14 Classic Surface Printing Processes

1. Vacuum Plating

Vacuum plating (c): A kind of physical deposition phenomenon. That is, under the vacuum state, argon gas is injected, and the argon gas hits the target, and the separated molecules of the target are adsorbed by the conductive goods to form a uniform and smooth imitation metal surface layer.

Typical products: Surface treatment of reflective coatings, consumer electronics and heat shields

Suitable output: Single piece to large batch

Quality: High quality ( highlights and product surface protection)

Speed: Medium production speed, 6 hours / cycle (including painting)

Applicable materials

1. Many materials can be vacuum plated, including metals, soft and hard plastics, composite materials, ceramics and glass.Among them, aluminum is most commonly used for electroplated surface treatment, 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

Vacuum plating relies on manual operations. During the vacuum plating process, the workpiece needs to be sprayed, loaded, unloaded and repainted, so the labor cost is quite high, but it also depends on the complexity and quantity of the workpiece.

Impact on the Environment

Vacuum plating has little environmental pollution, similar to the environmental impact of spraying.

Examples:

Vacuum plating for Ducati motorcycles

Vacuum plating of perfume bottles

Vacuum plating of other products

2. Electropolishing

Electropolishing: The workpiece to be polished is used as the anode, and the insoluble metal is used as the cathode. Both electrodes are immersed in the electrolytic bath at the same time, and selective anodic dissolution is generated by the direct current ionization reaction, so as to achieve the effect of removing small burrs on the surface of the workpiece and increasing the brightness.

Typical products: Building structures, food handling and storage as well as medical pharmaceuticals

Suitable output: Single piece to large batch

Quality: The surface is bright, smooth and hygienic

Speed: Medium production speed, 5-30 minutes / cycle

Applicable Materials

1. Most metals can be electropolished, most commonly be used for stainless steel surface polishing (especially for super austenitic stainless steel).
2. Different materials cannot be electrolytically polished at the same time, or even in the same electrolytic solvent.

Process Cost

The whole process of electropolishing is basically completed by automation, so the labor cost is very low.

Impact on the Environment

Electropolishing uses less harmful chemicals. The entire process requires a small amount of water and is easy to operate. In addition, it can extend the properties of stainless steel and delay the corrosion of stainless steel.

Examples

Electropolishing to clean welds

Electropolishing of other products

3. Photo Etching

Photo Etching surface treatment, abbreviated as Photo etching, a method of making a resist film image by photographic means to protect the surface, and generating surface texture by etching on a metal, plastic, etc. with a chemical etchant.

Typical products: Surface treatment for jewellery, nameplates and trophies

Suitable output: Single piece to large batch

Quality: Extend exposure and chemicals all can realize Photo Etching

Speed: Medium production speed (50-100 microns / 5 minutes)

Applicable Materials

1. Most metals are suitable for photo etching. The most common are stainless steel, mild steel, aluminum, brass, nickel, tin, copper and silver. Among them, aluminum has the fastest photo etching speed, while stainless steel has the slowest.
2. Glass and ceramic are also suitable for photo etching surface treatment, but different photoresist and chemicals are required.

Process Cost

1. Low mold cost
2. Medium labor cost

Impact on the Environment

Metal scrap generated by photo etching must be controlled for recycling. The chemical used for photoetching is also one-third of ferric chloride, and caustic soda (fire alkali) is also used to treat discarded photosensitive films. Both chemicals are harmful, so operators need to wear protective clothing when handling them.

Examples

Photo etching of eyeglass frames

Photo etching of metal signs

4. Pad Printing

Pad Printing: It can print text, graphics, and images on the surface of irregularly shaped objects and now is becoming an important special printing.

Typical products: Surface printing for vehicle interiors, consumer electronics and sports equipment

Suitable output: Single piece to large batch

Quality: Clear print details, even on uneven surfaces

Speed: Single printing time (1-5 seconds)

Applicable Materials

Almost all materials can use the pad printing process, except the materials that are softer than silicone pads, such as PTFE.

