When die casting parts made out, in order to improve the strength and hardness of the products, we usually need to do some surface treatment to achieve these effects; these treatments are what we often call post-treatment, in general, the post-treatment contains anodizing, shot blasting, powder coating, baking paint, oil spraying
Why we need to do die casting post process？
After die casting; for instance; to improve the corrosion resistance of parts; wear resistance; assembly; prolong the life of the die casting parts; besides to make colorful of the surface; we usually have to do some surface treatment process for die casting parts; to achieve more advantages of die casting. the die casting post processes include deburring; sandblasting; anodizing; powder coating; CNC machining; electroplating; electrophoresis; Painting and Printing etc.
Unlike machined aluminum alloys (commonly 6061); die-cast aluminum parts normally have an uneven surface, more impurities, and no mirror effect. The most common difference between die-cast aluminum and common aluminum alloy is the poor oxidation effect of die-cast parts.
Die-casting parts need to do surface cleaning first
Surface cleaning function: remove oxidation, oil, dirt, increase adhesion, improve the appearance.
Surface cleaning methods: manual scraping, grinding wheel grinding, solution immersion to remove oil, shot blasting (not commonly used), sandblasting, polishing; water washing;
Sandblasting. Form a nibbling or pockmarked surface effect;
Polishing; to bring mirror effect (the actual polished surface flatness is still very poor).
Die Casting surface treatment
Surface treatment methods commonly used are: spray paint, spray plastic, baking paint, oxidation (not recommended), electroplating, electrophoresis, chemical solution plating
Oxidation. The raw material contains silicon, if directly anodized, the surface layer will precipitate a layer of gray-black powder, the ordinary oxidation process can not solve the problem. After polishing; sandblasting cleaning and then oxidation treatment can reduce the problem; but the actual oxidation effect is generally not ideal. Personally, it is not recommended to do anodic oxidation on the surface of die casting. If oxidation, it is recommended to use black anodic oxidation.
Electrophoresis. Need to use special paint.
Chemical solution plating. After immersion, a plating layer is formed on the surface of the part by heating the chemical solution. The solution is generally heated at about 90 degrees; which is not enough to cause cracking of the casting.
Spray paint. Because the surface adhesion of aluminum parts is not high; they cannot be directly sprayed with paint. Need to spray a special primer first; and then spray the top coat; To improve surface adhesion; you can phosphate and then spray paint operation.
Baking paint. Phosphate spraying followed by baking. Generally requires a temperature of about 200 degrees; which is not enough to cause cracking; but it is still recommended to do small batch experiments before baking the parts in large quantities.
Note: aluminum parts can also be oxidized, electrophoresis coloring.