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Purdue School of Engineering and Technology

Purdue School of Engineering and Technology

Make and start your engines with Mechanical Engineering Technology program

November 14, 2018

The process of making engines in this mechanical engineering technology class requires students to pour molten metal to cast engine parts before machining them. Photos by Liz Kaye, Indiana University

The process of making engines in this mechanical engineering technology class requires students to pour molten metal to cast engine parts before machining them. Photos by Liz Kaye, Indiana University

BY TIM BROUK

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."


From molten metal to working engines, the manufacturing processes class has students cast their own engine parts. Video by Tim Brouk, Indiana University

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."

Original story here.