thangi
A six-week project in the fall of 2024
What if children grew up with dolls that looked like them?
Inspired by my continuously growing extended family and a lullaby that my mother and her sisters sang to us growing up, I explored injection molding three-inch dolls.
Materials: Polypropylene, TPU
Challenge:
Design a part or a family of parts that:
maintain some functionality, as determined by the designer
must interact in a geometrically meaningful way with multiple copies of itself and/or fit with an existing part or assembly.
Conceptualization
CAD of body, hair, and clothing
Future Considerations
Originally, I used a combination of Revolve commands to build out the body but as I proceeded to CAD-ing the hair, the body felt proportionally off from my intended design. Separately, I was concerned about the significant shrinkage that would occur when molding the PP body and the inconsistent compounding effect that this would have on the subsequent parts.
Thus, I pivoted to using a serious of Loft commands to build out the parts, final versions seen below. I did this by creating a series of 2D sketches in ProCreate and importing the sketches to Fusion to act as a template for my initial lofts.
Final versions of the PP body (missing the eye cavities)
Fabrication
Settling on form…
I drew inspiration from Funko dolls, as I loved the exaggerated sizing of the characters’ heads.
Determining the structure of the doll and the process of overmolding went hand-in-hand. Color choice, material choice, geometry, shut-off locations are some of many factors that influenced the process and eventually the CAD of the doll.
Hair, shut-offs located at the shoulders
Tooling CAM (select sides of select molds)
CAM of Side A of the Mold for the Doll Body
Balance: of aesthetic and functionality. The CAD looks beautiful, but a significant portion of the flash issues would have been remedied if the body’s geometry was simpler.
Efficiency: Ejector pins to eject the body would have greatly reduced molding time and likely aided in the shrinkage issue.
Dress: an offset of the body as it was designed clothed.
CAM of Side B of the Mold for the Doll’s Hair
During the hair molding process, flash consistently occurred because the PP body parts shrank unevenly. To address this issue, I created silicone "masks" that could be placed on the PP parts before molding to fill the gaps between the mold and the plastic component, preventing flash formation.
Since the clothing was simply an offset of the body geometry, there wasn’t a clear shutoff location for the dress, and first shots yielded a significant amount of flash. Due to time constraints, reviewing and adjusting geometry was not an option; thus, I modified the mold to remove any “knife edge,” and modified dosage volume, amongst other factors in the molding program. Despite these efforts, however, I was not able to get parts with consistent clothing.