Process Cost

1. Low mold cost
2. Low labor cost, because most of the processes are completed by machining

Impact on the Environment

Because this process is limited to soluble inks (which contain harmful chemicals), so it has a great impact on the environment.

Examples

Customized Service of Pad Printing and Swiss Army Knives

Pad Printing of clothing

Pad printing of silicone mobile phone

Pad printing of other product

5. Galvanizing

Galvanizing: It is a surface treatment technology that plated a layer of zinc on the surface of steel alloy materials to play a role of beauty and rust prevention. The zinc layer on the surface is an electrochemical protection layer that can prevent metal from being damaged. The main methods used are hot-dip galvanizing and galvanizing.

Typical products: Surface treatment for buildings, bridges, vehicles, furniture and etc.

Suitable output: Single piece to large batch

Quality: Perfect protective layer, the appearance largely depends on the quality of the steel

Speed: Fast, basic 10 minutes / cycle

Applicable Materials

As the galvanizing process relies on metallurgical bonding technology, so it is only suitable for the surface treatment of steel and iron.

Process Cost

1. No mold cost, short cycle, so the cost is low
2. The labor cost is medium, because the surface quality of the workpiece largely depends on the artificial surface treatment before galvanizing.

Impact on the Environment

As the galvanizing process increases the service life of steel parts by 40-100 years, it can prevent the rust and corruption of the workpiece, so it has a positive effect on protecting the environment. In addition, the galvanized workpiece can be returned to the galvanizing tank after the end of its service life, and repeated use of liquid zinc will not produce chemical and physical waste.

Examples

Galvanizing of hubs

Galvanizing plant

Galvanizing of building firmware

Galvanizing of other product

6. Electroplating

Electroplating: A process for attaching a metal film to the surface of a part by using electrolysis. It can prevent metal oxidation, improve wear resistance, electrical conductivity, light reflectivity, corrosion resistance, and the aesthetics. The outer layer of many coins is also electroplated.

Typical products: Surface treatment for transportation, consumer electronics, furniture, jewelry and silverware, etc.

Suitable output: Single piece to large batch

Quality: Extremely high gloss, resistant to oxidation and corrosion

Speed: Medium speed, depending on material type and coating thickness

Applicable Materials

1. Most metals can be plated, but different metals have different levels of purity and plating efficiency. The most common are: tin, chromium, nickel, silver, gold and rhodium (Rhodium: A type of platinum that is extremely expensive and can maintain high brightness for a long time. It can resist most chemicals and acids. Most commonly used for products with extremely high surface gloss requirements, such as trophies and medals).
2. The plastic most commonly used for electroplating is ABS, because ABS can withstand the high temperature of electroplating at 60 ° C (140 ° F), and its bonding strength between electroplated layer and non-plated layer is high.
3. Nickel metal should not be used for electroplating products that contact the skin, because nickel is irritating and toxic to the skin.

Process Cost

1. No mold costs, but fixtures are needed to fix the parts.
2. Time cost depends on temperature and metal type.
3. Labor costs (medium-high), depending on the type of plating, such as silver and jewelry plating requires extremely skilled workers to operate, because of its high requirements on appearance and durability.

Impact on the Environment

A large amount of toxic substances will be used in the electroplating process, so professional shunting and extraction are needed to ensure minimal environmental impact.

Examples

Domestic factory live plating processing

Electroplating of spoon

Electroplating of other products

7. Powder Coating

Powder Coating is a kind of dry spray method. It’s used for spraying or fluidized bed on some metal workpieces. The powder is electrostatically adsorbed on the surface of the workpiece, and when it is completely dry, a protective film is formed on the surface.

Typical products: Coating of vehicles, buildings and white goods

Suitable output: Single piece to large batch

Quality: The surface of the product is smooth and evenly colored

Speed: The speed depends on workpiece size and degree of automation and it takes at least 30 minutes to dry.

Applicable Materials

Although powder spraying is suitable for the surface spraying of some metal parts, plastics and glass, but it is mainly used to protect or color aluminum and steel.

