Injection molded Ducks
Injection molded Ducks
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Design for Manufacturing
Fall 2024
Design for Manufacturing
Fall 2024
The Goal:
The Goal:
Creating an injection-molded toy that can be mass-produced.
For this project, my group and I created injection-molded duck keychains for people to fidget with and play with. We also wanted to try using a different material besides ABS or polypropylene for our injection-molded toy. We decided to use TPV, a rubber-like plastic that gave the part a squishy feeling, as opposed to the other plastics available for this project.
Main Design Requirements:
- Create at least 5 assemblies of parts that combine to create a toy
- Make it cute and cool at the same time
Skills Developed:
- CAD skills with manufacturing in mind
- Experience with draft and flow analysis
-CNC Mill / Tormach Experience
- Injection molding experience
- Materials Science
- Designing for mass manufacturing
The pictures on the right are some CAD images from SolidWorks. The top left is a model of the duck. The top right image is a screenshot of the flow analysis conducted in SolidWorks. The bottom left is an image of the undercut analysis done on the duck. The bottom right image is the picture of the aluminum blocks in which the ducks will be cut into. This image also contains the sprue and the other components in that the plastic would follow when trying to fill in the cavity of the mold.
Video of running the Tormach to create the mold of the ducks:
Some challenges from this project include the following:
- Dimension considerations
The original design of the duck was created in TinkerCAD, meaning that the duck was created without dimensions in mind. This created issues when we were trying to figure out how the duck would be manufactured, along with scaling issues when changing different CAD softwares. Even though the original design was created in TinkerCad, we had to conduct analyses of the duck with SolidWorks and then create the CAM for the mold in Fusion360.
We also had problems with the model itself. The original design of the duck had eyes that were not manufacturable, along with other aspects of the duck that did not allow for manufacture. This was specifically highlighted in our draft analyses. Only after changing the shape of the duck to fit with the draft analyses and changing the eyes to be physically possible to manufacture were we able to move forward with our creation.
- Dimension considerations Part 2
The size of the duck ended up being an issue later on in our process of creating the ducks. Because the injection mold machine in our shop can only handle a small amount of plastic, the volume of the mold matters. Unfortunately, the volume of our duck mold was on the higher end of the injection mold machine's capabilities, which meant we would potentially run into issues when we shot plastic into the mold (which we did run into).
- Injection Molding issues
Our injection molding machine was a bit unreliable, and this was seen multiple times while we were shooting plastic into our molds. When we were trying to shoot plastic into our molds, we were experiencing shooting times from 5 seconds all the way to 60 seconds. This was bad considering that the max our machine should go to is around 10 seconds. We were also experiencing trouble with shooting plastic to begin with, as we had multiple times where we would press the injection button, and barely any plastic was shot out. We were able to fix this by plugging the second duck mold with a made duck and just injection molding one, but this was not ideal since we wanted to make two ducks at once. We also fixed the plastic undershoot problem by letting the chamber of the injection molder (that holds the nurdles/pellets) heat up for a longer time, making sure that the middle of the chamber gets melted as well.
Results:
Results:
Overall, the ducks ended up looking really well, and the ones that were fully injection molded were able to house the key chain loop. This achieved our goals, and we were able to make three ducks out of TPV, which matched the number of people in our group, so each of us got our own TPV rubber duck.
I wish that we could have had more reliable shots with the injection molder so we could have made two ducks at the same time, but having one complete duck after blocking the second duck seemed to line up with the results of the flow analysis.
The following is a cost analysis of how much money it would take to create each duck.Â
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