Introduction:

Surface treatment is the most important consideration in industrial product design. The product casing protects the internal parts of the product and has a great deal to do with the tactile feel and texture of the product.

It also plays a very critical role in improving the external image of the product. The shell materials of most products are plastic, common metals (aluminum / stainless steel), and glass. Therefore, the surface treatment processes for these materials are more critical.

Product design, materials, manufacturing process, and processing technology are key factors relating to the design and processing of industrial products. The shape of the product casing should be designed ergonomically and in accordance with the requirements of the product’s internal structural design.

The design should be simple, new, and aesthetically pleasing to achieve the desired visual effect while keeping in mind the function of the product.

Therefore, the problem of the product surface treatment process will inevitably be involved in the production process. In addition, the shape of the product casing should be designed in such a way that it is not too complex it and should be as easy to manufacture as possible, thus making it easy to produce.

However, in industrial product design, there are a variety of problems that, if not handled properly, can have a negative impact on the product casing. Today Ruizhi sourcing will briefly discuss the 26 types of surface treatments for product casings and these methods’ advantages and disadvantages.

1. Anodic Oxidation

In order to overcome the defects in the surface hardness and wear resistance of aluminum alloys, expand the range of applications, and extend the lifespan, surface treatment technology has become an indispensable part of the use of aluminum alloys, and anodic oxidation technology is the most widely used and the most successful.

The metal component parts of the plastic toys are made of anodized aluminum alloy, which is cut flat and polished smooth to provide maximum personal protection for the main target group — children. The metal components are resistant to wear and stains and are aesthetically pleasing.

Advantage:

The film produced by the anodic oxidation is durable and wear resistant.

Disadvantage:

It takes a long time to do the anodic oxidation, often several tens of minutes.

2. Micro-arc Oxidation

Micro-arc oxidationis also known as micro-plasma oxidation. It is based on the formation area of common anodic oxidation and uses a high voltage discharge, which allows a modified ceramic coating on the surface of aluminum and magnesium and its alloys by the instantaneous high temperatures and pressure of the arc discharge.

The modification can simply be understood as changing its properties. To put it bluntly, what is not wear-resistant becomes wear-resistant and what is not corrosion-resistant becomes corrosion-resistant, which is equivalent to a rebirth.

Advantages:

1. Excellent wear resistance

2. Excellent corrosion resistance

3. Easy process, high manufacturing efficiency

4. Even thickness and tone

5. Electrolyte is weakly alkaline, which will not pollute the environment.

Disadvantages:

1. The process of micro-arc oxidation film formation is quite complex and the mechanism is not well studied.

 

3. Metal Hairline Finish

Metal hairline finish is a surface treatment method that forms lines on the treated surface of the workpiece by grinding products to achieve a decorative effect. Depending on the pattern of the hairline finish, it can be divided into the straight hairline finish, messy hairline finish, corrugation pattern, and rotation pattern.

Applicable materials:

Almost all metal materials can be used in the metal hairline finish process.

Process cost:

Simple process method, simple equipment, small material consumption, relatively low cost, and high economic efficiency

Environmental impact:

The product is pure metal. The surface is free of paint and any chemical substances and it will not burn at 600 degrees. It also does not produce toxic gas. It meets the environmental requirements for fire protection.

Metal hairline finish process	Effect after stainless steel hairlline series

4. Enameling

Enameling is done by filling the entire body with the color glaze and then baking it in a blast furnace at a temperature of approximately 800°C. The color glaze melts from a granular solid to a liquid, and when cooled, it becomes a brilliant color glaze fixed to the body.

As it is lower than the height of the copper wire, it has to be coated again with a color glaze and then sintered, this generally has to be done four or five times in succession until the pattern is filled in to level with the filigree pattern.

              

5. Shot Peening

Shot peening is a cold working process that uses shots to bombard the surface of the workpiece and produce residual compressive stresses to enhance the fatigue life and strength of the workpiece.

6. Sandblasting

Sandblasting is a process of cleaning and roughening the existing workpiece surface of the substrate by the impact of high-speed sand flow, that is, using compressed air as power to form a high-speed jet beam to spray the blasting material (copper ore, quartz sand, emery sand, iron sand, Hainan sand) at high speed to the surface of the workpiece to be treated, in order to change the appearance or shape of the outer surface of its surface change…

7. Etching

Etchingis a technique that uses chemical treatment or physical impact to remove materials.

This is also commonly referred to as photochemical etching, which refers to the removal of the protective film from the area to be etched after plate making and development, as well as the contact with chemical solutions during etching, to produce the effect of dissolving and corroding, creating unevenness or hollowing out.