Process Cost

1. No mold costs, but equipment costs are very high
2. The time cost is short, but the drying time needs at least half an hour
3. Labor costs are quite low

Impact on the Environment

Compared with wet spraying, powder spraying has a higher material utilization rate (due to the electrostatic adsorption of powder particles), which can reach a spray utilization rate of 95%.

Examples

Powder coating of hubs

Live shooting of powder coating plant

Powder coating of railings

Powder coating of other products

8. Hydro Transfer Printing

Hydro transfer printing is a method of printing the color patterns on the transfer paper onto the surface of a three-dimensional product using water pressure. With the increase of people’s requirements for product packaging and surface decoration, the use of hydro transfer printing is becoming more and more widespread.

Typical products: Printing for transportation, consumer electronics and military products

Suitable output: Small batch to large batch

Quality: The surface texture of the product is precise and clear, but there is a slight stretch

Speed: Fast, around 10 to 20 cycles / hour

Applicable Materials

All hard materials are suitable for hydro transfer printing, and materials suitable for spraying must also be suitable for hydro transfer printing. The most common are injection molded and metal parts.

Process Cost

1. No mold costs, but need to use fixtures to do the hydro transfer printing to multiple products at the same time, and this will reduce the time costs.
2. The time cost is little, and generally does not exceed 10 minutes per cycle.

Impact on the Environment

Compared with product coating, hydro transfer printing application of printing paint is more fully, reducing the possibility of waste leakage and material waste.

Examples

Hydro transfer printing from an underwater perspective

Hydro transfer printing on the water gun

Hydro transfer printing of other products

9. Screen Printing

Screen Printing: Through the squeezing of the scraper, the ink is transferred to the substrate through the mesh of the graphic part to form the same graphic as the original. Screen printing equipment has the advantages of simplicity, easy operation, simple printing and plate making, low cost, and strong adaptability. Screen printing has a wide range of applications. Common prints include: color oil paintings, posters, business cards, decorative covers, commodity signs, and printed textiles.

Typical products: Used for clothing, electronics and packaging

Suitable output: Single piece to large batch

Quality: High precision of pattern details

Speed: Manual silk screen (1-5 cycles / minute), machine silk screen (1-30 cycles / minute)

Applicable Materials

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

Process Cost

1. The mold cost is low, but it still depends on the number of colors, because each color has to be plated separately.
2. Time cost: up to 30 per minute for machine screen printing, up to 1-5 per minute for manual screen printing
3. Labor cost: In manual screen printing, labor cost is high, especially when it comes to colorful printing

Impact on the Environment

Light-colored screen printing inks have less impact on the environment. However, inks containing PVC and formaldehyde have harmful chemicals and need to be recycled and disposed of in time to prevent water pollution.

Examples

Screen printing of skateboard pattern

Screen printing of clothing

Screen printing of other products

10. Anodic Oxidation

Anodic Oxidation, it is mainly anodizing of aluminum. It uses the principle of electrochemistry to form an Al2O3 (alumina) film on the surface of aluminum and aluminum alloy. This layer of oxide film has special properties such as protection, decoration, insulation and abrasion resistance.

Typical products: Mobile phones, computers and other electronic products, mechanical parts, aircraft and automobile parts, precision instruments and radio equipment, daily necessities and architectural decoration.

Suitable output: Single piece to large batch

Quality: The oxide film has special characteristics such as protection, decoration, insulation and abrasion resistance.

Speed: Tens of minutes

Applicable Materials

Aluminum products such as aluminum and aluminum alloys

Process Cost

In the production process of anodization, the consumption of water and electricity is considerable, especially in the oxidation process. Coupled with the heat consumption of the machine itself, it is necessary to keep cooling with circulating water. The power consumption per ton is often around 1000 degrees. The reduction of auxiliary facilities can reduce some power consumption.

Impact on the Environment

Anodizing does not perform well in terms of energy efficiency. At the same time, in the aluminum electrolytic production, the anode effect will also produce gases that cause destructive side effects on the atmospheric ozone layer.

