I created a dedicated fixture for the accelerated lifetime testing of a key new design.
We needed a testing fixture to validate the new design of a key component of our 3D printer. The requirements were that the fixture needed to house our newly designed cutter module in a hot chamber and make cuts of carbon fiber autonomously while monitoring for failure modes and counting cuts. Such a fixture provides valuable insight into the lifetime of our newly designed cutter module and highlights any design flaws that we need to address.
The basic premise of this fixture was to test the lifetime of our new carbon fiber cutter module to see how long the design would last in the 3D printer and give us important insight in the failures we could see in customer’s machines. Regular operation was for carbon fiber (mounted on spools at the back of the fixture) to be pulled a certain length by an extruder motor and then cut. This process would repeat itself until there was a cutter failure or material jam.
The design had several variables to consider. First, the testing environment had to mimic the actual conditions in the printer and be able to maintain at least 80 degrees Celsius while cutting fiber continuously. We also needed somewhere for the cut fiber to go, as carbon fiber falling onto electric heater coils could result in a fire or an electrical short. An added perk was to make the testing fixture interchangeable, so future engineers could replace the modules with other parts to test.
I came up with the design, sketched it all in Solidworks, and used leftover printer parts to get the right electronics I needed. I machined custom hardware, heavily modified an off-the-shelf laboratory oven, and came up with safe methods to mount electronics and handle waste fiber. I used rivet nuts and bolts for fasteners so the design was robust, but easily customizable. All the electronics are mounted on standoffs, safe from the heated chamber and all cables were custom-made and routed in an organized fashion.
This fixture is still cutting to this day with no failures in the cutter modules, even after hundreds of thousands of cuts each.
