Surface treatment is a process of artificially forming a surface layer on the surface of substrate material that is different from mechanical, physical and chemical properties of substrate.
Purpose of surface treatment is to meet product's corrosion resistance, wear resistance, decoration or other special functional requirements. Our more commonly used surface treatment methods are mechanical polishing, chemical treatment, surface heat treatment, and spray surface. Surface treatment is to clean, sweep, deburr, degrease, and deoxidize surface of workpiece. Today we will learn about surface treatment process.
Common surface treatment processes are:
Vacuum plating, electroplating process, anodic oxidation, electrolytic polishing, pad printing process, galvanizing process, powder spraying, water transfer printing, screen printing, electrophoresis, etc.

Vacuum metalizing is a physical deposition phenomenon. That is, argon is injected in a vacuum state, argon hits target, separated molecules of target are absorbed by conductive goods to form a uniform and smooth metal-like surface layer.
Applicable materials:
1. Many materials can be vacuum electroplated, including metals, soft and hard plastics, composite materials, ceramics and glass. Among them, the most common surface treatment for electroplating is aluminum, followed by silver and copper.
2. Natural materials are not suitable for vacuum plating, because moisture of natural materials will affect vacuum environment.
Process cost: In vacuum plating process, workpiece needs to be sprayed, loaded, unloaded and re-sprayed, so labor cost is quite high, but it also depends on complexity and quantity of workpiece.
Environmental impact: Vacuum plating has very little environmental pollution, similar to environmental impact of spraying.

 

Electropolishing is an electrochemical process in which atoms of workpiece immersed in electrolyte are converted into ions and removed from surface due to passage of current, so as to achieve effect of removing fine burrs on the surface of workpiece and increasing brightness.
Applicable materials:
1. Most metals can be electrolytically polished, of which the 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 put in same electrolytic solvent.
Process cost: The whole process of electrolytic polishing is basically completed by automation, so labor cost is very low. Environmental impact: Electrolytic polishing uses less harmful chemicals. Entire process requires a small amount of water and is easy to operate. In addition, it can extend properties of stainless steel and delay corrosion of stainless steel.

 

Ability to print text, graphics and images on the surface of irregular and heterogeneous objects is now becoming an important special printing.
Applicable materials:
Almost all materials can be used for 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 environment.

 

Surface treatment technology of plating a layer of zinc on the surface of steel alloy materials to play role of beauty and rust prevention. Zinc layer on the surface is an electrochemical protective layer to prevent metal corrosion. Main methods used are hot-dip galvanizing and Electro-galvanized.
Applicable materials:
As 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 surface quality of workpiece depends largely on manual surface treatment before galvanizing.
Environmental impact: As galvanizing process increases service life of steel parts by 40-100 years, prevents rust and corrosion of parts, it has a positive effect on protecting environment. In addition, zinc-plated workpiece can be returned to galvanizing tank after service life expires, and repeated use of liquid zinc will not produce chemical or physical waste.

 

Process of attaching a layer of metal film to surface of parts by electrolysis, thereby preventing metal oxidation, improving wear resistance, electrical conductivity, light reflection, corrosion resistance and enhancing aesthetics. 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 electroplating efficiency. The most common ones are: tin, chromium, nickel, silver, gold and rhodium.
2. The most commonly used plastic for electroplating is ABS.
3. Nickel metal should not be used for electroplating products that contact skin, because nickel is irritating and toxic to skin.
Process cost: No mold costs, but fixtures are needed to fix parts/time cost depends on temperature and metal type/labor cost (medium-high), depending on type of specific electroplated parts. For example, electroplating of silverware and jewelry requires extremely skilled workers to operate, because of its high requirements for appearance and durability.
Environmental impact: A large number of toxic substances will be used in electroplating process, so professional diversion and extraction are required to ensure the smallest environmental impact.

 

It is a way to use water pressure to print color patterns on transfer paper on the surface of three-dimensional product. As people's requirements for product packaging and surface decoration increase, water transfer printing has become more and more widely used.
Applicable materials:
All hard materials are suitable for water transfer, and materials suitable for spraying must also be suitable for water transfer. The most common are injection molded parts and metal parts.
Process cost: There is no mold cost, but it is necessary to use a fixture to transfer multiple products at the same time. Time cost generally does not exceed 10 minutes per cycle.
Environmental impact: Compared with product spraying, water transfer printing more fully applies printing coatings, reducing possibility of waste leakage and material waste.

 

Through squeeze of squeegee, ink is transferred to substrate through mesh of graphic part to form same graphic as original. Screen printing equipment is simple, easy to operate, easy to print and plate making, low cost, and strong adaptability.
Common printed materials include: color oil paintings, posters, business cards, bound covers, commodity signs, printed and dyed textiles.
Applicable materials:
Almost all materials can be screen printed, including paper, plastic, metal, pottery and glass.
Process cost: Mold cost is low, but it still depends on number of colors, because each color has to be made separately. Labor cost is high, especially when it comes to multi-color printing.
Environmental impact: Light-colored screen printing inks have little impact on environment, but inks containing PVC and formaldehyde have harmful chemical substances, need to be recycled and treated in time to prevent water pollution.

 

It is mainly anodization of aluminum, which uses electrochemical principles to form a layer of Al2O3 (aluminum oxide) film on the surface of aluminum and aluminum alloy. This 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 production process, consumption of water and electricity is quite large, especially in oxidation process. Heat consumption of machine itself needs to be continuously cooled with circulating water, and electricity consumption per ton is often around 1000 degrees.
Environmental impact: Anodizing is not excellent in terms of energy efficiency. At the same time, in production of aluminum electrolysis, anode effect can also produce gases that cause destructive side effects on atmospheric ozone layer.

 

It is a surface treatment method that forms lines on the surface of workpiece by grinding products to achieve a decorative effect. According to different lines after drawing, it can be divided into: straight line drawing, random line drawing, corrugation, and swirling.
Applicable materials: Almost all metal materials can use metal wire drawing process.
Process cost: Process method is simple, equipment is simple, material consumption is low, cost is relatively low, and economic benefit is high.
Environmental impact: pure metal products, no paint and any chemical substances on the surface, 600 degrees high temperature does not burn, no toxic gas, meet requirements of fire protection and environmental protection.

 

It is a molding method in which film with printed pattern is put into a metal mold, resin for molding is injected into metal mold to join film, so that printed film and resin are integrated, cured 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 for highly automated production. Process is simplified. There is a one-time injection molding method to achieve both molding and decoration.
Environmental impact: Technology is green and environmentally friendly, avoiding pollution caused by traditional spray paint and electroplating.