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.
The purpose of surface treatment 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, and surface spraying. Surface treatment is to clean, sweep, deburr, degrease, and descale the surface of the workpiece. Today we will learn about the surface treatment process.
The commonly used surface treatment processes are:
Vacuum electroplating, electroplating process, anodizing, electrolytic polishing, pad printing process, galvanizing process, powder coating, water transfer printing, screen printing, electrophoresis, etc.
01. Vacuum plating
—— Vacuum Metalizing ——
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.
Applicable materials:
1. Many materials can be vacuum plated, including metals, soft and hard plastics, composite materials, ceramics and glass. The most common surface treatment for electroplating is aluminum, followed by silver and copper.
2. Natural materials are not suitable for vacuum plating, because the moisture of natural materials will affect the vacuum environment.
Process cost: In the process of vacuum plating, 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.
Environmental impact: Vacuum electroplating has little environmental pollution, similar to the impact of spraying on the environment.
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02. Electropolishing
—— 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 workpiece surface.
Applicable materials:
1. Most metals can be electrolytically polished, and it is most commonly used for surface polishing of stainless steel (especially for austenitic nuclear grade stainless steel).
2. Different materials cannot be electropolished at the same time, or even placed in the same electrolytic solvent.
Process cost: The whole process of electrolytic polishing is basically completed automatically, so the labor cost is very low. Environmental impact: Electrolytic polishing uses less harmful chemicals. The whole process requires a small amount of water and is easy to operate. In addition, it can prolong the properties of stainless steel and delay corrosion of stainless steel.
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03. Pad printing process
——Pad Printing——
Being able to print text, graphics and images on the surface of irregular shaped objects is now becoming an important special printing.
Applicable materials:
Pad printing can be used for almost all materials, except materials 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 high environmental impact.
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04. Galvanizing process
—— Galvanizing ——
A surface treatment technology that coats a layer of zinc on the surface of steel alloy materials for aesthetics and anti-rust effects. The zinc layer on the surface is an electrochemical protective layer that can prevent metal corrosion. The main methods used are hot-dip galvanizing and Galvanized.
Applicable materials:
Since the galvanizing process relies on metallurgical bonding technology, it is only suitable for the surface treatment of steel and iron.
Process cost: no mold cost, short cycle/medium labor cost, because the surface quality of the workpiece largely depends 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 the 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 its service life expires, and the repeated use of liquid zinc will not produce chemical or physical waste.
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05. Electroplating process
—— Electroplating ——
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 enhance aesthetics. The outer layer of many coins is also electroplated. .
Applicable materials:
1. Most metals can be electroplated, but different metals have different levels of purity and plating efficiency. The most common of these are: tin, chromium, nickel, silver, gold and rhodium.
2. The most commonly used plastic for electroplating is ABS.
3. Nickel metal cannot be used for electroplating products that touch the skin, because nickel is irritating and toxic to the skin.
Process cost: no mold cost, but fixtures are required to fix the parts / time cost depends on temperature and metal type / labor cost (medium-high), depends on the type of specific plating parts, such as silverware and jewelry plating requires extremely It is operated by highly skilled workers because of its high requirements on appearance and durability.
Environmental impact: A large number of toxic substances are used in the electroplating process, so professional diversion and extraction are required to ensure minimal environmental impact.
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06. Water transfer printing
—— Hydro Transfer Printing ——
It is a way to print the color pattern on the transfer paper on the surface of the three-dimensional product by using water pressure. With the improvement of people's requirements for product packaging and surface decoration, 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 must also be suitable for water transfer printing. The most common are injection molded parts and metal parts.
Process cost: There is no mold cost, but multiple products need to be water-transferred at the same time using fixtures, and the time cost generally does not exceed 10 minutes per cycle.
Environmental impact: Compared with product spraying, water transfer printing more fully applies printing paint, reducing the possibility of waste leakage and material waste.
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07. Screen printing
—— Screen Printing ——
Through the extrusion of the scraper, the ink is transferred to the substrate through the mesh of the graphic part, forming the same graphic as the original. Screen printing equipment is simple, easy to operate, easy to print and plate-making, with low cost and strong adaptability.
Common printed materials include: color oil paintings, posters, business cards, bound covers, commodity signs, and printed and dyed textiles.
Applicable materials:
Almost any material 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 needs to be plate-made separately. Labor costs are high, especially when it comes to multi-color printing.
Environmental impact: Light-colored screen printing inks have little impact on the environment, but inks containing PVC and formaldehyde contain harmful chemical substances, which need to be recycled and disposed of in time to prevent water pollution.
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08. Anodizing
—— Anodic Oxidation ——
The anodic oxidation of aluminum is mainly based on the electrochemical principle to form a layer of Al2O3 (aluminum oxide) film on the surface of aluminum and aluminum alloy. This layer of oxide film has special characteristics such as protection, decoration, insulation, and wear resistance.
Applicable materials:
Aluminum, aluminum alloy and other aluminum products
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, while in the production of aluminum electrolysis, the anode effect also produces gases that have damaging side effects on the atmospheric ozone layer.
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09. Metal wire drawing
—— 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 textures after wire drawing, it can be divided into: straight wire drawing, chaotic wire drawing, corrugated, and swirling.
Applicable materials: Almost all metal materials can use metal wire drawing process.
Process cost: The process method is simple, the equipment is simple, the material consumption is very little, 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, 600 degrees high temperature does not burn, does not produce toxic gases, meets fire protection and environmental protection requirements.
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10. In-mold decoration
—— In-Mold Decoration-IMD ——
It is a molding method that puts the pattern-printed diaphragm into the metal mold, injects the resin for molding into the metal mold and joins the diaphragm, and makes the pattern-printed diaphragm and the resin integrated and solidified into a finished product.
Applicable material: plastic surface
Process cost: only need to open a set of molds, which can reduce costs and man-hours, high-automatic production, simplified manufacturing process, one-time injection molding method, and achieve molding and decoration at the same time.
Environmental impact: This technology is green and environmentally friendly, avoiding the pollution caused by traditional painting and electroplating.
