Surface treatment is a process method that artificially forms a surface layer on the surface of the base material with different mechanical, physical and chemical properties from the base material.
The purpose of surface treatment is to meet the corrosion resistance, wear resistance, decoration or other special functional requirements of the product. The surface treatment methods we commonly
use are mechanical grinding, chemical treatment, surface heat treatment, and surface spraying. Surface treatment is to clean, sweep, deburr, degrease, and deoxidize the surface of the workpiece.
Common surface treatment processes include:
Vacuum plating, electroplating process, anodizing, electrolytic polishing, pad printing process, galvanizing process, powder spraying, water transfer printing, screen printing, electrophoresis, etc.
1、Vacuum Metalizing
Vacuum Metalizing is a physical deposition phenomenon. That is, argon is injected under vacuum, and the argon hits the target material, and the target material is separated into molecules that are adsorbed by the conductive material to form a uniform and smooth metal-like surface layer.
Applicable materials:
Many materials can be vacuum plated, including metals, soft and hard plastics, composite materials, ceramics and glass. Among them, aluminum is the most commonly used for electroplating surface treatment, followed by silver and copper.
Natural materials are not suitable for vacuum plating because the moisture in the natural materials themselves will affect the vacuum environment.
Process cost: During the vacuum plating process, the workpiece needs to be sprayed, loaded, unloaded and sprayed again, so the labor cost is quite high, but it also depends on the complexity and quantity of the workpiece.
Environmental impact: Vacuum Metalizing has little environmental pollution, similar to the impact of spraying on the environment.
2、Electropolishing
Electropolishing is an electrochemical process in which the atoms of the workpiece immersed in the electrolyte are converted into ions and removed from the surface due to the passage of electric current, thereby achieving the effect of removing fine burrs and increasing the brightness of the workpiece surface.
Applicable materials:
Most metals can be electropolished, and the most common use is for surface polishing of stainless steel (especially austenitic nuclear grade stainless steel).
Different materials cannot be electropolished at the same time, and cannot even be placed in the same electrolytic solvent.
Process cost: The entire process of electropolishing is basically completed by automation, so the labor cost is very low. Environmental impact: Electropolishing uses less harmful chemicals, the entire process requires a small amount of water and is simple to operate. In addition, it can prolong the properties of stainless steel and play a role in delaying corrosion of stainless steel.
3、Pad Printing
The ability to print text, graphics and images on irregular surfaces is now becoming an important specialty printing.
Applicable materials:
Almost all materials can be printed using pad printing, except for materials that are softer than silicone pads, such as PTFE.
Process cost: Low mold cost and low labor cost.
Environmental impact: Since this process is limited to soluble inks (which contain harmful chemicals), it has a great impact on the environment.
4、Galvanizing
A surface treatment technology that coats the surface of steel alloy materials with a layer of zinc for aesthetics and rust prevention. The surface zinc layer is an electrochemical protective layer that can prevent metal corrosion. The main methods used are hot-dip galvanizing and electro-galvanizing.
Applicable materials:
Since the galvanizing process relies on metallurgical bonding technology, it is only suitable for surface treatment of steel and iron.
Process cost: No mold cost, short cycle/medium labor cost, because the surface quality of the workpiece depends largely on the manual surface treatment before galvanizing.
Environmental impact: Since the galvanizing process increases the service life of steel parts by 40-100 years and prevents rust and corrosion of the workpiece, it has a positive effect on protecting the environment. In addition, the galvanized workpiece can be returned to the galvanizing tank after the service life expires, and the repeated use of liquid zinc will not produce chemical or physical waste.
5、Electroplating
The process of using electrolysis to attach a layer of metal film to the surface of parts, thereby preventing metal oxidation, improving wear resistance, conductivity, reflectivity, corrosion resistance and enhancing beauty. The outer layer of many coins is also electroplated.
