Using Resin-Bonded Hollow Aluminosilicate Microspheres to Create Patternless Molds for Rapid Casting

Date of Award

12-2024

Degree Name

Doctor of Philosophy

Department

Engineering and Applied Sciences

First Advisor

Sam Ramrattan, Ph.D.

Second Advisor

Pavel Ikonomov, Ph.D.

Third Advisor

Lee Wells, Ph.D.

Keywords

3d-printing, hollow aluminosilicate microspheres, hybrid additive/subtractive manufacturing, metal casting, rapid casting

Abstract

Rapid Casting is a term describing techniques and technologies that allow cast metal parts to be made faster, cleaner, and more flexibly by replacing traditional resource-intensive processes with automated aspects. The industry’s desired end goal is to use these rapid techniques to create metal casting lines capable of high part mixes that pass seamlessly from mold, melt, fill, and shake-out without the touch of human hands. Analogous to an assembly line, each link of the process chain directly integrates into the next accomplishing flexible, diverse, and lean production.

Presently there are several forms of rapid casting commonly used in patternless mold-making operations that utilize additive manufacturing approaches. However, these additive processes require support materials to create negative drafts, cantilevers, and undercuts. Removal of these supports represents an additional required post-processing step that is highly bespoke to a mold’s design. This additional step, unique to each mold design, prevents direct integration into the desired automated foundry line.

An approach that may solve this problem is a hybridized rapid-casting process that first subtractively removes material from pre-cured layers. The pre-cured mold material, being lightweight and strong enough to be self-supporting, would then be additively deposited or assembled in layers until a mold is rendered. This technique requires a refractory mold material, machinable via conventional tooling, which is dimensionally stable and rigid enough to be self-supporting. One such candidate material is resin-bonded Hollow Aluminosilicate Microspheres (HAM).

Resin-bonded HAM is a refractory material that can not only be machined, but can be used in a hybrid additive/subtractive rapid casting approach to create direct patternless cast metal molds without the use of support materials. This research aims to demonstrate that this material can be used in this hybrid approach and render castings comparable to patternless molds made via current additive rapid casting approaches. Using 3D-printed silica sand for comparison, the following research outlines an initial investigation into the use of HAM with the intent of a) determining the CNC milling ability and properties of the material and how its surface roughness compares, b) examining and comparing its performance properties as a casting mold system using standardized and non-standardized lab testing, c) examining the dimensional and physical as-cast effects HAM may have on cast components, and d) demonstrating the hybrid technique using the HAM material by conducting multiple proofs of concept.

Access Setting

Dissertation-Abstract Only

Restricted to Campus until

12-1-2026

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