The Guide Of Sunning Texture Processing (Etching Processing)

The basic concept of sunning texture processing

What is sunning texture processing?

Sunning texture processing, also known as mold sunburst, embossing, etching, etc., is a processing technique that forms specific texture patterns on the surface of metals, plastics, etc. through chemical corrosion or physical bombardment. The purpose is to improve the performance of the product’s surface, such as enhancing wear resistance, improving slip resistance, and improving the decorative effect, while also covering the surface flaws of the product and improving the overall quality of the product.

The sunning texture processing formed by sunburst processing are diverse and common ones include orange peel texture, lychee texture, wood texture, leather texture, etc. These textures not only make the product surface more beautiful but also can meet specific functional requirements in different application scenarios. For example, using appropriate Sunning texture processing on automotive interior parts can enhance the texture and slip resistance of the interior; conducting sunning texture processing on the handles of medical devices can enhance the grip of doctors during operation and improve the safety of the operation.

The Differences Between sunning texture processing and Traditional Surface Treatment

Sandblasting/Roughening: This process is more mechanical in nature and mainly aims to improve the surface roughness.

Sunmark processing: Achieves high-precision patterns through chemical etching, capable of processing complex designs.

Electroplating/Oxidation: Partially functional protection, with limited decorative effect.

The sun-bleached texture combines both decorative and functional features, offering unique advantages.

Not just about aesthetics – Revisiting the strategic value of sunning texture processing

In the conventional perception of many people, sun-bleaching merely serves to make the product “look more premium” or “feel more comfortable”. Although this view is not comprehensive, it precisely highlights its most obvious value. However, in the highly competitive market of today, the value of sun-bleaching processing has risen to a strategic level.

Enhance the added value of the product and the brand recognition.

An automotive interior with exquisite leather texture, a beauty instrument casing with soft matte finish, and a pair of headphones imitating carbon fiber patterns – these textures instantly distinguish the product from ordinary smooth surfaces. Textures have become the “tactile identifier” of the brand. Without a logo, users can identify the product brand simply by the feel, significantly enhancing brand loyalty and product premium value.

Achieve outstanding functional performance

Enhance grip and anti-slip properties: The textures on the surfaces of tool handles, electric toothbrush handles, sports equipment, etc., can effectively prevent slipping caused by sweat or moisture on the hands, thereby enhancing safety and improving the user experience.

Covering defects and draft lines: After long-term use of the mold or due to uneven shrinkage of the product, there will be surface minor flaws, flow marks, shrinkage marks and draft lines on the smooth surface. These will be extremely obvious on a smooth surface. However, fine textures can skillfully disperse light, perfectly hiding these defects, significantly reducing the scrap rate and improving the production yield.

Changing optical effect and touch sensation: The matte texture can eliminate harsh reflections, providing a soft and elegant visual experience. It is commonly used in high-end electronic products and car panels. Meanwhile, different textures can create a wide range of touch sensations from the smoothness of silk to the roughness of stone.

Optimize user experience and emotional connection

Humans are visual and tactile creatures. A cold, smooth plastic shell and a warm, textured shell bring vastly different emotional responses to users. The embossed processing establishes a deeper emotional connection with the users through the tactile dimension, making the product no longer just a cold tool but a “warm” companion.

Promote design innovation

Designers are no longer confined to a single smooth surface. The sunken lines provide them with a vast canvas for creation. They can infuse products with the wood grain, stone texture, fabric patterns, or futuristic geometric designs, as well as custom logo textures from nature or science fiction, greatly liberating the creativity of industrial design.

Turning the ordinary into the extraordinary – A deep of the technology process for sunning texture processing

The process of fabricating the Sunning texture is an extremely meticulous and precise procedure. Its core lies in selectively corroding the mold steel using chemical solutions. The entire process can be divided into three stages: pre-preparation, mid-etching, and post-processing.

First Stage: Precise Pre-processing

This is the foundation that determines the success or failure of the sun-tanning process. Just as the saying goes, “Sharpening the knife doesn’t hurt the chopping.

Mold Surface Evaluation and Treatment:

Material analysis: Different types of mold steels (such as P20, 718, NAK80, S136, etc.) have different alloy compositions, and their reaction rates and effects to the chemical solution vary significantly. Before applying the treatment, it is necessary to clearly identify the type of steel.

Surface finishing: The mold cavity must undergo precise polishing to achieve a mirror-like finish (such as VDI 3400 #A1). Any original machining marks, scratches or flaws will be magnified after etching, resulting in uneven texture.

Thorough cleaning: Use high-purity solvents (such as acetone, alcohol) for ultrasonic cleaning to ensure that the surface is absolutely free of oil stains, fingerprints, dust, and any other contaminants. Any tiny impurities will cause the etching process to fail.

Texture film design and production:

The texture pattern chosen by the customer (from the texture paper sample or custom design) will be transformed into high-precision film (negative) with different dot densities.

The function of film is similar to that of photographic negatives, and the patterns on it will serve as the blueprint for subsequent photosensitive development. The precision of the film directly determines the clarity and consistency of the final texture.

