determine the print fidelity windows for each processing parameter. 8 Several studies have been conducted recently on selecting processing parameters for DIW. Nevertheless, none of these studies were able to determine the optimal values of these parameters, and very few studies examined the significance of processing parameters, optimization, and prediction for DIW by providing a printability predictive band.…”

“…Thus, ink rheology significantly affects the extrusion process, shrinkage, shape retention, and shape conformity 7 . However, the part's dimensional accuracy is impacted substantially by the DIW processing parameters related to the equipment setup 8 . The general DIW parameters include extrusion multipliers, printing speed, extrusion pulses generated to extrude materials, stand‐off distance between the nozzle and bed, and retraction control.…”