Dissertations and Theses @ UNI

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Open Access Thesis

Keywords

Three-dimensional printing--Equipment and supplies; Sand, Glass--Industrial applications;

Abstract

The purpose of this study was to assess the performance characteristics of commercially available round grain silica sand for the use in three-dimensional sand printers. Two different average diameters were selected to examine the effects of screen distribution on printing performance; these diameters were 57-grain fineness number (GFN) and 70 GFN. These sands were a high purity round grain silica and had low trace contaminates, to reduce any possible influence from contaminates.

The resin system utilized in this investigation was a commercially available Furan resin system. Two test specimens were used in this study the American Foundry Society (AFS) tensile “dog bone” and 1” x 1.5” x 2” rectangle samples to calculate the printed part sand density. The resin content during the printing trials was adjusted by holding the resin droplet constant and changing the sand volume and the droplet to droplet distance. The cubic volume of sand is equivalent to the voxel size. The voxel size is determined by the resolution machine settings for the sand printer used in this investigation. Eight trials were printed with the four voxel sizes and repeated for the two sand GFNs. This was followed by a complete replication of the machine settings and sand types for a grand total of sixteen data sets.

Each trial consisted a total of thirty dog bones with ten placed parallel to the three Cartesian axes’ (X, Y, and Z). There were four density samples per axial direction for a total twelve samples per trial. The dog bone samples were evaluated on the mass, tensile strength, scratch hardness, permeability, and loss of ignition (LOI) to determine resin content of the bonded sample.

The measured resin content on the bonded samples by LOI testing showed to be 0.97% to 2.02% based upon the sand voxel size. Analysis of Variance (ANOVA) was used to determine that there was no axial difference between the resin content of printed samples. The tensile strength results demonstrated that the GFN did impact the strength performance characteristics of the tested sands. The 57 GFN sand experienced a linear reduction of strength as the sand voxel size increased. The 70 GFN exhibited a unique profile for the middle voxel shapes as the tensile strength remained the same for two different resin levels of 1.5% and 1.3%. Both sand distributions experienced a reduction of Z-axial strength below 1% resin. The 70 GFN experienced a greater reduction of the Z-axial strength than the 57 GFN. This difference was attributed to the greater amount of grain to grain contact points within the 70 GFN sand.

The investigation confirmed that at the traditional Furan operating resin levels of 1.25% to 1.5% there was indeed a difference in physical properties between the two screen distributions for 3D printed sand (3DPS). Previously published studies for 3DPS utilized the manufacturer consumables and reported the physical properties. This investigation confirmed that a non-qualified sand will perform in 3DPS applications with the proper machine settings are utilized.

Year of Submission

2018

Degree Name

Master of Science

Department

Department of Technology

First Advisor

Scott Giese, Chair, Thesis Committee

Date Original

5-2018

Object Description

1 PDF file (xii, 89 pages)

Language

en

File Format

application/pdf

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