After learning practicing design for injection molding on the software side, I set out to find a way to learn more about injection molding by doing the process first hand. Fortunately, Techshop offers an injection molding course and I was already planning some time in San Francisco - the manufacturing stars aligned!
This is a safety and basic use course. It afforded me an opportunity to work with pre-made molds designed for injection molding. Examining the mold gave me a good appreciation for the problem solving that goes into all the prep work of injection molding. The time and effort goes in up front and once the tooling is completed and the early batches prove successful, creating a small batch production run of your design is pretty efficient. 3D printing is somewhat the opposite.
I actively want the process to not go smoothly during my workshop learning a new tool. I want to see things break so I can learn how to debug and see someone more experienced verbalize the mental checklist he or she uses to evaluate the tool. Few of my projects with new tools start by everything going exactly as I planned, as demos often seem to during a class. The injection molder didn't disappoint in this regard. It was misbehaving beautifully.
We used polypropylene for this exercise. Another Techshop member left a mold he was done with for us to learn on - a mold for creating small stands for a board game he's making. The first several attempts shot some of the hot polypropylene into the mold but despite using the right amount of material, we weren't seeing completed parts. "Short shots." A few attempts even had much of the polypropylene extruded before the top of the mold. We adjusted the pressure, the time allotted for injection, ran polypropylene through into a catch cup to try and clean the nozzle, and ultimately realigned the upper platen which altered whether the mold was level. This last bit was successful and we each took turns operating the machine to create our own set of eight pieces. Neat to hold something that feels real and not just a prototype.
What's next? I got to explore one of Proto Lab's Demo Molds which got me thinking more about the design that goes into creating the mold. A friend also recommended this resource as well as Proto Labs for more reading on design for injection molding. I'm already looking at so many objects differently as I try to imagine how their molds must look.
I highly recommend Techshop's Fabrication courses to anyone looking to learn more about these methods or for anyone who has a project and needs access to tools. Good people and a great space to work in.
What are other resources or tools to learn more about this subject?