AFSD Wire Feed Mechanism

The previous mechanism used two rollers to pinch the wire. When the rollers were spun using stepper motors, the wire would be pushed downwards through a tube at a constant rate. However, the mechanism would often jam when using Dauber to conduct a deposition, causing the pulleys to skip. 

By using a microscope to analyze the wires after they had been fed through, I discovered that the teeth on the rollers were deforming the wire a significant amount. This was creating excessive friction within the tube, opposing the force output of the stepper motors until the timing belts they drove skipped, and interrupted the deposition. 

To resolve the deformation issue, I created and manufactured a new roller design that had threads with an increased pitch, decreased thread angle, and increased depth. 

My reasoning for increasing the pitch and decreasing the thread angle was that it would decrease the total volume of threads that dig into the wire, meaning less volume of the wire should be displaced and deformed. I also increased the depth of the teeth to compensate for the reduced force output capacity caused by the changes. 

In order to validate whether the new design increased the consistency of force output and decreased the incidence rate of jams, I designed and 3D printed a specialized testing setup. This allowed me to measure the force output while continuously feeding wire, mimicking the conditions of a deposition. 

This testing showed that peak force output decreased 9.30%, but this force was able to be maintained for 10 minutes, at minimum. This is opposed to the original roller design, which could only hold peak force output for less than a second before the timing belt skipped. This longevity of force production more than makes up for the slight dip in peak force output in terms of significance for deposition success.