How to degrease zinc-aluminum die castings?

Zinc-aluminum die casting is a powder die-cast zinc-based component. The surface of this part is a very dense surface layer, inside it is an evacuated porous structure. Acid degreasers cannot be used, but only alkaline degreasers can be used for degreasing. Most zinc-aluminum parts require copper-plated nickel-chromium multilayer coatings, which have a high degree of decorative requirements. Before degreasing it is mechanically polished. Therefore, the wax (polishing paste contains paraffin) is on the front, followed by chemical degreasing and electrolytic degreasing. Since the melting point of the paraffin wax is above 70%, it is effective to emulsify the paraffin wax except that the temperature of the wax water is higher than 70°C. In the past, people only used ordinary chemical degreasing fluids to raise the temperature to remove the wax. This method is long and inefficient. Now there is a special supply of dewaxing water, the time is shortened and the effect is better. If you use ultrasound better. In addition to the wax water, except that the wax is not degreasing, it is necessary to perform chemical degreasing again. The chemical activity of the zinc alloy is very strong, and the alkalinity of the chemical degreasing liquid cannot be too strong, otherwise it will corrode the surface. The temperature is generally controlled between 50 ~ 70 °C, time 3-5min. The products supplied on the market also have degreasing agents that degrease and remove waxes, and work well with ultrasonics. The electrolytic degreaser composition of the zinc alloy part is similar to the chemical degreasing agent. However, it must contain a complexing agent before it can be used. In the electrolytic degreasing, zinc alloy die castings should be placed on the cathode degreasing, the temperature at 50 ~ 70 °C, current density 3 - 5A/dm2, time 1-2min. In the selection of the wax and degreasing two-in-one process, the surface of the die-cast product under ultrasonic conditions sometimes produces a brown corrosion film. This degreaser should not be used. The degreaser for zinc die castings should be replaced. This should pay special attention