Summary of Manufacturing & Assembly of Yo-Yo Parts

Core: This is an injection molded part that will house the other two pieces of the yo-yo. It will make up the body and the general shape of the yo-yo. We will be using a mold that is machined to 2% larger in order to account for plastic shrinkage. The inner diameter will be designed to be slightly smaller than the outer diameter of the ring in order to ensure a tight snap fit. This will allow for us to create sturdy, longer-lasting parts. Ring: This is a ring-shaped injection molded part that will be press fit on the inner edge of the core and hold the thermoformed pieces in place. Its core mold will have an extrusion of 0.15” with an inner diameter of outer diameter of 2.05” to account for shrinkage (about 2% of the original 2” dimension and +.01” to allow for a tight press fit with the 2” diameter of the core). With these design considerations in mind, the ring should be able to retain the thermoformed radioactive and biohazard designs in the core. Radioactive & Biohazard Designs: These are thermoformed parts that will sit on opposing faces of the yo-yo. Their molds will have an extrusion of 0.075” at a diameter of 1.5” to fit it into the ring, and a final extrusion composed of the design at another 0.075” to make the symbols visible. The pieces will each be of 2” diameter. Once the plastic has its shape, we will spray paint the extruded sections to give the yo-yo more color contrast. The designed thermoformed parts will be fit into a 2” diameter inset in the core and secured in with the injection molded ring that is press fit into the inner rim of the core piece. Assembly: In each core, we will place the thermoformed piece and center it into a 2” inset, and then press fit a ring around its edge to hold the thermoformed piece tightly into the yo-yo. The ring will be press fit between the cylindrical extrusion of the thermoformed part and the inner diameter of the core. The two cores will each have one nut to be able to screw on an axle to wind the string and hold the two cores together. One side of the complete yo-yo will have the biohazard design, and the other will have the radioactive symbol.