Media Contact

Ashley Lindstrom
Communications Coordinator

The mechanical engineering building got a new addition recently. A rolling ball structure was recently placed in the front entry hall to the building. The model was designed by Kelly Alexander, a recent graduate from the department. It was made during her senior year as an independent project at the request of department chair Dr. Joe Beaman.

Selective laser sintering

The model was originally made in order to demonstrate selective laser sintering (SLS). SLS is a rapid manufacturing technique which was developed at the University of Texas by Dr. Carl Deckard in the mid-80s. The technique uses a high power laser to fuse particles of plastic, metal, ceramic, or glass powder into a three-dimensional object. First, a roller lays out a fine layer of powder in the build chamber. A laser fuses together the powder into the bottom layer of the object. Next, a second layer of powder is rolled out, and the laser fuses the next layer of the object. This process continues until the build chamber is filled with powder. The object is found within the powder. The object is essentially a finished product, with no need for assembly, as the machine has built each piece in place. The powder is then cleaned off and the product is ready.

Rapid prototyping or manufacturing processes like selective laser sintering are significant because they allow a manufacturer to build a part directly from a 3D model without any specialized tooling. Parts can be manufactured relatively quickly and in any quantity, allowing designers to make design changes without substantial investments or waste.

The Structure

Woodcut dating from 1511.

Woodcut dating from 1511.

A portion of the structure was an Archimedes screw. The Archimedes screw has been around since at least the 3rd century B.C.E. It is believed to have been invented by Greek mathematician Archimedes. The device consists of a screw inside a hollow pipe, and is traditionally used to transfer water from a low-lying area into an irrigation ditch. Miss Alexander's model transfers marbles from the bottom of the screw to the top, which then roll down a double helix slide to the bottom to repeat the procedure. The screw is manually turned via a handle at the bottom of the device. A traditional Archimedes screw would be manually turned, or turned by a windmill.

Today, Archimedes screws are used for more than simple irrigation. They are often used in land reclamation. They are also commonly used in fish hatcheries to safely transport fish. Such devices are referred to as pescalators. Archimedes screws are also used in sewage treatment plants.

UT ME Alumna Kelly Alexander

UT ME Alumna Kelly Alexander

The Project

The structure was created at the request of Dr. Beaman. The requirement for the assignment was that it should demonstrate the unique manufacturing applications of the SLS process. These include interlocking components manufactured already in assembly, abstract shapes that would be difficult to machine, small internal details that could not be machined in a single part, and a high level of customizability for each piece. She wanted the project to mave a mechanical component with moving pieces, and was drawn to the idea of a rolling ball structure.


She designed the part using Pro/ENGINEER (Pro/E), a 3D CAD program. As this was her first time using Pro/E, designing the piece also involved learning the software. About the design process, she said, "That was probably the hardest part of the project. I knew what I wanted in my head, but getting it drawn up was more difficult." The project took her several months and several revisions to complete, but in the end, the model worked as intended.

Kelly Alexander

Miss Alexander was originally pursuing an education in mechanical engineering to further her desire to work in toy design. She later chose a different path, and since graduating last year, works for Samsung Austin Semiconductor. Samsung Austin Semiconductor is a manufacturing plant which produces semiconductor wafers for Samsung. Miss Alexander works on the exhaust systems for the site. Her work involves improving the system and resolving problems.

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