Etching process	Stainless Etching Effect

8. In-Mold Decoration Technology

IMD is In-Mold Decoration (In-Mold Decoration technology), also known as coating-free technology. Basically, Surface decoration technology that consists of a hardened transparent film on the surface, a printed pattern layer in the middle, and an injection layer on the back, with a layer of ink in the middle to make the product resistant to friction. It can also prevent the surface from being scratched and can keep the color vivid and not easy to fade for a long time.

The in-mold labeling is mainly used on blow-molded and injection-molded products made of PP, PE, PET, and other materials. Before blow molding and injection molding, the printed labeling is inserted into the cavities of the blow molding and injection molding. When the mold is closed for blowing and injection, the special adhesive on the in-mold labeling is melted by the high temperatures and pressure in the mold, and the surface of the bottle or injection molded part is fused into one. When the mold is opened, a beautifully printed bottle or injection part is completed at once.

Advantages:

New and stylish appearance; anti-counterfeiting function; safe and environmentally friendly; not easy to fall off and damage; reinforced side walls; high efficiency and effectiveness

Disadvantages:

1. Professional injection molding machines are required for production.

2. Professional printing machines are required for in-mold labeling.

9. OMD

OMD is short for “Out Mold Decoration”. It is the integrated display of vision, touch, and function. It is an exterior decorative technology that is an extension of IMD, which is a 3D surface decoration technology that combines printing, texture structure, and metallization characteristics.

10. Laser Engraving

Laser engraving is also called laser engraving or laser marking, which is a process of surface treatment using optical principles. Lasers are used to engrave permanent marks on materials or inside transparent materials.

11. Electrical Discharge Machining (EDM)

Electrical discharge machining (EDM) is a special machining method that uses the electric erosion effect generated by the pulse discharge between the two electrodes immersed in the working fluid to ablate conductive materials. It is also called spark machining or spark eroding, abbreviated as EDM in English.

Commonly used as tool electrodes are electrically corrosion resistant materials with high conductivity, high melting point and easy processing, such as copper, graphite, copper-tungsten alloys and molybdenum. During processing, the tool electrode also has losses, but they are less than the amount of metal removed from the workpiece, or even close to no losses.

12. Laser Texturing

Laser texturing uses a high-energy-density laser to react with the steel surface to form snakeskin/etched patterns/pear ground or other forms of patterns.

Laser texturing uses laser ablation to selectively remove materials from specific surface areas. By adjusting the laser’s parameters, we’re able to control how much surface is removed as well as create different patterns. This typically increases roughness, creating surface textures that can easily lodge adhesives and provide an additional anchoring surface.

To reach the material’s ablation threshold, pulsed lasers concentrate energy to reach high peak power. Typically, the pulse duration is 100 nanoseconds, and each pulse contains between 0.5 and 1 millijoule. The time required to texture a surface depends on the material, the desired roughness level, and the laser system’s output power.

13. Pad Printing

Pad printing is one of the special printing methods. Steel (or copper, thermoplastics) gravure is used along with a curved rubber printing head. Dip the ink on the gravure onto the surface of the printing head, and then you can print text, patterns, etc. On the surface of the object, you need to press.

It is capable of printing text, graphics, and images on irregularly shaped object surfaces and is now becoming an extremely popular type of special printing. For example, texts and graphics on the surface of mobile phones are printed in this way. This is also true of the surface printing of many electronic products such as computer keyboards, instruments, and meters, and texts and graphics on small, concave, and convex surface toys are finished with pad printing.

Advantages:

Simple process; the advantages of printing on small, concave, and convex surfaces are obvious.

Disadvantages:

Pad printing inks are easily affected by factors such as temperature, humidity, and static electricity, this can lead to print defects such as uneven ink adhesion and lack of durability of the printed image.

14. Screen Printing

Screen printing is is a process that uses silk fabric, synthetic fiber fabric, or metal mesh on the screen frame, and uses hand-carved lacquer film or a photochemical plate-making method to produce a screen printing plate.

Modern screen printing technology uses photosensitive materials to produce screen printing plates by means of photographic plate making. (Make the screen holes of the graphic part of the screen printing plate through holes, while the screen holes of the non-graphic part are blocked.) When printing, the ink is transferred to the substrate through the mesh holes of the graphic section by squeezing of the squeegee, creating the same graphic as the original.

15. Direct Thermal Printing

Direct thermal printing is a method in which a thermal agent is applied to paper to make thermal recording paper, and the thermal recording paper, under the action of heat, causes physical or chemical property changes in the substance (color developer) to obtain an image.

16. Heat Transfer Printing

The principle of heat transfer printing is to print a digital pattern on a special transfer paper with a special transfer ink through a printer, then use a special transfer machine to accurately transfer the pattern to the surface of the product at high temperature and pressure to complete the product printing.