Phase Two: The Core Etching Process

This is the technical core of the entire process, full of the magic of chemistry.

Spray photosensitive emulsion: Evenly spray a layer of photosensitive photoresist ink (photosensitive emulsion) that is sensitive to specific ultraviolet light onto the clean mold surface, and ensure that the thickness is uniform.

Film lamination and exposure: Carefully laminate the prepared texture film onto the surface of the mold coated with photosensitive glue, and apply vacuum to ensure there are no air bubbles. Then, expose it to ultraviolet light. The transparent parts of the film allow ultraviolet light to pass through and cure (polymerize) the photosensitive glue beneath; the black parts block the ultraviolet light, leaving the photosensitive glue in an uncured state.

Development: The surface is rinsed with a specific developer (usually a weak alkaline solution). The unexposed (uncured) photosensitive adhesive is dissolved and washed away, revealing the underlying mold steel; the exposed (cured) photosensitive adhesive firmly adheres to the mold, forming a protective film. At this point, the designed texture pattern has already appeared on the surface of the mold.

Chemical etching: The developed mold is immersed in etching solution of a specific formula and temperature (usually ferric chloride FeCl₃ solution). The solution corrodes the exposed metal parts not protected by photosensitive glue, while the areas covered by photosensitive glue are protected.

Depth control: Etching depth is a key parameter, which is achieved by controlling the concentration of the etching solution, temperature and etching time. Shallow etching (such as 0.01mm) creates a subtle matte effect, while deep etching (up to 0.1mm or more) produces a strong three-dimensional tactile sensation.

De-gumming and cleaning: After the etching reaches the predetermined depth, remove the mold and use a strong alkaline solution or a special de-film solution to remove the hardened photosensitive gum protective layer on the surface. After thorough cleaning, the texture on the mold surface is permanently formed.

Phase Three: Rigorous Post-processing and Verification

Fine finishing: For very fine textures or deep engravings, a slight manual polishing may be required to remove the burrs produced by etching and ensure smoother demolding.

Comprehensive inspection: Use portable microscopes, roughness testers, 3D profile measuring instruments and other equipment to inspect the depth, uniformity and consistency of the texture to ensure it is in complete accordance with the sample.

Mold testing and verification: The final step is to install the embossed mold on the injection molding machine for mold testing. By injecting actual plastic products, the visual effect, touch feel and demolding performance of the texture are verified in the final application scenario to ensure they meet the design requirements.

The purpose of sunning texture processing

Enhancing aesthetics

Texturing can significantly enhance the visual appeal of products. In the fashion and jewelry industries, the texture of fabrics, leather, or precious metals adds a unique touch. For instance, a textured gold bracelet is more interesting and luxurious than a smooth one. In interior design, textured wallpaper, tiles, and furniture surfaces create a more lively and attractive space.

Improving functionality

Traction and grip
Textures in products such as shoe soles, sports equipment, and car tires can enhance traction and grip. The textured pattern on the bottom of running shoes helps improve the stability of runners and prevent slipping.

Heat transfer
Textured surfaces in heat exchangers and heat sinks can improve heat transfer efficiency by increasing surface area and roughness, promoting more effective heat dissipation.

Anti-reflective
In optical applications, textured surfaces can reduce reflectivity. For example, micro-textured coatings can reduce light reflection in camera lenses and solar panels, thereby improving device performance.

The future development trend of sunning texture processing

With the continuous advancement of technology and the constant changes in market demands, the sunning texture processing technology is also constantly evolving and innovating. In the future, the sunburn processing will exhibit the following development trends

Intelligentization: Introduce automation control technologies and artificial intelligence algorithms to achieve automation and intelligence in the process of fabricating the texture patterns. Through sensors, real-time monitoring of various parameters during the processing is conducted, and based on the monitoring results, the process parameters are automatically adjusted to improve processing accuracy and stability, and reduce labor costs.

Environmental friendliness: With the continuous improvement of environmental awareness, the environmental requirements for surface treatment processes are becoming increasingly strict. Future texture pattern fabricating processes will place greater emphasis on environmental protection, using environmentally friendly corrosion solutions, photosensitive resins, and removal agents, etc., to reduce environmental pollution. At the same time, efforts will be made to treat and recycle wastewater and exhaust gases to achieve green production.

Diversification: In addition to traditional texture patterns, future texture pattern fabricating processes will be able to produce more complex and personalized texture patterns, such as 3D textures, gradient textures, etc. At the same time, they will be combined with other surface treatment processes (such as laser engraving, nano-coating, etc.) to develop more products with excellent performance and unique appearance.

Efficiency: By improving equipment structures and optimizing process parameters, the efficiency of texture pattern fabricating can be enhanced. For example, using multi-station simultaneous processing can significantly shorten the production cycle and increase production efficiency.

Conclusion

In conclusion, sunning texture processing, as an important surface treatment technology, has a wide application prospect in the field of mechanical processing. With the continuous development and innovation of technology, sun-bleaching processing will play an increasingly important role in improving product quality, reducing production costs, and meeting market demands. Relevant practitioners should constantly keep abreast of the development trends of the industry and actively adopt new technologies and new processes to enhance their competitiveness.

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