Rotary Powder Feeder Mechanism

This project is a modification of the CSAM (Cold-Spray Additive Manufacturing) machine utilized at the Burlington Innovation Campus. The objective is to increase the consistency, efficiency, and component life of the current feeding mechanism. If these metrics can be qualitatively achieved, the lab can produce/repair parts quicker and at a higher quality, while suffering less from powder loss. This may seem trivial, but vials of powder can cost thousands of dollars: every milligram is worth using.
The current design utilizes rotation to agitate powder into holes at the bottom of a drum. A high pressure line of gas is blown through a nozzle with a gasket attachment. When the gas line and the holes align, the mixture is pushed through into a receptor and deposited into an electric heater. Powder loss occurs in all openings within the chamber; Volume remaining in the drum also affects the packing effectiveness of the powder, leading to slower feeding towards the end of spray cycles. Smaller sized powders are more likely to escape the assembly line or clump while abrasive powder are more likely to scratch parts. Interfacing parts and openings are difficult to seal, most gaskets or soft components wear quickly, the size of the holes at the bottom must be large enough for the powder to fall in but not through. Testing a new method, or addressing these problems is the heart of this issue.

Two modifications are being tested, one as a retrofit of the current components and the other as a centrifugal feeder. This sample focuses on the design for the geometry of the bowl.
A rotating feeder utilizes the centrifugal force on an object to toss it out of the radius of the mechanism. We can analyze the force on any particular object on a slope and try to derive a surface profile that will allow that object to be weightless. For this specific balance, we look towards the centrifugal force on the object and it’s acceleration due to gravity. By matching the appropriate force and creating a matrix of radius and rotation speeds, we can now set our boundary conditions. The canister must be confined within x inches in height and .0625m in radius. We can set upper and lower bounds to the rotations that our motor can provide and polyfit equations to the profiles we want to test. Next we will 3d print these profiles and test their powder outputs before making further changes.

A matrix with the y-axis as the RPM above 20 and the x-axis as the radius from center. Each cell holds the value for the theta required at any point.