Yo-yo Molds

We have designed and machined the molds that will create yo-yo. Below, we describe the mold for the orange body of the yo-yo. 

Orange Body

Core Mold

Description: The core mold forms the orange pin-wheel pattern, which snap-fits with the black retaining ring to form a black and orange checkerboard exterior design. (solidworks model below)

Core Mold Manufacturing Process: First, the lathe will create the general shape of the core mold. Next, the shape of the flanges will be created using the mill. A runner will then be milled.

 

Cavity Mold

Description: The cavity mold gives the back side of the body its rounded shape. (soildworks model below)

Cavity Mold Manufacturing Process: First, using the mill, the ejector pins will be drilled into a blank mold. Then, the lathe will carve out the hollow shape of the inner side of the yo-yo. Next, the shafts to hold the nuts in place will be machined on the lathe as well. Finally, the gate will be filed in by hand.

The complete Process Plan for both molds can be found here. 

Justification for dimensions: After measuring molds and their respective parts from completed yo-yos (a chart can be found here), we were able to figure out how to account for shrinkage when deciding the dimensions of our molds. A 0.5 inch shrinkage was estimated for a final outer radius of 2.45 inches, resulting in a cavity mold with an outer radius of 2.50 inches. A drawing of the cavity mold can be found below. It was assumed that circumferential shrinkage would not occur. 

The Manufacturing Time for our yo-yo can be found here and below.

Justification for the described machining times can be found here.

The total machining time for the molds has more than doubled since the initial manufacturing time submission (2 weeks ago) from .5 hours to 1.3 hours. This is due to changes in the machining process of many of our parts including the black cavity and orange cavity. The increased time is also a result of additional time needed for milling injector pins, runners, and other details that were not included in the initial plan. 

The time needed to make revisions to the initial milling/lathing of the molds was unaccounted for and has shifted our team schedule. However, to account for this shift, we have made more lab appointments so that are caught up by the end of this week and to ensure that all deliverables are completed on time.

Here are some pictures of the manufactured molds:

We may have to remachine the connection between the black cavity mold runner and sprue hole. Also, we might want to add a slight draft angle to the thermoform mold for easier removal.

Here's a picture of all of our injection molds in a row. Can't wait to start seeing some plastic parts come out!