CASTING CONTEST
Bridging Investment Casting Technology to the Future ENTRY: CASTING 110 The inspiration comes from the Iklwa spear, also known
as the assegai, which is a traditional African weapon that originated in the early 19th century during the reign of the Zulu King Shaka Zulu. The Iklwa spear is shorter and heavier than the traditional spear used by Zulu rivals. It was designed for close combat and was intended to be used as a stabbing weapon rather than a throwing weapon. A crucial design consideration was the overall taper of the spearpoint itself. This element affects the amount of post processing, overall performance in penetration, and solidification. The thickest cross sections are near the attachment location and the thinnest by the tip, which in return transitions the edge angle from 30 degrees down to 22 degrees at the tip. The wax pattern was created using SOLIDWORKS to model a scaled version of the spear point by + 3%, which considers the shrinkage of steel, as well as the shrinkage of wax during solidification. This scaled model was then machined to build a tool for injection. The tool was modified to fit the injection core and hardware to complete the mold geometry. The spearhead is at a length of 12.8 inches and a weight of
ENTRY: CASTING 111
This R&D medical implant was used in determining the material properties of gyroid mesh being used for future medical implants. The final part would include the gyroid mesh being tested.
Due to the geometry of the gyroid mesh, conventional
dipping was not an option. However, the geometry did lend itself perfectly to 3D printed ceramic molds utilizing PICS. Printing went seamlessly, accommodating for supports
on the outside of the shell. These supports do not affect the geometry of the final casting. Glass bead blast was used to remove the shell, since chemical means could not be employed.
Once the castings were clean, it was possible to see light through the entire part. The purpose of the gyroid mesh is to be able to have bone material grow around the zinc casting. The zinc would be absorbed by the body, leaving natural bone structure. The gyroid mesh was able to be cast without any plus
metal or any shell defects. This increase in reliability provided more consistent performance results, requiring fewer samples to be produced, which equates to lower costs.
18 ❘ August 2023 ® Name:
Dimensions: 3.950 in. x 0.595 in. x 0.595 in. Weight: Alloy:
Zinc Bone Mesh Bar 0.25 Lbs.
Zamak 5 Zinc CATEGORY: FINE ART
Name:
Dimensions: 12.8 in. Weight: Alloy:
4140
2.22 pounds as-cast, which was reduced during the grinding post processes. The spearhead sports integrally cast logos that were made in separate dies and attached during wax assembly.
CATEGORY: MEDICAL
Spearhead 2.22 Lbs.
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