Router plastic casing works as exterior decoration, mechanical protection, auxiliary heat dissipation and internal component fixing carrier for network communication equipment. Featured with thin wall, dense openings and integrated buckle structure, such plastic parts impose strict requirements on raw material selection, mold precision and process tuning in China’s consumer electronic injection industry. Injection molding dominates mass production for its high forming efficiency, stable dimensional accuracy and controlled production cost, yet thin-wall structural characteristics easily trigger various molding flaws without refined process control. This paper analyzes the whole manufacturing flow from raw material selection, pre-production pretreatment, core injection cycle, post-processing to common defect optimization based on actual domestic molding experience.
1. Raw Material Selection & Property Requirements for Router Shells
Continuous heat generation from built-in circuit boards and daily bump, scratch together with electronic safety standards decide core material indicators of flame retardancy, insulation and thermal stability. ABS and PC+ABS alloy remain mainstream molding feedstock for domestic router production with differentiated application scenarios.
Conventional ABS boasts favorable melt fluidity, easy machining performance, smooth surface and uniform color dispersion, which fits cost-effective low-end household router casings with basic rigidity and impact resistance. PC/ABS composite inherits PC’s high heat resistance and flame retardancy as well as ABS’s outstanding molding performance, effectively avoiding yellow discoloration and brittle fracture after long-term high-temperature operation, which is widely adopted for mid-to-high-end commercial communication equipment shells. All base plastics add environment-friendly flame retardant to reach UL94 V0 grade and domestic electronic insulation standard; strict moisture restriction is essential to avoid silver lines, inner bubbles and cracking caused by over-hydrated pellets.
2. Pre-molding Pretreatment of Raw Plastic Pellets
Pre-processing including drying, color mixing and impurity filtration lays foundation for stable finished quality. Drying parameters differ for varied materials: ABS is dried at 70℃ to 80℃ for 2–4 hours with hot-air dryer, while PC+ABS needs 80–90℃ drying lasting 4–6 hours to remove internal residual moisture completely.
Color mixing adopts specialized color masterbatch blended via high-speed mixer to ensure consistent batch color and eliminate uneven stain on shell surface. Sieving procedure filters agglomeration and foreign impurities to stop mold abrasion and surface scratch on finished plastic parts.
3. Core Injection Molding Production Procedures
Router thin-wall molding consists of six standard phases: mold closing, injection filling, packing, cooling, mold opening and ejection, each parameter directly determines dimensional precision and exterior quality.
Low-speed low-pressure mold closing protects precise mold cavity from impact damage and eliminates overflow flash caused by poor fitting parting surface. Segmented injection is adopted for thin-wall feature: low flow rate fills runner, medium high speed fills whole cavity and terminal low speed supplements shrinkage, with injection pressure controlled within 80–120MPa to prevent short shot. Packing starts immediately after cavity full filling under slightly lower pressure than injection, sustaining 10–20 seconds to compensate volume shrinkage and remove surface sink mark. Circulating cooling water keeps cooling period between 20–30 seconds for full shaping and anti-warpage, then balanced ejection structure pushes finished shell out slowly to avoid cracking of thin-wall structure.
4. Post-finishing Process after Molding Demolding
Demolded semi-finished router shells need refined post-treatment to meet delivery criteria. Flash trimming removes burrs on parting line, buckles and holes via freezing trimming equipment or manual polishing for smooth edge finish. Appearance classification screens defective goods with bubble, scratch, deformation and chromatic aberration. High-end products optionally receive oil spraying, frosted treatment and laser engraving to upgrade surface wear resistance and hand feel. Final dimensional inspection uses caliper and customized fixture to verify wall thickness, aperture and buckle spacing for seamless subsequent component assembly.
5. Common Molding Defects and Optimized Solutions
Warpage mostly arises from uneven cooling and insufficient packing, adjustable via optimizing cooling water flux and prolonging packing duration. Sink marks concentrate on thickened buckle positions, solvable by increasing packing pressure and modifying gate location. Silver streak and bubble mainly root in incomplete raw material drying and improper injection speed, fixed by tightening drying specification and optimizing segmented filling parameter. Excessive flash results from insufficient clamping force and oversized mold clearance, which can be improved by mold maintenance and pressure adjustment.
Conclusion
Router shell injection molding is a systematic refined production covering material preparation, molding operation and post finishing. Accurate control of temperature, pressure, speed and cycle plus high-precision mold becomes the core of stable mass production. With domestic electronic products developing toward lightweight and high appearance, continuous process upgrading steadily improves finished quality of communication plastic housings in China’s injection molding industry.
