to make a piece of metal flat and smooth by hitting it with a hammer (= a tool consisting of a heavy piece of metal at the end of a handle) or pressing it between rollers (= tube-shaped objects)

Professionals planish metal sheets to make car wings, petrol tanks, and aeroplane bodies. 专业人员采用精轧工艺用金属板制作汽车轮胎挡泥板、油箱和飞机机身。