make into mince, cut
劖 centers on cutting something into small pieces: mincing, chopping, or carving away material.
劖 combines 毚 (a phonetic component with uncertain original meaning) and 刂 (knife), suggesting cutting or mincing with a blade.
The left side 毚 looks like a pile of small pieces, and the right side 刂 is a knife. Imagine a knife mincing a pile of ingredients into tiny bits.
For サン, picture a chef mincing ingredients under the sun: sun -> サン, and the knife 刂 chops everything fine.