As seen in the figure to the right, the new SLS powder entering the trough is cooler. This obstructs the thermal uniformity significantly when printing and had to be addressed. 

Since most SLS 3D printing powders are insulative, achieving thermal uniformity is challenging.

To test this solution, the following benchtop rig was built and used for testing. It automatically logs powder flowrate and exit temperature.

This solution is not preferred. Most SLS powders are naturally insulative, meaning the center of powder in the tube could not effectively transfer heat. This led to powder exiting the tube with poor thermal uniformity and below the target setpoint temperature.

The powder mixing benchtop apparatus is another concept for increasing thermal uniformity. As seen in GIF to the right, different color SLS powders model the hot and cold powders for qualitative analysis