A mechanical engineering technology class in manufacturing processes allows IUPUI students to build air-piston engines from scratch. That includes casting the engine parts that go into the working engine.
That’s right – undergraduate students pound out molds, pour 1,500-degree molten aluminum, break out the parts, precisely machine critical features, drill holes and assemble the pieces. The small engines are then attached to an air source, and they are expected to run at 2,000 rpm or more.
“This is a really great learning experience for the students that I’m not sure they get in many other programs,” said Rob Weissbach, chair of the Department of Engineering Technology. “They’re really understanding the construction side as well as the design side and being able to put the pieces together.”
Description of the following video:
[Video: Footage of machines and work being done in an engineering lab.
[Logo and words appear in upper-left corner: IUPUI presents]
[Vincent Shiue appears on camera and speaks: So we’re gonna be making a flywheel for our piston engine. … ]
[Title: Vincent Shiue, Senior, mechanical engineering and technology]
[Shiue … The flywheel is what rotates and keeps the piston rolling…
[Shiue is now in voiceover, with images of people working the machinery: … so it doesn’t stop and stall. So, this is the mold that we’re using. It’s gonna make the frame – or not the frame. The flywheel. And we’re gonna pack some sand in here to create the negative.
[Video: Packing red sand into containers to create the mold for the engine part.]
[Shiue speaks in voiceover as the video shows a student removing a container of molten metal from an oven that looks like a microwave and then pouring it into molds: There we go. So metal is around 1,500 degrees right now, Fahrenheit. Gonna pour it in in one side and then he’s gonna pour it until he sees it come out the other side, like that. All right, he’s gonna pour the extra in here for us to reuse later.
[Video: Scraping access molten metal into scrap bin.]
[Shiue speaks, standing next to the person who was pouring the metal: We will leave this for around 15 minutes or longer to let it cool down, and then we’ll come back and break it out, which we’ll show you right now.]
[Shiue and the other student are breaking out the mold. Shiue speaks: So here’s the finished part. We’ll have to cut off these pieces on the ends. These are to help it cool better and also for the metal to go in and out.]
[Video: Various shots of people sanding down edges of new engine parts and drilling holes in them.]
[Shiue appears on camera, holding a part, and speaks: Now we just have to sand this down, sand this down a bit and it’ll be good for the engine. Yep, that’s it.]
[Screen fades to black]
[IU trident appears]
[Words appear: IUPUI Fulfilling the promise]
[Words appear: iupui.edu]
[End of transcript]
Hands-on/gloves-on experience is crucial in the class. The students utilize numerous methods and machines during the semester-long project.
Creating the mold
To cast the flywheel and frame of the engine, the students pack down sand mixed with oil and other binders into a metal pattern. They use a tamper and a large hammer to pound down the sand to a dense shape.
Pour the metal
Bars of metal, known as ingots, are melted down in the lab’s induction and resistance furnaces. The student wears goggles, a heavy shirt and gloves to use the long tongs to extract the glowing crucible of shiny molten metal, which is then carefully poured into a mold. The liquid metal goes into a small hole of the mold. When it comes out of the second hole, it means the mold is full. Flames and smoke shoot up during the process.
Break out the parts
After waiting at least 15 minutes to cool, the molds are broken to reveal the shiny, fresh engine parts. Vincent Shiue, a mechanical engineering senior, said there are some reject parts on occasion, but the success rate is high.
“If the metal isn’t hot enough or if we don’t pour it fast enough, it’ll solidify too early and get stuck,” Shiue explained.
Parts must be perfect
The students then sand down excess metal before utilizing mills, drill presses and lathes to make sure the parts will fit securely. LED screens show measurements down to a 10,000th of an inch. The measurements show where the parts must be machined down further and where holes will be drilled.
“This is full-scale manufacturing gear,” said Ed Herger, a lecturer in mechanical engineering technology. “Most students enter here not knowing these machines but leave here knowing how to make engines. They put in quite a lot of work.”
Air flow
Each engine is tested with an air flow rate of 40 cubic feet per minute at 40 pounds per square inch. The four holes drilled through the frame by the students guide the air through the engine – two holes going horizontally are attached to the air source to push the piston. The other two are for exhaust.
Successful engines make the grade
Students are allowed to make modifications to their engines to improve performance and grades. Top engines usually get to about 4,000 rpm. More powerful rates like that are usually due to students going beyond the original specifications by reducing weight and improving balance on the flywheel.
“It’s as much work as they want to put into it,” Herger said. “I expect they’ll get better and better.”
Students like Shiue are already benefiting from the project’s beginning-to-end process.
“It’s important to know what the construction process is so you know how to design or know what manufacturing processes are necessary to make certain pieces,” Shiue said. “You have to understand all of the steps you have to go through to make the final piece.”
Photos by Liz Kaye, Indiana University
