Above: The final coin casting produced by the Investment Casting “In a Box.”


I asked them, “What made you want to create this?” I was surprised to hear the answer. “We really wanted to increase the awareness and


interest of younger generations in the manufacturing sector. I feel this is something that is fading and not appreciated to the degree that it should be, because manufacturing uses a number of advanced technologies, including investment casting. And manufacturing is always changing, incorporating new technologies, and trying to get better to attain that competitive edge. But many people in the industry are retiring or getting ready to retire, and yet that knowledge isn’t being passed on to young people or preserved in any way. By getting more people, especially high school and college-aged people, interested in this industry and in manufacturing in general, we hope to alleviate that skills gap,” Greer explained. I found it interesting and inspiring to hear that these students were just as concerned about the future of investment casting as our industry leaders. Driving to the airport that afternoon to return home,


I passed a sign that read, “Gerald R. Ford Airport Viewing Area” and I turned in. I watched the airplanes land and take off while wondering how many investment cast parts were on each plane. Then I thought about the students who might benefit from seeing the Investment Casting “In a Box” metal casting demonstration. Maybe its the high school student who never considered a career in manufacturing. Maybe its the engineering student enamored with new technology. Or maybe its the student who sits back in wonder watching airplanes take off. And maybe Investment Casting “In a Box” just might open a door to their future.


For more information helping the Investment Casting


Institute develop an Investment Casting “In a Box,” for ICI Member use, contact Joseph Fritz at jfritz@investmentcasting.


Above: An induction furnace with a custom built lifting mechanism was created by WMU students final project.


So How Did They Do It? The students evaluated melting properties of several 3D printer plastics but ultimately selected an industrial investment casting wax deciding that its melting point of 77ºC would be a easy temperature to achieve for pattern creation and dewax. Their mold design, created with 3D CAD software, was an


aluminum coin pattern chosen for its simplicity and size with three components: a cavity, ejector pin and bottom surface. After creating a sprue pouring cup from paper cone cups, the students soldered the wax sprue to the edge of the wax coin. This wax pattern creation would have to be done prior to a metal casting demonstration. Next, they considered the ceramic shell material. Their


selection would need to meet the three hour time limit requirement. Comparing a plaster of Paris mixture, a pre-mixed industrial slurry, they finally decided on a rapid investment casting powder and binder with a set time of 20 - 30 minutes. The students then chose a box oven for the the dewax and


curing process. The oven had to meet electrical requirements for a standard outlet, had to be portable and would meet their maximum temperature requirement of 620ºC. After testing a time frame for their shell creation, they


found that a final schedule of 55 minutes would be all that was needed to allow for a shell building process that included two coats of slurry, a dewax and a curing session. Chosing their metal, the students looked at tin, aluminum,


and copper but finally chose zinc for their purposes because of its availablity, the low cost and the achievable melting point in their induction furnace. An alumina crucible was picked because it could


withstand 1750ºC, was small enough to fit in the induction coil, but large enough to hold the 10mL required to fill their shell. With safety in mind, the students then designed a four bar slider mechanism with an insulated ceramic base to lift the crucible into the coil. Finally they used a sand filled basin to secure the shell and


pour the molten metal with a cooling time of 10-15 minutes. The finishing process consisted of breaking off the shell and sprue to reveal the final casting.


December 2018 ❘ 25 ®


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