Surface treatment is a process that artificially forms a layer on the surface of a base material that has different mechanical, physical and chemical properties from base material.
Purpose of surface treatment is to meet corrosion resistance, wear resistance, decoration or other special functional requirements of 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, remove oil, and remove scale on the surface of workpiece. Today we will learn about surface treatment process.
Commonly used surface treatment processes include:
Vacuum electroplating, electroplating process, anodizing, electrolytic polishing, pad printing process, galvanizing process, powder spraying, water transfer printing, screen printing, electrophoresis, etc.

Vacuum plating is a physical deposition phenomenon. That is, argon gas is injected under a vacuum state, and argon gas hits target material. Target material is separated into molecules and are adsorbed by conductive goods to form a uniform and smooth imitation metal surface layer.
Applicable materials:
1. Many materials can be vacuum electroplated, 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.
2. Natural materials are not suitable for vacuum plating because moisture in natural materials themselves will affect vacuum environment.
Process cost: During vacuum electroplating 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 electroplating has very little environmental pollution, similar to impact of spraying on environment.

 

Electropolishing is an electrochemical process in which atoms of a workpiece immersed in an electrolyte are converted into ions and removed from surface due to passage of current, thereby achieving effect of removing fine burrs and increasing brightness on the surface of workpiece.
Applicable materials:
1. Most metals can be electrolytically polished, which is most commonly used for surface polishing of stainless steel (especially suitable for austenitic nuclear grade stainless steel).
2. Different materials cannot be electrolytic polished at the same time, or even placed in same electrolytic solvent.
Process cost: The entire process of electrolytic polishing is basically completed automatically, so labor costs are very low. Environmental impact: Electrolytic polishing uses less harmful chemicals. The entire process requires a small amount of water and is simple to operate. In addition, it can extend properties of stainless steel and delay corrosion of stainless steel.

 

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 on almost all materials, except for 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 significant impact on environment.

 

Surface treatment technology that coats surface of steel alloy materials with a layer of zinc for aesthetics, rust prevention, etc. Zinc layer on the surface is an electrochemical protective layer that can prevent metal corrosion. Main methods used are hot-dip galvanizing and Electro-galvanized.
Applicable materials:
Since galvanizing process relies on metallurgical bonding technology, it is only suitable for surface treatment of steel and iron.
Process cost: no mold fees, short cycle time/medium labor cost, because surface quality of workpiece largely depends on manual surface treatment before galvanizing.
Environmental impact: Since galvanizing process increases service life of steel parts by 40-100 years, prevents rust and corrosion of workpieces, it plays a positive role in protecting environment. In addition, galvanized workpieces can be returned to galvanizing tank after their service life expires, and repeated use of liquid zinc will not produce chemical or physical waste.

 

A process that uses electrolysis to attach a metal film to surface of parts, thereby preventing metal oxidation, improving wear resistance, conductivity, reflectivity, corrosion resistance, and improving aesthetics. Outer layers of many coins are 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. Plastic most commonly used for electroplating is ABS.
3. Nickel metal cannot be used for plating products that come into contact with skin because nickel is irritating and toxic to skin.
Process cost: No mold fee, but fixtures are needed to fix parts/Time cost depends on temperature and metal type/Labor cost (medium-high), depends on type of specific electroplated parts. For example, electroplating of silverware and jewelry requires extremely skilled workers because of its high requirements on appearance and durability.
Environmental impact: A large number of toxic substances are used in electroplating process, so professional diversion and extraction are required to ensure minimal environmental impact.

 

It is a method of printing color patterns on transfer paper onto the surface of three-dimensional products using water pressure. As people's requirements for product packaging and surface decoration increase, water transfer printing is used more and more widely.
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 ones are injection molded parts and metal parts.
Process cost: There is no mold cost, but you need to use a fixture to water 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 squeezing of scraper, the ink is transferred to substrate through mesh of graphic part, forming same graphic and text as original. Screen printing equipment is simple, easy to operate, easy to print and plate making, low in cost, and has strong adaptability.
Common printed materials include: color oil paintings, posters, business cards, binding covers, product signs, printed and dyed textiles, etc.
Applicable materials:
Almost any material can be screen printed, including paper, plastic, metal, ceramics and glass.
Process cost: Mold cost is low, but it still depends on number of colors, because each color needs to be plated separately. Labor costs are on high side, especially when it comes to multi-color printing.
Environmental impact: Light-colored screen printing inks have less impact on environment. However, inks containing PVC, formaldehyde contain harmful chemicals and need to be recycled and processed in time to prevent contamination of water resources.

 

Mainly anodizing aluminum, which uses electrochemical principles to generate an Al2O3 (aluminum oxide) film on the surface of aluminum and aluminum alloys. This oxide film has special properties such as protection, decoration, insulation, and wear resistance.
Applicable materials:
Aluminum, aluminum alloy and other aluminum products
Process cost: During production process, consumption of water and electricity is considerable, especially in oxidation process. Heat consumption of machine itself requires constant use of circulating water for cooling, and power consumption per ton is often around 1,000 degrees.
Environmental impact: Anodization is not excellent in terms of energy efficiency. At the same time, in production of aluminum electrolysis, anode effect also produces gases that have damaging side effects on atmospheric ozone layer.

 

It is a surface treatment method that uses grinding products to form lines on the surface of workpiece to achieve a decorative effect. According to different textures after drawing, it can be divided into: straight grain drawing, random grain drawing, corrugated grain, and spiral grain.
Applicable materials: Almost all metal materials can use metal drawing process.
Process cost: Process method is simple, equipment is simple, material consumption is very small, cost is relatively low, and economic benefits are high.
Environmental impact: pure metal products, no paint or any chemical substances on the surface, does not burn at 600 degrees high temperature, does not produce toxic gases, complies with fire protection and environmental protection requirements.

 

It is a molding method in which a diaphragm with a printed pattern is placed into a metal mold, and molding resin is injected into metal mold to join diaphragm, so that diaphragm with printed pattern and resin are integrated and solidified into a finished product.
Applicable materials: plastic surface
Process cost: Only one set of molds is needed, which can reduce costs and man-hours for highly automated production. Process is simplified. There is a one-shot injection molding method that achieves molding and decoration at the same time.
Environmental impact: This technology is green and environmentally friendly, avoiding pollution caused by traditional spray painting and electroplating.