Sand Making Machine Working Principle:
When it begins work, the materials fall direct into the rotary wheel which is rotating in a high speed, and the materials will strike high-speedily and smash high-densely with the target stones which are around the rotary wheel in a umbellate form. After the striking, the materials and the target stones will move in eddy current between the rotary wheel and the main case. So, the materials and the target stones shall hit, grind, crush and then be discharged from the lower part. This kind of process will repeat untill the materials become the required particles.

Sand Making Machine Characters:
(1) Less wear: There is thick material-layer below when the materials and the target stones hit each other. So, they cannot touch the frame, and the steel liner is unnecessary.
(2) As to the few easy-worn parts, they are made of ultrahard material with high wear resistant. Besides, their sizes are small, weights are light, and they are easy to be replaced.
(3) High degree of purity: This machine employs the self-collision of the materials as the main process of crushing. Therefore, the discharged material is pure as much as possible.
(4) Adjustable granularity: Adjusting parts of the machine makes the proportion of the required particle size increased significantly.

http://www.pe750.com/Crusher/Sand-Making-Machine.html