Specifications for Electronic & Electrical Injection Molding in China’s Injection Manufacturing
As foundational components for finished electronic and electrical equipment, injection-molded plastic parts cover connector housings, power supply casings, internal structural fittings for household appliances and industrial control components. Subject to stringent requirements for assembly tolerance, electrical insulation, heat resistance, flame retardancy and environmental compliance, the full-set technical specifications for electronic injection molding run through raw material inspection, mold fabrication, molding parameter setting, post-processing and finished product testing. With continuously tightened global RoHS, halogen-free and UL safety standards across China’s injection manufacturing industry, in-depth interpretation of standardized processing codes becomes an essential prerequisite for molding enterprises to stabilize product quality, pass downstream supplier qualification audit and cut production rejection cost. Improper execution of process specifications will trigger common defects including poor dimensional consistency, insulation performance degradation, burnt marks and environmental non-compliance, which may lead to whole batch rejection by electrical appliance clients.
1. Raw Material Receiving and Batching Control Specifications
Major feedstock for electronic plastic parts consists of ABS, PC, PC/ABS alloy, flame-retardant modified PP, reinforced PBT and PA66, all of which need to satisfy UL flame resistance certification and international eco-friendly regulations before incoming warehousing. All incoming batches must be attached with official material certification and third-party inspection reports; uncertified off-grade plastic and miscellaneous recycled scraps are prohibited from direct production mixing. Environmentally restricted materials for halogen-free or RoHS-compliant products require independent warehouse zoning to avoid cross-contamination with ordinary non-compliant resins. Hygroscopic engineering plastics such as PC, PA66 and PBT demand standardized pre-drying procedures: PC is dried at 110~120℃ for 3 to 4 hours while PA66 is baked at 80~90℃ for 4 hours to limit residual moisture below 0.2%, effectively eliminating silver streaks, internal voids and compromised insulating property caused by excessive water content inside pellets.
Color masterbatch, flame retardant additives and glass fiber fillers must conform to harmful substance limit standards during compounding, and halogen-containing flame retardants are forbidden for low-halogen electronic projects. Batching workshops implement dustproof isolation to stop foreign particulate impurities from generating black spots and contact failure on finished plastic pieces. The reuse of sprue and runner scrap follows fixed mixing proportion rules: recycled material blending ratio is controlled under 20% for non-appearance functional parts, and high-precision insulating structural components ban recycled feedstock entirely to prevent unstable mechanical and electrical performance.
2. Design and Manufacturing Specifications for Production Molds
Electronic components feature thin-wall geometry, dense snap-fit structures, precision jack holes and tiny terminal pillars, so core mold specifications focus on dimensional precision, proper vent layout and uniform cooling channel design. Dimensional tolerance of finished cavity is set at ±0.02~±0.05mm consistent with domestic electronic industry benchmark; split insert construction is adopted for fine pin positions to facilitate post-mold maintenance and modification. Side gate or submarine gate is prioritized over tiny pinpoint gate to prevent high shear-induced material carbonization near precision terminals.
Venting slots with 0.01~0.02mm depth are arranged intensively at weld lines and terminal filling ends, as trapped air inside mold cavity easily triggers plastic scorching and permanent insulation failure. Cooling pipelines are arranged closely surrounding molding cavity to balance mold surface temperature and avoid uneven shrinkage resulting in distorted snaps and offset aperture positions. Mold steel grade is selected according to annual production volume: S136 and NAK80 pre-hardened mold steel are applied for mass-production precision molds with mirror cavity polishing to minimize burr and demolding scratch. Every newly finished mold completes trial production with reserved standard samples as dimensional benchmark for subsequent batch production inspection.
3. Standardized Execution of Injection Molding Process
All molding parameters are defined based on inherent material property and component precision requirement, arbitrary overheating or over-pressure setup is prohibited to avoid irreversible thermal decomposition of flame retardant ingredients and weakened electrical insulation of finished parts. