Common Surface Treatment Processes for Several Materials

Vacuum plating, electrolytic polishing, pad printing process, galvanizing process, electroplating process, water transfer printing, screen printing, anodized metal brushing, in-mold decoration, etc.

1. Vacuum Plating

Vacuum plating is a physical deposition phenomenon. Argon gas is injected under vacuum, argon collides with the target material, and the target material separates into molecules that are adsorbed by the conductive product to form a uniform and smooth metal-like surface layer.

Applicable Materials: (1) Many materials can undergo vacuum plating, including metals, hard and soft plastics, composites, ceramics, and glass. The most common material for plating surface treatment is aluminum, followed by silver and copper. (2) Natural materials are not suitable for vacuum plating because their moisture content affects the vacuum environment.

Process Cost: During vacuum plating, the workpiece needs spraying, loading, unloading, and re-spraying, so labor costs are quite high, but it also depends on the complexity and quantity of the workpieces.

Environmental Impact: Vacuum plating causes very little environmental pollution, similar to the environmental impact of spraying.

2. Electrolytic Polishing

Electropolishing is an electrochemical process where atoms of the workpiece immersed in an electrolyte convert into ions and are removed from the surface due to the current, thereby removing fine burrs and increasing surface brightness.

Applicable Materials: (1) Most metals can be electropolished, with stainless steel being the most common, especially austenitic nuclear-grade stainless steel. (2) Different materials cannot be electropolished simultaneously, nor can they be placed in the same electrolyte solution.

Process Cost: The entire electropolishing process is mostly automated, so labor costs are very low.

Environmental Impact: Electropolishing uses less harmful chemicals, requires a small amount of water, and is simple to operate. Additionally, it can extend the properties of stainless steel, helping to delay corrosion.

3. Pad Printing Process

It can print text, graphics, and images on irregularly shaped object surfaces and is becoming an important special printing method.

Applicable Materials: Almost all materials can use the pad printing process, 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 significant environmental impact.

4. Galvanizing Process

A surface treatment technology that coats a layer of zinc on steel alloy materials for aesthetics and rust prevention. The zinc layer is an electrochemical protective layer that prevents metal corrosion, mainly using hot-dip galvanizing and electro-galvanizing methods.

Applicable Materials:

Since galvanizing 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 largely depends on manual surface treatment before galvanizing.

Environmental Impact: Galvanizing extends the service life of steel parts by 40-100 years, effectively preventing rust and corrosion, thus positively protecting the environment. Additionally, galvanized parts can be returned to the galvanizing bath after their service life, and the liquid zinc can be reused repeatedly without producing chemical or physical waste.

5. Electroplating Process

A process that uses electrolysis to deposit a metal film on the surface of parts, preventing metal oxidation and improving wear resistance, conductivity, reflectivity, corrosion resistance, and aesthetics. Many coins also have electroplated outer layers.

Applicable Materials: (1) Most metals can be electroplated, but different metals have different purity levels and plating efficiencies. The most common are tin, chromium, nickel, silver, gold, and rhodium. (2) The most commonly electroplated plastic is ABS. (3) Nickel metal cannot be used for electroplating products that contact skin because nickel is irritating and toxic to the skin.

Process Cost: No mold cost, but fixtures are needed to fix parts/time cost depends on temperature and metal type/labor cost (medium to high) depends on the specific electroplated parts. For example, electroplating silverware and jewelry requires highly skilled workers due to high appearance and durability requirements.

Environmental Impact: A large amount of toxic substances are used in electroplating, so professional diversion and extraction are needed to ensure minimal environmental impact.

6. Water Transfer Printing

A method that uses water pressure to print colorful patterns from transfer paper onto the surface of three-dimensional products. With increasing demands for product packaging and surface decoration, water transfer printing is becoming more widely used.

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: No mold cost, but fixtures are needed to perform water transfer printing on multiple products simultaneously. The time cost per cycle generally does not exceed 10 minutes.

Environmental Impact: Compared to product spraying, water transfer printing makes fuller use of printing coatings, reducing waste leakage and material waste.

7. Screen Printing

Ink is transferred to the substrate through mesh openings by the pressure of a squeegee, forming text and images identical to the original. Screen printing equipment is simple, easy to operate, with simple and low-cost printing and plate-making, and strong adaptability. Common printed products include color oil paintings, posters, business cards, book covers, product labels, and printed textiles.

Applicable Materials: Almost all materials can be screen printed, including paper, plastic, metal, ceramics, and glass.

Process Cost: Mold costs are low but still depend on the number of colors, as each color requires a separate plate. Labor costs are relatively high, especially when multi-color printing is involved.

Environmental Impact: Light-colored screen printing inks have less environmental impact; however, inks containing PVC and formaldehyde have harmful chemicals and must be recycled and treated promptly to prevent water pollution.

8. Anodizing

Mainly aluminum anodizing, which uses electrochemical principles to form an Al2O3 (aluminum oxide) film on the surface of aluminum and aluminum alloys. This oxide film has protective, decorative, insulating, and wear-resistant special properties.

Applicable Materials: Aluminum, aluminum alloys, and other aluminum products

Process Cost: During production, water and electricity consumption are quite high, especially in the oxidation process. The machine's own heat consumption requires continuous cooling with circulating water, with electricity consumption often around 1000 kWh per ton.

Environmental Impact: Anodizing is not outstanding in energy efficiency, and during aluminum electrolysis production, the anode effect also produces gases that have destructive side effects on the atmospheric ozone layer.

9. Metal Brushing

It is a surface treatment method that forms linear patterns on the workpiece surface through grinding, serving a decorative effect. Depending on the brushed pattern, it can be divided into: straight brushing, random brushing, ripple, and swirl.

Applicable Materials: Almost all metal materials can use the metal brushing process.

Process Cost: The process is simple, equipment is simple, material consumption is minimal, costs are relatively low, and economic benefits are high.

Environmental Impact: Pure metal products with surfaces free of paint and any chemical substances, do not burn at 600 degrees Celsius, do not produce toxic gases, and meet composite fire protection and environmental requirements.

10. In-Mold Decoration

It is a molding method where a printed film is placed inside a metal mold, and molding resin is injected into the metal mold to bond with the film, forming an integrated and cured product with the printed pattern.

Applicable Materials: Plastic surface

Process Cost: Only one set of molds is needed, reducing costs and labor time with highly automated production. The process is simplified, achieving molding and decoration simultaneously in one injection molding step.

Environmental Impact: This technology is green and environmentally friendly, avoiding pollution caused by traditional spray painting and electroplating.

The above are commonly used surface treatment processes for materials. These processes can meet different functional requirements such as corrosion resistance, wear resistance, decoration, or other special functional demands.

Disclaimer: This article is only for the exchange and sharing of composite material professional knowledge and market information, not for any commercial purposes. If there are doubts about the copyright or accuracy of the content, please contact us immediately. We will handle it promptly.