How to remove the thick coating on the plating rack?
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There will be a variety of unfavorable consequences when the coating on the hanger is too thick. The main ones are as follows. (1) Imprints will appear on the hooks of the plated parts Because the hook becomes thicker at the contact area of the plated part and the hook, the covered surface of the plated part is enlarged, which will affect the normal deposition of the lamellae. (2) The hook is easy to break When the coating on the hanger is too thick, it is inevitable that the coating thickness will be uneven, especially the coating on the contact point where the hook directly hangs the workpiece will be very thin, and the coating around it will be very thick. If you apply force, it will break, and the hanging workpiece will be scattered or broken due to this, and a quality accident will occur. (3) Increase production cost With the thickening of the coating on the rack, its surface area increases correspondingly, the metal on the sink increases, the solution carried out with the rack (workpiece) increases, and the energy consumption increases at the same time. (4) Mutual contamination between plating solutions. The coating on the rack is too thick, the surface roughness of the coating is improved, and the cleaning quality is reduced. The solution adsorbed on the surface of the rack is difficult to clean, which will cause mutual contamination between the plating solutions. When the plating layer on the hanger is removed, the general plating type can be carried out in the same way as the plating removal method on the plated piece of the plating type. The over-thick chrome layer on the chrome hanger is often thicker and it takes a long time to retreat. At this time, it can take advantage of its brittleness and use a hammer to remove it. , The chromium layer will fall off on its own wherever the hammer goes, and sometimes the plating layer will fall off on its own after using a wire cutter. The coating on the racks with galvanizing, cadmium plating, tin plating, black nickel plating, etc. should be used once and then returned once, so as not to contaminate others during the pretreatment process. The plating solution for the plating species. The nickel layer on the steel hanger can be removed by the following process. Nitric acid (HNO3) 1000mL/L Sodium chloride (NaCl) 30~50g/L Temperature 40~60℃ The shortcomings of this process method are the formation of nitrogen oxides, which must be carried out under good exhaust conditions during work, and the removal of water must be prevented from bringing in moisture to avoid corrosion. When removing the nickel layer in a process formulation mainly containing sodium cyanide and sodium m-nitrobenzene sulfonate, it can be carried out at room temperature to prevent the sodium cyanide and ammonia from decomposing too quickly. The precious metal-containing solution returned from the precious metal plating hanger should be properly kept for recycling when necessary. The hanger used for aluminum anodizing must be stripped after using it once, otherwise it will no longer be able to conduct electrical current. The film removal can be carried out in acidic solution or alkaline solution. When the film is removed in the acidic film removal solution, the substrate will basically no longer be corroded, so the service life of the hanger can be prolonged. However, the process is more troublesome, requires a higher liquid temperature, and the film removal speed is slow. In addition to the two types of film removal treatments that can be used, a file can also be used to file the contact part with the workpiece, and the oxide film on this part is filed. It can be used afterwards; (Oxidation film is allowed in the non-contact part of the workpiece). This method of removing the film for some hangers can greatly increase the service life of the hangers. |