Heat transfer printing is an emerging printing process. The process printing method is divided into two major parts: transfer film printing and transfer processing. Transfer film printing uses dot printing (resolution up to 300 dpi) to pre-print the pattern on the film surface. The printed pattern is richly layered, colorful, and varied, with small color differences and good reproducibility, this can achieve the effect required by the designer of the pattern and is suitable for mass production.

The transfer process is a one-off process (heating and pressure) by means of a heat transfer machine to transfer the beautiful patterns on the transfer film to the product surface. After forming, the ink layer is integrated into the product surface, making it realistic and beautiful, and greatly enhancing the product’s grade.

The heat transfer printing process is used on a variety of product surfaces such as ABS, PP, plastic, wood, and coated metal. It is widely used in clothing, plastic, cosmetics, toys, electrical appliances, building materials, gifts, food packaging, stationery, and other industries.

Advantages:

The printed patterns are multi-layered and colorful; they are suitable for mass production.

Disadvantages:

The technical content of the process is relatively high. Many materials need to be imported.

17. Lithography

Because the graphic part of lithographic printing is on the same plane as the non-graphic part, during printing, a separation of oil and water is used to distinguish the pattern part from the non-pattern part of the printing plate.

The component supplies water to the non-graphic part of the printing plate, preventing the non-graphic part from being wetted by the ink. Then, the ink supply device of the printing part supplies ink to the printing plate.

Since the non-graphic part of the printing plate is protected by water, the ink can only be supplied to the graphic part of the printing plate. Finally, the ink on the printing plate is transferred to the nipple, then the pressure between the blanket cylinder and the impression cylinder is used to transfer the ink on the nipple to the substrate. This completes a printing. Therefore, lithography is a kind of indirect printing method.

18. Curved Surface Printing

Essentially, curved surface printing involves putting the ink into the intaglio with engraved characters or patterns, which are then copied onto the curved surface, and then using the curved surface to transfer the characters or patterns to the surface of the finished product, which is then cured with heat treatment or ultraviolet light.

19. Hot Foil Stamping

Hot foil stamping, commonly known as “foil stamping”, refers to the stamping of text and patterns on surface of the material such as color foil on the first or fourth cover of the hardcover book case and on the back part of the book or embossing various convex and concave book titles or patterns by hot pressing.

20. Water Transfer Printing

Water transfer printing is a kind of printing that uses water pressure to hydrolyze transfer paper/plastic film with color patterns. The technological process includes the production of water transfer decal paper, the immersion of the paper, the transfer of the pattern, the drying, and the finished product.

Water transfer technology is the latest digital imaging technology that surpasses any imaging technology approach. It uses special paper made of nanomaterials and special environmentally friendly inks to print images on any solid medium. It is suitable for printing on the surface of hardware, plastic, leather, glass, ceramics, wood, and other products (cloth and paper are not applicable), regardless of the shape of the product. Very complex, extra-large areas, extra-long, and extra-wide products can also be decorated.

Its greatest technical advantages are that it does not require special equipment, is not limited by the medium, does not require special consumables, and requires no high-temperature heating. As long as you have an image input tool (scanner or digital camera), a drawing tool (computer), an image output tool (inkjet printer), plus water transfer ink and water transfer paper, you can print any image you want on any solid object, on any curved surface, in vivid colors, and with absolute photo quality. It is applicable to all areas.

Advantages:

Low cost, quick to get started, easy to operate.

Disadvantage:

Image transfer is easily distorted.

21. Flat-screen Printing

For flat-screen printing, the printing mold is a polyester or nylon screen (floral version) fixed on a square frame with a hollow pattern.

The patterned areas of the plate are permeable to the color paste, while the non-patterned areas are closed with a polymeric film layer. When printing, the plate is pressed against the fabric and the plate is filled with color paste, this is scraped back and forth with a scraper to make the color paste reach the surface of the fabric through the pattern.

22. Calendering

Calendering, also called calendaring, is the final process in finishing of heavy leather. The plasticity of the fiber under mixed heat conditions is used to flatten the surface of the fabric or roll out parallel fine diagonal lines. This enhances the finishing process of the fabric gloss. After the material is fed, it is heated and melted, then formed into a sheet or film, and then cooled and rolled up. The most commonly used calendaring material is polyvinyl chloride.

23. Paint Spraying

Paint spraying generally refers to spray coating. It is a coating method in which a uniform and fine mist are dispersed by pressure or centrifugal force through a spray gun. This mist is applied to the surface of the object to be coated. Common decorative colors on toy surfaces are applied by spray painting.