Applicable materials:
Most metals can be electroplated, but different metals have different levels of purity and electroplating efficiency. The most common ones are: tin, chromium, nickel, silver, gold and rhodium.
The most commonly used plastic for electroplating is ABS.
Nickel metal cannot be used for electroplating products that contact the skin because nickel is irritating and toxic to the skin.
Process cost: No mold cost, but a fixture is required to fix the parts/time cost depends on temperature and metal type/manpower cost (medium-high), depending on the specific type of electroplated parts, such as silverware and jewelry electroplating requires extremely skilled workers to operate because it has high requirements for appearance and durability.
Environmental impact: A large amount of toxic substances will be used in the electroplating process, so professional diversion and extraction are required to ensure minimal environmental impact.
6、Hydro Transfer Printing
It is a way to use water pressure to print the colored pattern on the transfer paper on the surface of a three-dimensional product. As people's requirements for product packaging and surface decoration increase, the use of water transfer printing is becoming more and more extensive.
Applicable materials:
All hard materials are suitable for water transfer printing, and materials suitable for spraying are also suitable for water transfer printing. The most common are injection molded parts and metal parts.
Process cost: There is no mold cost, but a fixture is required to transfer multiple products at the same time, and the time cost is generally no more than 10 minutes per cycle.
Environmental impact: Compared with product spraying, water transfer printing makes more full use of printing coatings, reducing the possibility of waste leakage and material waste.
7、Screen Printing
Through the extrusion of the scraper, the ink is transferred to the substrate through the mesh of the image part, forming the same image as the original. Screen printing equipment is simple, easy to operate, simple and low-cost for printing and plate making, and highly adaptable.
Common printed materials include: color oil paintings, posters, business cards, binding covers, product labels, and printed and dyed textiles.
Applicable materials:
Almost all materials can be screen printed, including paper, plastic, metal, ceramics, and glass.
Process cost: The mold cost is low, but it still depends on the number of colors, because each color must be plated separately. The labor cost is high, especially when it comes to multi-color printing.
Environmental impact: Light-colored screen printing inks have less impact on the environment, but inks containing PVC and formaldehyde have harmful chemicals and need to be recycled and treated in time to prevent water pollution.
8、Anodic Oxidation
It is mainly the anodizing of aluminum, which uses electrochemical principles to form a layer of Al2O3 (aluminum oxide) film on the surface of aluminum and aluminum alloys. This oxide film has special characteristics such as protection, decoration, insulation, and wear resistance.
Applicable materials:
Aluminum products such as aluminum and aluminum alloys
Process cost: 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 needs to be continuously cooled by circulating water, and the power consumption per ton is often around 1000 degrees.
Environmental impact: Anodizing is not outstanding in terms of energy efficiency. At the same time, in the production of aluminum electrolysis, the anode effect will also produce gases that have destructive side effects on the atmospheric ozone layer.
9、Metal Wired
It is a surface treatment method that forms lines on the surface of the workpiece by grinding the product to achieve a decorative effect. According to the different lines after drawing, it can be divided into: straight drawing, random drawing, corrugation, and spiral drawing.
Applicable materials: Almost all metal materials can use the metal drawing process.
Process cost: The process method is simple, the equipment is simple, the material consumption is very small, the cost is relatively low, and the economic benefit is high.
Environmental impact: Pure metal products, no paint or any chemical substances on the surface, no combustion at 600 degrees high temperature, no toxic gas, and meet the requirements of fire protection and environmental protection.
10、In-Mold Decoration-IMD
It is a molding method that puts the printed pattern film into a metal mold, injects the molding resin into the metal mold and joins it with the film, so that the printed pattern film and the resin form a whole and solidify into a finished product.
Applicable materials: plastic surface
Process cost: Only one set of molds is needed, which can reduce costs and working hours. Highly automated production, simplified process, one-time injection molding method, and molding and decoration are achieved at the same time.
Environmental impact: This technology is green and environmentally friendly, avoiding the pollution caused by traditional spray painting and electroplating.