In the electroplating process, the bad phenomenon of spraying paint on the coating often occurs, which is due to the oil on the surface after plating, resulting in poor adhesion.However, when parts are electroplated, pinhole often occurs after plating. Today we will talk about pinhole caused by improper pretreatment and treatment solutions.
Frequently asked questions:
(1) incomplete removal of oil from parts or improper storage during machining; dust falls on the surface and is kept for a long time. The dust is mixed with oil and sticks together, which is difficult to remove and clean. As a result, small oil spots are formed, and bubbles are retained on the surface to form pinholes.
(2) when the parts are polished, the abrasive and polishing paste are embedded into the micro-pit on the surface, which is difficult to be cleaned, and the pinholes are not deposited on the coating layer.
(3) the parts are not completely cleaned by pickling or have been corroded for too long, and there are carbon rich points on the surface, so the plating layer can only be deposited around these non-conductive particles to form pinholes.
(1) the reasonable pretreatment process, to ensure the quality of pretreatment, the pretreatment process for: parts on to chemical degreasing, hot water washing to water washing, pickling - two water washing - electric lift oil to hot water to wash, wash water - weak corrosion - two water washing, strictly carry out operation procedures, strengthen bath maintenance management.
(2) the surface of the parts is not clean before plating. If there are oil dirt particles and other non-conducting particles, they stick to it.The brush that can be wetted with alkaline water is brushed, undertake electric discharge is oily again, small part had better undertake roll finish processing.
(3) when there is oil layer on the liquid surface of chemical oil removal or electrochemical oil removal tank, it shall be salvaged in time.Care should be taken to remove the polishing paste thoroughly after grinding.
(4) please control the pickling time. Once the rust is removed, it should be removed and cleaned immediately.In order to prevent over-corrosion of parts, a certain amount of corrosion inhibitor should be added to the acid wash solution.