First, corrosion operation process

After repairing the printed zinc plate, remove the oxide film on the surface with dilute nitric acid solution of 3Be° to reveal the clear and bright zinc quality. The layout can be clear, must not be too heavy, in order to prevent the micro-text part by corrosion and shrinkage and corrosion off. After cleaning the film, clean the plate with water and apply a layer of anti-pitting liquid.

Hemp prevention solution is 25Be° Arabic gum or sodium nitrate 100g, sulfuric acid 200ml, water 500ml (when using water to 10Be°).

Two, the preparation of corrosion liquid and setting conditions

The formula of the corrosive solution: nitric acid range of 8 -- 11.5Be° (that is, 10.2 -- 14.5%), the amount of domestic additives is slightly more and 700 -- 1000ml, and the amount of additives in the United States, Japan and other countries is 550 -- 600ml less.

According to the American additive instruction manual: Nitric acid is 11 -- 11.5% (8 -- 9Be°) additive is 2.8 -- 3%(1100 -- 1200ml). The temperature is 28℃ and spray corrosion is adopted. In China, stirring corrosion is used, and the use of imported additives to make some adjustments to the ratio of corrosive liquid and operating conditions, in order to suit their own factory production conditions.

In order to save raw materials and plate making quantity, the imported additive is usually used in half quantity, that is, 550-600ml formula. The slope protection problem is solved by raising the temperature without enhancing slope protection force (28-30 ℃) and reducing the number of revolutions of 250-300 revolution.

Use domestic additive dosage, temperature slightly lower 22-25℃, revolution slightly higher 290-350. The time is usually 15-17 minutes. Depth up to 0.6mm, incline Angle of 110-120 °.

Common fault diagnosis

1, side wall pull:

(1) The edge of the text and text is smooth and bright, the slope is big, and the corners of the layout are too acidic.

(2) The edges of the text and text are hairy, gray, small slope, and the corners of the layout are too little acid.

(3) The edge of the text and text is hairy and cut inside, and the layout is gray, which is seriously deficient in acid.

(4) the full version of the scratch, relative time corrosion of shallow and less acid.

(5) less additives in the side wall.

(6) High revolution and low temperature will also cause internal cut.

2, the slope is too large, the small word gap is shallow:

(1) liquid level height (normal blade draft 10-15mm).

(2) High temperature.

(3) Low revolutions.

(4) many additives.

3, layout hemp tablet

(1) The corrosion liquid is too old and lack of acid.

(2) too many additives or short stirring time corrosion liquid is not fully emulsified.

(3) The temperature is too high.

(4) Revolutions are too low.

(5) baking plate temperature is too high, zinc plate microcrystalline damage.

4, layout hemp point

(1) The layout is not clean.

(2) add guoji and acid mixed unevenly, short stirring time (more than 15 minutes).

(3) the action of the upper version is too slow, the downtime is long or the failure of the pitting liquid is prevented.

(4) Impurities in the machine.

(5) The amount of acid is too little, the temperature is too low will also appear small needle-like pitting point group.

(6) the quality of zinc plate is not good, the quality of acid is not good.

(7) the baking version temperature is too high.
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