My capstone team was tasked with redesigning a powder dispensing system for an enormous selective laser sintering (SLS) 3D printer.
The original hopper system clogged often, leaked powder all over the lab, and did not dispense a reliable amount of powder:
We came up with 3 prototypes, shown below. The first matched the original hopper design. The second was a modification of this design that reduced the gravitational packing force on the powder to mitigate clumping.
Our third design used a sliding plate mechanism to reduce the packing force as well as prevent leakage.
Our experiments highlighted some of the benefits of the sliding mechanism, so we decided to pursue this design. After some engineering analysis, we decided to actuate the sliding plate with a rack and pinion on a simple PD controller.
Since the original hopper had issues with powder clumping, we added a clearing mechanism which would punch out any powder stuck to the sliding plate:
Our benchtop model was succesful, dispensing uniform amounts of powder and logging useful data, such as mass of powder drops and motor current.