Examples

Lenses made with Anodic Oxidation

Colorful metal rear case player

11. Electrophoresis Deposition – ED

ED-Electrophoresis Deposition: Under the action of an electric field, a charged particle moves toward its typical opposite electrode, which is called ED-Electrophoresis Deposition.

Typical products: Automobiles, building materials, hardware, home appliances, etc.

Suitable output: Mass production

Quality: The product presents a variety of colors and maintains metallic luster. At the same time, the surface performance is enhanced, and it has good anti-corrosion performance.

Speed: Faster production speed

Applicable Materials

Stainless steel, aluminum alloy, etc.

Process Cost

It can realize mechanization and automatic continuous operation, also has low labor costs and low total costs.

Impact on the Environment

ED-Electrophoresis Deposition coatings use water as a solvent, and are non-flammable and non-toxic. It saves a lot of organic solvents, greatly reduce air pollution and environmental hazards, and also avoid the hidden dangers of fire.

Examples

12. Micro-arc oxidation – MAO

Micro-arc oxidation, also known as micro-plasma oxidation, is a combination of electrolyte and corresponding electrical parameters. On the surface of aluminum, magnesium, titanium, and their alloys, a ceramic film mainly composed of a base metal oxide is grown by the instantaneous high temperature and high pressure generated by arc discharge.

Typical products: Aerospace, IT products

Suitable output: Single piece to large batch

Quality: The material has high surface hardness and good wear resistance

Speed: Fast

Applicable Materials

Al, Ti, Zn, Zr, Mg, Nb, and their alloys

Process Cost

Microarc oxidation has high arc starting voltage, high current density, low current efficiency, large energy consumption, and high processing cost, which limits the wide application of this technology.

Impact on the Environment

Micro arc oxidation electrolyte does not contain toxic substances and heavy metal elements. The electrolyte has strong anti-pollution ability and high reuse rate, so it has little environmental pollution.

Examples

13. Metal Drawing

Metal drawing is a surface treatment method to form decorative lines on the surface of the workpiece by grinding the product. According to the different textures after drawing, it can be divided into straight drawing, random drawing, ripple, and swirling.

Typical products: Construction industry such as elevator door panels, faucets, handles, etc., cabinets such as range hoods, sinks, etc.

Suitable output: Single piece to large batch

Quality: Brushing can make the metal surface have a non-mirror-like metallic luster. At the same time, the brushing can also eliminate the slight flaws on the metal surface.

Speed: Fast

Applicable Materials

Metal drawing can be used on almost all materials

Process Cost

The process and the equipment are simple, the material consumption is very low, so the cost is relatively low, and the economic benefit is high.

Impact on the Environment

Pure metal products, the surface is free of paint and any chemicals. 600 degrees high temperature does not burn, does not generate toxic gases, meets fire and environmental protection requirements.

Examples

14. In-Mold Decoration – IMD

The In-Mold Decoration-IMD technology is a kind of molding method that puts the printed film into a metal mold, injects the molding resin into the metal mold and joins the film, so that the printed film is integrated with the resin and cured into a finished product.

Typical products: Decorative and functional control panels for home appliances, car dashboards, air-conditioning panels, mobile phone cases / lenses, washing machines, refrigerators, etc.

Suitable output: Single piece to large batch

Quality: Can be used for complex images, the product is resistant to abrasion, can prevent scratches on the surface, and can maintain the vividness of the color for a long time and is not easy to fade.

Speed: Fast

Applicable Materials

Plastic surface

Process Cost

Just open a set of molds, which can reduce system costs and inventory costs, and reduce costs and man-hours. Highly automated production, simplified manufacturing process, and a one-shot injection molding method that achieves both molding and decoration at the same time, reduces constant cost and man-hours, and enables stable production.

Impact on the Environment

This technology is environmentally friendly and avoids the pollution caused by traditional spray paint plating.

Examples

Mobile phone protective cover for injection molding