Using spray coating technology, coatings with physical and chemical properties such as wear resistance, corrosion resistance, thermal insulation, electrical conductivity, insulation, sealing, lubrication, and other special machinery can be obtained on a variety of substrates. It is used in a wide range of applications, including toys, hardware, plastics, home furnishings, and military and marine industries.

Paint spraying is a process used primarily for model toys, electronic cartoon toys, and assembled toys, Painting the surface of toys gives them a variety of colors. The protective properties and experience of the paint also enhance the experience of using the toy and the tactile sensation of the hand.

Advantages:

High production efficiency in spraying, suitable for manual work and automated industrial production

Disadvantages:

Paint mists and evaporating solvents not only pollute the environment and are harmful to human health, but also waste paint and cause economic losses.

24. Electroplating

Electroplating is the process of applying a thin layer of other metals or alloys to the surface of certain base metals using electricity and chemical reactions.

The various types of electroplating use electrolysis to attach a metal film to the surface of a base metal or other material to prevent oxidation (e.g. rusting). It improves the wear resistance, electrical conductivity, reflectivity, and corrosion resistance of metals and has an aesthetic-enhancing effect. Many of the outer layers of the coins are also electroplated.

The purpose of electroplating is to apply a metallic coating to a substrate, changing the surface properties or dimensions of the substrate. Electroplating enhances the corrosion resistance of metals (plated metals are mostly corrosion resistant), increases hardness, prevents wear, and improves electrical conductivity, smoothness, heat resistance, and surface aesthetics.

The ABS plastic parts of the toys can be electroplated. Electroplating chrome on the ABS plastic parts of the toy is a good way to achieve a metallic feel while reducing the product’s weight. In principle, all plastics can be electroplated, but ABS plastics are usually used in terms of plastic properties and plating adhesion.

Advantages:

Reduced weight; overall cost savings; fewer machining processes; simulated metal parts

Disadvantages:

Metal inserts cannot be changed during the molding process. There is a risk of fire when electroplated plastics are used in certain types of household appliances.

25. UV Printing

UV printing process mainly refers to the use of special UV inks to achieve partial or overall UV printing effects on UV printers. It is mainly suitable for printing on non-absorbent materials. The advantages of UV ink are instant and fast curing, no volatile organic solvents VOC, low pollution, high efficiency, and low power consumption. UV printing is a printing method that uses UV ink for printing and dries using ultraviolet light. UV printing is mainly used for packaging printing on laser paper, aluminized paper, and non-absorbent materials such as plastic PE granules and PVC.

Compared with traditional offset printing, UV printing has the characteristics of brilliant colors, special substrate materials, novel products, and broad market prospects, and is suitable for high-end business cards, high-end commercial albums, special calendars, special label printing, and other product areas.

UV printers can print on all types of metal, also aluminum veneer, ceramics, crystal, ABS, organic glass, acrylic, PVC, plastic, wood products, leather, stone material, toys, USB flash drive, decorative materials, art glass wall, artistic ceiling, rechargeable battery, cell phone case, wine boxes and bottles, signs and labels, indoor and outdoor advertising, background wall, product logo, gifts with logo printing and other material objects, soft and durable objects.

Advantages:

UV printing uses imported UV ink, which is instantly dry and has superior print fastness.

Disadvantages:

The printheads of UV flatbed printers can easily become jammed. The oscillation speed slows down, causing slow printing. UV printers cannot recognize black ink cartridges.

26. Powder Coating

Powder coating is a method of surface treatment in which plastic powder is sprayed onto parts. The advantages of this technology are superior technology, energy conservation and high efficiency, safety and reliability, and brilliant color, compared to ordinary paint spraying surface treatment. Therefore, Thus, it is widely used in the field of light industry and household decoration.

Under the action of the electric field, the paint is sprayed onto the workpiece. The plastic powder is evenly adsorbed to the surface of the workpiece to form a powdery coating. The powder coating is flattened and cured after high-temperature baking, and the plastic particles will melt into a dense final protective coating with different effects that adhere firmly to the surface of the workpiece.

Advantages:

No pollution to the environment, non-toxic to humans; short spraying construction time; high corrosion and wear resistance of the coating; easy construction; lower cost than the paint spraying process.

Disadvantages:

Powder coatings products do not allow water leakage; do not allow rust; do not allow bruising and deformation.

Conclusion：

These 26 kinds of surface treatment processes cover most of what product engineers’ requirements. The above introduction belongs to the basic knowledge of surface treatment. This is because each surface treatment method is very complex and involves operation steps, raw materials, temperature, applicable materials, advantages and disadvantages, and so on.

If you want to study surface treatment methods in more detail or want to try a surface treatment process on your own products, you can leave a message on our blog or contact us. Hallosourcing will bring you more knowledge sharing.