After cutting and welding bakery trolley shelves, the tubes and welded joints are always covered with oil and dust. And also around welded joints, the steel will become dark. Traditionally, grinding the dark area by toolings,which will damage the steel and for long term, the grinded area easily will be rusted.To solve above problems, laser cleaning machines are used to clean welded joints without any damages. Besides, to remove oil and dust, ultrasonic cleaning is added.