What is the quality standard of copper plating before electroplating on the drum of electric engraving plate making? (Foshan Kaijie Plate Making)

(1) The surface of the copper layer is smooth, without sand holes, oil spots and peeling.

(2) The thickness of copper layer is generally about .1mm, and the copper layer is too thick, resulting in unnecessary waste; The copper layer is too thin, and it is easy to inject when electric carving.

(3) The hardness of copper layer should be controlled at 18 ~ 22 HV, which is too high, and it is easy to be injected during electro-carving; The hardness is too low, and the dot is easy to deform, which is not conducive to the reduction and reproduction of tone.

(4) The chamfers at both ends of the drum are smooth without burrs or pits.