Mold Texturing

The texturing process is called "sun texturing" in Hong Kong, "bite texturing" in Taiwan, and "etching" in formal terminology. Its English name is "texture" or "texturing". As more and more plastic products fill our lives, people are increasingly reluctant to see them look like "plastic" products. Therefore, mold decoration using the etching process is more in line with people’s preferences.

【Purpose of Texturing】

Improve the appearance of products. Through texturing, it can cover defects such as shrinkage marks, weld lines, as well as step marks on parting surfaces and slider structures.

Enhance the surface strength of parts after texturing and sandblasting procedures.

Boost the appearance texture of plastic parts, enabling products to present diverse or brand-new designs.

【Principle of Texturing】

Chemical solutions (such as sulfuric acid, nitric acid, etc.) are used to react with mold steel, and the reaction process is controlled to achieve a variety of texture effects.

【Texturing Process Flow】

Mold Preparation → Film Exposure → Film Lamination → Exposure → Etching → Cleaning → Post-treatment

【Types of Textures】

Sand-pattern

Satin-pattern

Leather-pattern

Stone pattern

Geometric pattern

HANDS pattern

HN3D pattern, etc.

【Texturing Procedures】

Cleaning: Clean the surface of the mold cavity thoroughly to remove surface oil.

Masking: Cover the cavity surfaces that do not require texturing with adhesive tape or apply anti-corrosion paint to prevent etching. This is the most time-consuming procedure. There are three common masking materials:

Thick adhesive tape: Used to cover most of the cavity surface.

Thin adhesive tape: Used for masking detailed areas, such as arc edges.

Anti-corrosion paint: Used for areas that cannot be covered by adhesive tape, such as complex curved surfaces.

Drying: Dry the anti-corrosion paint.

Surface Treatment: Wipe the cavity surface to be textured carefully with absorbent cotton to ensure no impurities or dirt remain, thus guaranteeing the texturing effect.

Texturing: Spray paint on the cavity surface to be textured, then immerse it in the etching solution. During the etching process, observe the texturing condition and repeat the immersion until the desired texturing effect is achieved.

Sandblasting: Sandblasting serves two purposes. First, it removes residual solution on the cavity surface (before this, rinse with ammonia water and air pressure). Second, it adjusts the gloss of the texture—different gloss levels can be achieved by using different sand particles and pressures.

Subsequent Procedures: Clean the cavity surface thoroughly, apply anti-rust agent, and then send the mold parts back to the mold manufacturer.

【Requirements for Molds Before Texturing】

The work done on the mold before etching plays a crucial role in the texturing effect, so no details should be overlooked:

Draft Angle Requirement (for heights below 500mm): At least 1 degree is required for every 13μm (except for special textures).

Polishing Requirement:

For a texture depth of approximately 5μm: Use sandpaper with a grit size of 1200 or higher.

For a texture depth of approximately 10μm: Use 1000-grit sandpaper.

For a texture depth of approximately 25μm: Use 800-grit sandpaper.

For a texture depth greater than 50μm: Use 600-grit sandpaper.

Parting Line Treatment: It is recommended to leave a margin of at least 0.2 to 1mm. If electroplating is required after texturing, it is recommended to increase the texture depth by 10μm.

Mold Surface Requirements Before Texturing: No machining marks, no welding points, no polishing marks, no EDM (electrical discharge machining) marks; the mold surface must have appropriate smoothness and etchability.

【Common Problems After Texturing】

After texturing, the cavity surface becomes rough, and the most common problems are mold sticking (pulling) and sticking to the front mold. In some areas, due to the originally small draft angle, the draft angle becomes even smaller (or even negative) after texturing, leading to mold pulling. During ejection, poor demolding often causes "ejection whitening" (stress whitening at ejection points), which significantly affects the product’s appearance.

To solve the mold pulling problem:

Polish the textured surface to reduce the texture depth and eliminate sharp angles caused by texturing, ensuring smooth demolding.

In actual production, since it is difficult to solve demolding issues by adjusting machine parameters, mold release agents are usually applied to the textured surface during production.

From the mold design perspective, the problem can be improved by increasing the draft angle of the mold-pulling surface and adding more ejector pins.