Surface treatment is a method of artificially forming a surface layer on the surface of a base material with mechanical, physical and chemical properties different from that of the base. To put it simply, it is to clean, sweep, deburr, degrease, descale, etc. the surface of the workpiece, the purpose of which is to meet the corrosion resistance, wear resistance, decoration or other special functional requirements of the product. Our more commonly used surface treatment methods are: mechanical grinding, chemical treatment, surface heat treatment, surface spraying. There are ten commonly used surface treatment processes:
Vacuum electroplating, electrolytic polishing, anodizing, electroplating process, pad printing process, galvanizing process, metal wire drawing, water transfer printing, screen printing,In-mold decoration, etc. Today, let’s introduce the first five processes:
1. Vacuum plating
Vacuum plating is a physical deposition phenomenon. That is, argon gas is injected in a vacuum state, and the argon gas hits the target material, and the target material is separated into molecules that are adsorbed by conductive goods to form a uniform and smooth imitation metal surface layer.
Its applicable materials include metals, soft and hard plastics, composite materials, ceramics and glass. The most common surface treatment for electroplating is aluminum, followed by silver and copper. During the vacuum plating process, the workpiece needs to be sprayed, loaded, unloaded and re-sprayed, so the labor cost is quite high, but it also depends on the complexity and quantity of the workpiece. But the environmental pollution is very small, similar to the impact of spraying on the environment.
2. Electropolishing
Electropolishing is an electrochemical process in which atoms of a workpiece immersed in an electrolyte are converted into ions and removed from the surface due to the passage of an electric current, thereby achieving the effect of removing fine burrs and increasing the brightness of the surface of the workpiece. Most metals can be electrolytically polished, the most commonly used for surface polishing of stainless steel (especially for austenitic nuclear grade stainless steel), which can prolong the properties of stainless steel and delay corrosion of stainless steel. Different materials cannot be electropolished at the same time, or even placed in the same electrolytic solvent. The whole process is completed automatically, so the labor cost is very low.
3. Anodizing
It is mainly anodic oxidation of aluminum or aluminum alloy products, which uses electrochemical principles to form a layer of Al2O3 (aluminum oxide) film on the surface of aluminum and aluminum alloys. This layer of oxide film has special characteristics such as protection, decoration, insulation, and wear resistance. In the production process, the consumption of water and electricity is quite large, especially in the oxidation process. The heat consumption of the machine itself requires continuous cooling with circulating water. Moreover, anodization is not excellent in terms of energy efficiency. At the same time, in the production of aluminum electrolysis, the anode effect will also produce gases that cause destructive side effects on the atmospheric ozone layer, which is harmful to the environment.
4. Electroplating process
The process of attaching a layer of metal film to the surface of parts by electrolysis, so as to prevent metal oxidation, improve wear resistance, conductivity, light reflection, corrosion resistance and improve appearance. The outer layer of many coins is also electroplated. . Most metals can be plated, but different metals have different levels of purity and plating efficiency. The most common of these are: tin, chromium, nickel, silver, gold and rhodium. Nickel metal should not be used to plate products that come into contact with the skin because nickel is an irritant and toxic to the skin. A large number of toxic substances are used in the electroplating process, so professional shunting and extraction are required to ensure minimal environmental impact. The specific cost depends on the type of specific plated parts.
5. Pad printing process
Being able to print text, graphics and images on the surface of irregular shaped objects is now becoming an important special printing.
Applicable materials: almost all materials can use the pad printing process, except for materials softer than silicone pads, such as PTFE, etc. Low mold cost and low labor cost. Since the process is limited to soluble inks (which contain harmful chemicals), it has a high environmental impact.