The following are reference examples of typical metal surface treatments. As a product designer, it is necessary to understand the limitations of different processes, so I will first mention the following important points. 
The surface treatment of aluminum alloy is usually anodizing, which is not suitable for electroplating. 
The general surface treatment for zinc alloy die-cast parts is electroplating, which is not suitable for anodizing. 
The anodizing effect of aluminum alloy die-cast parts is also not good. People with high requirements for appearance should use them with caution. 
Usually, for surface treatment of metal alloys, electroplating or anodizing are chosen. What are the differences between these two processes? 
One, the handling methods are different. 
Electroplating involves the material to be plated as the cathode, while the electroplating metal or other metallic materials serve as the anode (there are also insoluble anodes). The electrolyte is a solution containing the electroplating metal ions. A certain current is input between the positive and negative electrodes. The electroplated material and the material to be plated are two different materials. For example, in the case of nickel plating on beryllium copper, beryllium copper is the base material and nickel is the electroplating material. 
Anodization is a process that uses chemical or electrochemical treatment to form a film layer containing the metal component on the metal surface. The material to be treated is protected by applying an anode and passing an electric current through a specific electrolyte to make the surface form a film layer. For example, the oxidation of aluminum alloys forms an aluminum oxide layer on the surface of the aluminum alloy. The aluminum oxide is chemically stable and will not oxidize or corrode acid, and can be dyed in various colors. 
Two: Other Processing Objects 
The objects treated by electroplating methods are mainly metals or non-metals. The commonly used electroplated metals include nickel, chromium, tin, copper, silver, gold, etc. These are the common types of electroplating such as nickel plating, chromium plating, etc. 
Anodic oxidation treatment is a method for surface treatment of metals. Most metal materials, such as stainless steel, zinc alloy, aluminum alloy, magnesium alloy, copper alloy, titanium alloy, etc., can undergo anodic oxidation in appropriate electrolytes. 
Third, the processing principles are different. 
Electroplating uses the electroplating material as the cathode, and the anodized treated material as the anode. 
Due to the effect of electric charge in electroplating, the metal anode ions move towards the cathode, obtaining electrons from the cathode and depositing on the material to be electroplated. At the same time, the metal at the anode dissolves and continuously replenishes the metal ions of the electrolyte. 
First of all, the plating solution consists of six components: main salts, additional salts, complexing agents, buffers, anode activators, and additives. 
The principles of electroplating involve four aspects: electroplating solution, electroplating reaction, electrodes and reaction principles, and the electro-deposition process of metals. 
Anodizing is the characteristic of aluminum alloys that they tend to oxidize. It uses electrochemical methods to control the formation of the oxide layer, preventing further oxidation of the aluminum and enhancing the mechanical properties of the surface. 
Generally, the anode is made of aluminum or aluminum alloy, and the cathode is a lead plate. Both the aluminum and the lead plate are placed in an aqueous solution containing substances such as sulfuric acid, oxalic acid, and chromic acid. After electrolysis, an oxide film forms on the surfaces of the aluminum and the lead plate. The wider part of this mountain is subjected to anodic oxidation using sulfuric acid. 
Aluminum alloy anodizing technology is currently widely used. Anodizing of aluminum alloy can significantly improve indicators such as surface hardness and wear resistance. The thin oxide film layer has a large number of micropores, which can adsorb various lubricants and is suitable for manufacturing engine cylinders or other wear-resistant components. The membrane's micropore adsorption capacity is strong, and it can be colored with various beautiful and ornate colors. Aluminum, magnesium, and their alloys (such as aluminum alloys) can all undergo anodizing treatment. This method is widely used in mechanical parts, aircraft and automobile parts, precision instruments and radio equipment, daily necessities, architectural decoration, etc.