What is the process of screw pickling?

Update:13-01-2021
Summary:

The screw wire needs to be processed before it can be p […]

The screw wire needs to be processed before it can be put into screw production. The purpose of screw pickling is to remove the oxide film on the wire surface and form a phosphate film on the metal surface to reduce the wire drawing and cold heading forming process. For mold scratches, what is the process of screw pickling?
1. Pickling: invade the entire disc into three hydrochloric acid tanks with a concentration of 20-25% at room temperature for several minutes;
2. Clean water: remove hydrochloric acid corrosion products on the wire surface;
3. Oxalic acid: increase the activity of metals to make the film produced in the next process more dense;
4. Coating treatment: the disk element is invaded into the phosphate, the steel surface is in contact with the chemical treatment liquid, the steel is dissolved to generate insoluble compounds, and it adheres to the steel surface to form a coating;
5. Lubricant: Since the friction coefficient of the phosphate film is not very low, it cannot give sufficient lubricity during processing, but it reacts with metal soap to form a hard metal soap layer, which can increase its lubricating performance.

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