How to prevent precision castings from turning black

The methods to prevent precision castings from turning black are as follows:

Surface cleaning. After die-casting and machining, corrosive substances such as release agents and cutting fluids will remain on the surface of the casting. If it is not cleaned thoroughly, it will accelerate the blackening. Passivation treatment is used for this, including pre-degreasing, degreasing, water washing, pickling, etc. Good cleaning can reduce the risk of oxidation and blackening of the casting.

Process control. If the pressure during die-casting of the casting is not enough, the density of the workpiece will be reduced and capillary pores will be formed. The capillary pores will easily turn black after absorbing water and being oxidized. Therefore, the speed and intensity of die-casting of the casting need to be controlled.

Workers should wear gloves when working. Avoid direct skin contact with cast aluminum parts. At the same time, pay attention to drying the product to prevent water stains from remaining on the surface of the object.

Storage and packaging. Place the castings in a ventilated and dry environment, avoid direct sunlight. Use open-hole packaging to facilitate the evaporation of water droplets, and add moisture-proof agent in the packaging box.