Skin texture, also known as grain etching or texturing, is the core process determining the texture, touch and appearance grade of automotive interior parts, widely applied to instrument panels, door panels, center consoles, armrests and other components. It can simulate leather, matte and brushed textures, and cover molding defects such as flow marks, sink marks and weld lines. The processing precision and repair quality of skin texture directly affect the yield and durability of interior parts, requiring refined control from processing technology, preliminary preparation, defect repair to daily maintenance.
1. Core Process and Types of Skin Texture ProcessingChemical etching and laser engraving are two mainstream processes for automotive interior mold skin texture, adapting to different texture precision, complexity and cost demands. Traditional chemical etching forms preset micro concave-convex textures by corroding mold cavity surface with acidic corrosive liquid, featuring low cost and adaptability to large-area complex curved surfaces, suitable for conventional textures such as lychee grain, fine sand grain and leather grain. The process includes mold pretreatment, film masking, exposure, development, etching, cleaning and post-treatment.
Laser engraving adopts 3D laser marking machine for micron-level engraving with high positioning precision, accurately reproducing delicate leather grain, geometric grain and bionic texture. It has no chemical pollution and high processing efficiency, suitable for high-end vehicle interior and high-precision texture.
Common skin texture types include soft and comfortable leather grain as the first choice for mainstream interior; matte fine sand grain with matte texture and strong defect covering performance for large-area panel; technological brushed and geometric grain for decorative strips and functional areas; wood grain and carbon fiber bionic grain for mid-to-high-end decorative parts to enhance luxury sense.
2. Key Preliminary Preparation for Skin Texture ProcessingMold steel selection determines skin texture effect directly. Automotive interior skin texture molds prefer 718H, P20 and NAK80 pre-hardened mold steel with uniform structure, good polishing performance and low impurity content, avoiding low-quality steel causing pinholes, pitting and uneven texture depth. Increase demolding draft angle in skin texture areas. The deeper the texture, the larger the draft angle, preventing demolding pulling damage and texture wear. Conduct fine polishing on mold cavities before texturing to remove CNC tool marks, electric discharge lines, surface rust spots and sand holes, as any surface defects will be amplified after etching. Make clear zoning between textured and smooth areas with neat boundary lines for natural transition.
Confirm texture samples before processing. Three parties including vehicle manufacturer, mold factory and texture factory lock texture style, depth, gloss and hand feel standards, retain standard comparison samples as the reference for subsequent processing and repair.
3. Standard Processing Flow and Quality Control of Skin TextureThe standard process of chemical etching includes thorough degreasing and cleaning of mold cavities to remove oil, dust and impurities, ensuring clean and dry surface. Attach high-precision film mask in dust-free environment to eliminate bubbles and folds for complete fitting of curved surfaces. Complete UV exposure curing and chemical development to expose areas to be etched, then immerse in corrosive liquid at constant temperature for fixed time corrosion molding. Take out after reaching set texture depth, complete cleaning, acid-base neutralization, drying and rust prevention.
Quality inspection controls three dimensions of appearance, hand feel and precision. The overall texture is uniform and clear without missing grain, dislocation and color difference with neat boundary; delicate hand feel without burr and scratching; consistent texture depth and surface roughness. The molded product can completely reproduce texture without demolding pulling damage and texture deformation.
4. Common Skin Texture Defects and Repair MethodsLong-term mass production easily causes surface scratches, texture wear, local corrosion pitting, texture collapse, color difference and missing grain. Adopt corresponding repair methods according to damage degree. Slight shallow scratches, surface wear and uneven color can be gently polished with fine sandpaper and abrasive paste for local texture fine-tuning without obvious repair traces. Moderate deep scratches, local missing grain and corrosion pits can be repaired by argon arc welding with the same material, polished flat after welding, then re-etched or laser engraved locally referring to original samples to ensure consistent texture trend and depth.
For severe aging, cracking and overall wear of large-area texture, polish off old skin texture overall, re-polish cavities and carry out grain etching or laser engraving again according to original process. Replace inserts directly if mold cavity matrix is severely deformed with excessive repair cost. Conduct mold trial verification after all repairs to confirm product appearance and texture reproduction effect meet standards before mass production.
5. Daily Maintenance of Textured MoldsDaily maintenance is the key to extending mold service life. Reasonably control injection temperature, pressure and speed during production to avoid texture wear and deformation aggravated by high temperature and pressure. Clean cavity surface after each shift to remove plastic residue, oil and dust, preventing hard impurities from scratching skin texture by long-term friction. Conduct rust prevention treatment after cleaning and drying when molds are idle for a long time, store in dry and dust-free environment to avoid moisture rust and texture corrosion. Prohibit hard tools from directly touching textured areas during mold handling and disassembly to prevent artificial collision and scratching. Regularly inspect texture wear status and handle minor defects in a timely manner to avoid fault expansion affecting mass production.
