It is not easy to get nano size powder by planetary ball mill, normally effect of wet grinding is better than dry grinding. The main factors affecting the particle size of ball milling.
1. Material of the milling tools (milling jars and balls). Milling tools selection depend on sample characteristics. Normally, the milling jar material must be harder than the material to be milled.
2. Milling balls/sample/solvent ratio
3. Milling ball size
4. Working time
5. Grinding speed