How Are Surface Textures Formed on Plastic Products?

Texturing on Plastic Product Surfaces: Definition, Principle and Complete Processing Flow

In the production of plastic products, appearance texture directly affects the market recognition of products, and the texturing process is one of the core technologies that determine the surface texture of plastics. Many people may wonder: how are the delicate leather grain on automobile dashboards and the uniform frosted texture on mobile phone back covers made? In fact, these effects essentially come from the texturing treatment on the mold surface. ‌Texturing‌ (also called mold etching or mold graining) is the most widely used mold surface treatment process in the plastic product industry. By processing the designed texture on the mold surface, the injection-molded plastic product can directly replicate the corresponding texture to obtain the desired appearance and tactile effect.

• Core Principle and Process Classification

The core logic of texturing is very clear: first process concave-convex texture on the mold surface, then accurately copy the mold texture to the plastic part through injection molding, and finally let the finished plastic product get the appearance texture that meets the design requirements. Currently, there are two main mainstream processes, which adapt to different accuracy and cost requirements:

1. Chemical Etching Texturing (Traditional Mainstream Process)

This is the most widely used texturing type in the industry at present. The principle is to use chemical agents such as sulfuric acid and nitric acid to react with mold steel. By covering the areas that do not need etching in advance and controlling the reaction time and depth of the chemical agent, the texture with specified depth and style can be obtained in the required area. This process has low cost and is suitable for most conventional product requirements, and it is the first choice for small and medium batch and conventional precision products at present.

2. Laser Texturing (Modern High-Precision Process)

A new process born with the development of numerical control technology. The principle is to use high-energy laser beams to directly etch the mold surface point by point, relying on the numerical control system to accurately control the position, depth and shape of the texture. It can achieve 3D three-dimensional patterns and ultra-fine dense textures that cannot be completed by traditional chemical texturing, with an accuracy of micrometer level. It is mostly used for processing high-end appearance parts and products with complex textures.

• Main Advantages and Functions of Texturing Process

Compared with other surface treatment methods, the advantages of texturing are very prominent, so it has become the mainstream in the industry:

‌Improve appearance texture‌: It can achieve hundreds of different texture effects such as wood grain, leather grain, frosted and geometric grain on the plastic surface, so that ordinary plastic can have the visual and tactile experience close to natural materials, directly get rid of the cheap plastic feeling and improve the product grade.

‌Cover production defects‌: It can cover process defects such as shrinkage marks, weld lines and parting line step differences caused by injection molding, effectively reduce the defective rate and improve production efficiency.

‌Enhance product practical performance‌: After treatment, the surface wear resistance of the part is increased by about 40%. The texture can also increase friction to achieve anti-slip effect, and matte texture can reduce reflection and relieve visual fatigue during long-term use.

‌Outstanding cost performance‌: The texturing cost of a conventional set of molds is only 1,000 to several thousand yuan, and conventional textures can be processed in about 3 days. It has fast speed and stable effect, which adapts to mass production needs.

At present, texturing process has been widely used in various fields such as automotive interiors, home appliance panels, mobile phone and consumer electronics casings, and daily plastic products. Almost all textured plastic products we come into contact with in daily life use texturing process.

• Complete Processing Flow

There are obvious differences in the processing flow of the two different texturing processes, and the specific steps are as follows:

1. Complete Flow of Chemical Etching Texturing

The process of chemical etching texturing has a high degree of standardization, and it is divided into 10 core steps in total: ‌Mold preparation (degreasing and cleaning) → mold fixing → chemical inspection → surface leveling pretreatment → texture transfer printing → pattern trimming → chemical etching → post-treatment cleaning → QC inspection → anti-rust packaging‌

• ‌Mold preparation‌:

Thoroughly degrease and clean the processing mold to remove residual release agent, oil stains, rust and other impurities on the mold surface, ensure the surface is clean and flat, and provide a qualified substrate for subsequent processing.

• ‌Pre-inspection and fixing‌:

After fixing the mold on the processing table, conduct chemical inspection on the mold steel composition to confirm that the steel properties meet the etching requirements, avoid affecting the final texture effect due to steel impurities, and then level the protrusions and scratches on the mold surface.

• ‌Texture transfer and trimming‌:

Transfer the pre-designed texture pattern to the mold surface, and then manually trim the edge details of the pattern to ensure that the texture contour is clear without defects such as dislocation and burrs.

• ‌Core etching processing‌:

Configure chemical agents with corresponding concentration, and selectively etch the areas on the mold surface that need texture, and obtain the texture depth required by the design by controlling the corrosion time.

• ‌Post-processing and delivery‌:

After etching, thoroughly clean the residual chemical agents and corrosion residues on the mold surface, and secondary trim the texture edges. Then the QC department inspects whether the texture depth and contour uniformity meet the design requirements. After reaching the standard, the mold is treated with anti-rust and packaged and delivered to the injection molding manufacturer.

2. Complete Flow of Laser Texturing

Laser texturing has a simpler process flow and more accurate accuracy control, and it is divided into 8 core steps in total: ‌Degreasing and cleaning → digital texture drawing → sample proofing on waste blank → formal laser processing → gloss adjustment → QC inspection → anti-rust treatment → packaging and delivery‌

• ‌Preparatory work‌:

 Consistent with chemical etching texturing, first thoroughly degrease and clean the mold to remove surface impurities and ensure that laser processing is not interfered by impurities.

• ‌Design and sample confirmation‌:

Import the digital file of the designed texture into the numerical control system of laser processing, first make a sample on a waste blank of the same material as the mold, confirm the parameters such as texture effect, laser power and processing speed, and then start processing the formal mold.

• ‌Core laser processing‌:

The numerical control system controls the high-energy laser beam to scan and etch the mold surface point by point, accurately control the depth and shape of each texture, and the automatic processing does not require manual intervention, and the accuracy is much higher than that of traditional chemical texturing.

• ‌Post-processing and delivery‌:

After processing, adjust the gloss of the texture according to the design requirements, then QC inspects whether the texture accuracy meets the requirements. After passing the inspection, do anti-rust treatment, package and deliver.