Before the metal surface is electroplated, in order to ensure the yield of the electroplating operation and prevent oxidation, it must be degreasing treatment before electroplating. According to statistical data analysis, modern electroplating believes that 40% of the unqualified products are from poor pre-plating cleaning. Therefore, more and more electrical quality managers have begun to pay attention to pre-plating treatment.
Due to different material processing techniques and different pollutants such as oil stains remaining on the metal surface, in order to ensure the cleaning effect, when the requirements are higher, special metal parts cleaning agents and cleaning processes need to be used for treatment. For the in-line processing of multiple metal materials, the cleaning process needs to be designed reasonably, which is very important: it can not only reduce production costs, but also improve efficiency and product quality.
At present, most of the degreasing and decontamination processes are random and backward. It seems that the cleaning cost has been reduced, but the other costs have increased, and the total cost has increased. The main reasons for this status quo are: product processing companies do not know much about chemical technology; processing companies only consider the unit price of cleaning agents, and rarely consider the total consumption and cleaning quality.
So how to choose an excellent pre-plating oil stain treatment process? First of all, we must first analyze the source of oil pollution.
Generally speaking, oil stains on metal surfaces mainly come from the following categories.
(1) The corrosion protection of the metal/steel surface produces oil stains
Since metal steel plates are susceptible to atmospheric corrosion, in order to enhance their corrosion resistance during storage, they need to be coated with anti-rust grease when they go out. A typical example is cold-rolled thin steel plates (plates or coils), which are usually coated with anti-rust grease, anti-rust paper or even plastic film. Therefore, cold-rolled steel sheets tend to have more oil and less rust, and thorough degreasing has become the main pre-treatment process for plating. However, through practice, it has been discovered that the anti-rust grease applied by different steel manufacturers is different, and it is difficult to remove the oil after being made. When chemical degreasing, the formula that has a good effect on removing one type of anti-rust grease is better for another type of anti-rust grease. The removal effect of rust grease is not necessarily ideal.
If the metal steel plate material is stored for too long, it will cause the anti-rust oil to dry up, making removal more difficult. Therefore, it takes some brainstorming to clean the workpiece of this kind of material.
(2) Oil pollution introduced by mechanical processing
When machining metal materials such as turning and grinding, some oil will be smeared on the tools in order to ensure the machinability and prolong the service life of the processing tools. For example, the white oil used for electro-engraving before chrome plating, gasoline for plate washing, and copper polishing process currently use oily polishing paste. If the plate is not cleaned before engraving, it will be removed before chromium.
(3) Operation pollution
The stains on the work gloves may also be attached to the metal surface during the turnover, installation of the plate roller, and when the plate roller is manipulated. Sometimes pickling is done first, and the oil film on the surface of the pickling liquid or cleaning water will also be attached to the workpiece.
1. Ultrasonic cleaning:
Process requirements: Ultrasonic cleaning process is adopted, and the temperature is controlled at about 50°C. It is recommended to use a water-based metal cleaner with a dilution concentration of about 10%.
Main function: to remove dust, part of oil stains, processing coolant, hand sweat, inorganic salt, etc. on the surface of the workpiece. Because the chemical liquid is easy to get dirty, it needs to be drained frequently as a pretreatment.
2. Acid degreasing activation:
Process requirements: Use a solvent-based acidic degreasing agent for cleaning, pay attention to cleaning at room temperature, and do not heat the cleaning agent.
Main function: remove the oil stains inside the metal surface, especially the oil stains, alkalis and oxidation passivation layer inside the non-ferrous metal surface, and perform preliminary activation of the metal to remove all kinds of dirt on the surface of the workpiece.
The pre-treatment and cleaning of electroplating is not complicated. As long as you understand the oil pollution and select the appropriate cleaning agent plus the correct operation, the subsequent electroplating process will not be affected.
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