HOW DOES ZINC ALLOY DIE-CASTING OVERCOME PLATING DEFECT SKILL?

How does zinc alloy die-casting overcome plating defect skill? Electroplating of zinc alloy die castings is more difficult than that of other substrates. This is because the chemical stability of zinc alloy is poor, easy to be corroded in acid and Alkali solution, and there are some defects such as bubbles, cracks, pinholes etc. . The methods to overcome the defects mainly lie in the pre-treatment, such as blank inspection, mechanical polishing, degreasing, etching, activation and pre-plating, etc. . Zinc alloy die casting 1, blank check, blank check before plating, is an important step to ensure the quality of zinc alloy die casting electroplating. The zinc alloy die casting has some defects such as gate, Flash, horizontal line, Burr, knot and so on. To this need to carry out strict inspection, to prevent defective products into the electroplating process. It can reduce the rework rate and production cost to eliminate the rough parts which can bring quality problems to electroplating after mechanical polishing or leveling. 2, mechanical polishing, polishing tool should be a softer elastic wheel. As the zinc alloy die-casting soft texture, so must use white cotton cloth made of grinding wheel (its working surface with emery) for polishing. When the workpiece is pressed to the grinding wheel working surface, the abrasive particles can be inserted into the wheel, so that the cutting ability of the abrasive particles can be weakened, so that the geometric shape of the workpiece will not change and the surface will be smoother after grinding. It is not suitable to use the abrasive wheel to Polish directly, to avoid exposing the bottom of the workpiece (the bottom is porous, loose structure) , to remove the dense layer during grinding, and to prevent the soft metal from sticking to the grinding wheel, to reduce the smoothness of the ground surface. Therefore, the grinding wheel working surface needs to be coated with red polishing paste, so that countless abrasive particles are covered by polishing paste, grinding performance can be weakened, resulting in a more smooth and smooth surface. The force of the working face pressing on the grinding wheel should be small and uniform. The surface dense layer of zinc alloy die casting directly affects the quality of electroplating, so it must be protected when polished. If the Polishing Operation Force is too large, not only will destroy the dense layer, but also will produce a lot of friction heat, and even scorch. The purpose of polishing is to further remove the micro-defects and improve the smoothness of the surface of the substrate. And the polishing wheel is softer, if the flannelette wheel. The speed of the polishing wheel should be higher than when polishing better, and with white polishing paste. White polishing paste in calcium oxide and magnesium oxide fine particles and round, non-sharp edge, very suitable for zinc alloy die-casting and other soft metals and require high finish of the fine polishing. When polishing the workpiece to be lightly polished, the amount of polishing paste to be used, that is, less frequent use is appropriate. If the amount of polishing paste is too large, in addition to waste, but also stick to the work of the groove or gap, in addition to oil difficulties. But polishing paste should not be too little, otherwise in the absence of polishing paste when easy to pour light, so that parts of the surface overheating and pitting, affect the quality of electroplating. When necessary polishing can be divided into two processes, that is, first with red polishing paste, then with white polishing paste (or powder) fine polishing. It should be noted that polishing, polishing can not destroy the dense surface of the substrate, exposed porous layer, otherwise it is difficult to get good adhesion coating. 3, Zinc Alloy die casting oil removal, workpiece after grinding and polishing, should be cleaned as soon as possible with organic solvents. Otherwise, a long time (more than 24