October 8, 2018 by admin 0 Comments

Post-processing of FDM parts to improve surface and thermal properties

Authors
Trieu Khoa Nguyen, Bong-Kee Lee
Abstract
Purpose The purpose of this paper is to develop a novel post-processing technique of fused deposition modeling (FDM) parts to improve surface roughness and reduce heat absorption and for high-temperature application in thermoforming process. Design/methodology/approachThe current technique consists of chemical treatment, drying and aluminum coating. First, surface morphology was investigated using FDM specimens with a flat surface. The heat absorption characteristic was also analyzed by Taguchi-based design of experiment and modified lump-capacity model. In addition, dimensional accuracy and uniformity were investigated under high-temperature conditions, which were similar to a typical thermoforming process, with specimens having concave and convex grooves. Findings It was verified that the proposed post-processing technique could efficiently improve surface quality of FDM parts with the arithmetic average surface roughness of 2.06 µm. In addition, the coated aluminum layer was found to reflect the heat radiation, resulting into a sufficient reduction of heat absorption. From the investigation of dimensional accuracy and uniformity, it was found that the current technique produced maximum change of 0.11 mm and uniform thickness of an aluminum layer within 0.07 mm. Originality/value The present study establishes a novel post-processing technique, enabling to treat the surface of FDM parts for high-temperature applications. It provides a simple way of using typical FDM parts for a thermoforming process as the mold cores. Furthermore, it can be used in other rapid tooling technologies, consequently widening the application areas of FDM.

July 31, 2016 by admin 0 Comments

Adaptive modeling method for 3-D printing with various polymer materials

Authors
Gobong Choi & Sungmin Kim
Abstract
An adaptive modeling method has been developed to improve the accuracy of an FDM type 3-D printer especially when printing complex small objects. The thermal and flow properties of PLA, ABS, and HIPS were measured using various types of rheological analysis. The relationship between those results and dimensional errors were analyzed. From this relationship, calibration factors were calculated for correcting the error between virtual and actual models. Image processing software has been developed to measure the dimension of printed samples. A model generation software has been developed to generate calibrated models using adaptive modeling method. The efficiency of system was verified through statistical analysis on the difference between the models with and without calibration.