To improve the quality of silicone products from molding to surface treatment, the core lies in optimizing process parameters, controlling key links, and standardizing quality inspections. Below is a detailed breakdown:
1. Molding Process Optimization (Foundation of Quality)
Raw Material Control: Select high-purity silicone rubber (e.g., vinyl silicone rubber with vinyl content 0.15%-0.3% for general products, or high-phenyl silicone rubber for extreme environments) and compatible curing agents (peroxide curing agents for general use, platinum curing agents for medical-grade products). Preprocess raw materials by drying at 60-80℃ for 2-4 hours to remove moisture, avoiding bubbles in finished products.
Mold Preparation: Use precision-machined molds with surface roughness Ra ≤ 0.8μm to ensure product surface smoothness. Apply a high-temperature resistant release agent (silicone-based or fluorine-based) evenly before molding, preventing product adhesion and surface scratches. Regularly maintain molds to repair wear, deformation, or residue buildup.
Molding Parameter Tuning: For compression molding, control temperature at 160-180℃, pressure at 10-30MPa, and curing time at 3-10 minutes (adjust based on product thickness: 1-2 minutes per mm). For injection molding, set barrel temperature at 120-150℃ (avoid overheating to prevent rubber degradation), injection pressure at 50-100MPa, and mold temperature at 150-170℃. Ensure uniform rubber flow to avoid defects like uneven thickness or missing corners.
De-molding & Post-Curing: Demold gently using professional tools to prevent product deformation or damage. Conduct post-curing at 200-220℃ for 2-4 hours for critical products (e.g., medical or aerospace parts) to eliminate residual volatile substances (VOCs) and improve mechanical properties (tensile strength ≥ 5MPa, elongation at break ≥ 300%).
2. Post-Molding Secondary Processing (Defect Correction & Precision Enhancement)
Trimming & Deburring: Use laser trimming (for precision parts with tolerance ±0.01mm) or ultrasonic trimming (for mass-produced products) to remove flash and burrs. Avoid manual trimming for complex structures to prevent dimensional deviations.
Dimensional Inspection: Employ 3D scanners or coordinate measuring machines (CMM) to check key dimensions (e.g., seal ring inner diameter, product thickness) against design drawings. Reject products with deviations exceeding ±0.05mm (stricter for high-end fields like medical devices: ±0.02mm).
Defect Repair: For minor bubbles or pinholes, use silicone repair paste matching the base material for filling and curing. For serious defects (e.g., cracks, incomplete molding), scrap the product to avoid affecting overall performance.
3. Surface Treatment (Functional Upgrade & Quality Improvement)
Cleaning Pretreatment: Use ultrasonic cleaning with neutral detergent (pH 6-8) at 40-60℃ for 10-15 minutes to remove oil, dust, or residual release agent on the surface. Rinse with deionized water and dry at 80-100℃ to ensure surface cleanliness (surface tension ≥ 38 mN/m).
Functional Surface Treatment:
Plasma Treatment: Use oxygen or argon plasma to etch the surface, increasing roughness and adhesion. It is suitable for products needing bonding (e.g., silicone rubber bonded to plastic or metal) and can improve bonding strength by 30%-50%.
Coating Treatment: Apply silicone oil (for lubricity) or wear-resistant coatings (e.g., PTFE coatings) to the surface. The coating thickness is controlled at 5-20μm to enhance wear resistance (wear volume ≤ 0.1mm³ after 10,000 friction cycles) or reduce friction coefficient (≤ 0.2).
Electroplating (for Special Needs): Conduct electroless plating of nickel or copper on the surface for electronic products requiring conductivity. Ensure plating uniformity (thickness deviation ≤ ±1μm) and good adhesion (pass the 3M tape peeling test without shedding).
Post-Treatment Inspection: Check surface finish (no scratches, uneven coating), functional performance (adhesion, lubricity, conductivity), and conduct aging tests (high temperature 150℃ for 1000 hours or ultraviolet irradiation for 500 hours) to verify surface durability.
4. Quality Control System (Full-Process Guarantee)
Establish SOPs (Standard Operating Procedures) for each link, training operators to ensure process consistency.
Conduct random inspections of semi-finished products (10% sampling rate for molding, 5% for surface treatment) and 100% inspection of finished products.
Record raw material batches, process parameters, and inspection results for traceability, facilitating defect analysis and improvement.
