Zinc aluminum die-casting is a type of component formed by powder die-casting with zinc as the main component. This type of component has a dense surface layer on the outside and a dispersed porous structure on the inside. Acid degreasing agents cannot be used, only alkaline degreasing agents can be used for degreasing.

Most zinc aluminum parts require copper nickel chromium multi-layer coating, which has high requirements for decoration. Before degreasing, it is mechanically polished. So removing wax (rich in white wax in polishing paste) is the first step, followed by chemical degreasing and electrolytic degreasing.

Because the melting point of white wax is above 70%, in order to emulsify white wax, the temperature of the wax removal water must be above 70 ℃ to be effective. In the past, people only used ordinary chemical degreasing solutions to increase temperature for wax removal. This method takes a long time and has low power. Nowadays, there is a specialized supply of wax removal water, which shortens the time and achieves better results. If ultrasound is used, the effect is very good. Usually, wax removal water only removes wax without degreasing, and chemical degreasing is also required. Zinc alloy has strong chemical activity, and the alkalinity of chemical degreasing solution should not be too strong, otherwise it will corrode the surface. The temperature is usually controlled between 50-70 ℃ for 3-5 minutes. The products available in the market also have degreasing agents that combine degreasing and wax removal, and work well with ultrasonic waves.

The composition of electrolytic degreaser for zinc alloy parts is similar to that of chemical degreaser. But it is necessary to be rich in chelating agents in order to use it. During electrolytic degreasing, zinc alloy die castings should be placed at the cathode for degreasing, with a temperature of 50-70 ℃, a current density of 3-5 A/dm2, and a duration of 1-2 minutes.

When selecting the dual process of wax removal and degreasing, a brown corrosion film may sometimes appear on the surface of the die-casting under ultrasonic effect. This degreaser is not suitable for use. The degreaser specifically designed for zinc die castings should be replaced. This should be given special attention.