In electroplating, the purpose of pretreatment is to remove the dirt and impurities on the surface of the workpiece and make it a suitable active surface for electroplating. The reason for the poor quality of electroplating is that the pretreatment is not good. And the pretreatment is not good, most did not use ultrasonic cleaning equipment. At present, the electroplating industry does not know the actual application of ultrasonic cleaning equipment, so it is necessary to talk about its use.
Ultrasonic pretreatment: in the pretreatment of electroplating must be based on the actual situation of the workpiece, using an appropriate method for effective cleaning. Metal substrates are generally divided into stamping parts and die-casting parts. The oil on the stamping part is the general stamping oil, which is easier to clean because of its high density. Generally available pickling, electrolysis, etc. Ultrasonic cleaning is more effective depending on the manufacturer. And zinc, aluminum, copper, etc. Die casting is more difficult to clean. Due to the addition of various elements in the die casting, in addition to the molding, drawing, rolling, cutting, polishing process must also use a variety of oils, such as oil, polishing oil. For ultrasonic washing machine, oil can be easily removed. But polishing oil cent is butter white oil, green oil, this is more difficult to remove. Therefore, the appropriate ultrasonic cleaning equipment and cleaning fluid must be selected. Copper as a material for a triangle valve, after polishing cleaning, polishing oils for white oil, butter, bath temperature is 70 ℃, when ultrasonic power is 1.0 W/cm, in ordinary cleaning solution 3-4 minutes to wash, get the right plating surface. But when polishing oils for green oil, must immerse first, then effect of degreasing cleaning fluid (in addition to the company's German S104, bonanza wax water, etc.), the bath temperature is 70 ℃, when ultrasonic power is 1.5 KW/cm, need 4 to 5 minutes to get the appropriate plating surface. If be zinc alloy part, choose alkaline stronger cleaner fluid commonly, the temperature is in 65℃-75℃ between, in 2 minutes (according to polish time to decide) inside can remove polish oil. In order to effectively avoid the plating process with finger print on the surface of workpiece, our company developed directly linked with the inputting type ultrasonic cleaning machine, can effectively improve the efficiency of solving the workpiece in the cleaning of rubbing against each other in scar, avoid the secondary pollution and other issues, after cleaning has been widely spread, and obtained user electroplating industry recognition.
After understanding the types of substrate and oil stains, it is necessary to understand the choice and relationship between ultrasonic power and frequency. The ultrasonic frequency is generally between 20 and 100KHZ. Generally, low frequency and medium power ultrasonic cleaning equipment (such as frequency 25-28KHZ and power density 1W/cm) is used for the pretreatment of common workpiece.
Because low frequency than high frequency in the medium is easy to generate cavitation, for the shape of simple, not very precise workpiece, this kind of cleaning machine can meet the requirements. It is characterized by loud noise and cheap price. For some of the higher precision of the workpiece, is generally used for high frequency (40-68khz), high power ultrasonic cleaning machine. Therefore, the cleaning machine for cracks, gaps, deep holes, blind holes and other complex surface cleaning effect is better. But the purpose of ultrasonic cleaning is to clean only where the solution arrives. That is to say, to avoid deep holes, blind holes in the air, and to pay attention to the fall of impurities, oil drift and treatment cleaning is not in place.
Ultrasonic post-treatment: although after the workpiece plating after the rinse, but some more complex workpiece, especially there are gaps, deep holes, blind holes of the workpiece (such as glasses spring leg) can not play an ideal role. Only by using ultrasound to remove residual electroplating solution in gaps, deep holes, and blind holes. Generally in this respect can choose the frequency is slightly higher, the power density is general ultrasonic cleaning machine.