The flap disc has fan function, which can avoid damaging work piece by burning and keeps sharpen constantly. And It is suitable for grinding rim or polishing the plane, curved surface, deep hole, lacelike and other irregular surface, on metallurgy, airplane, auto, ship, hardware, mold, handicraft, and jewelry. It is also suitable for fine polishing metal and non-metal such as copper, iron, aluminum, stainless steel, rubber, plastic, wood, glass, and stone. It is suitable for grinding complicated curved part too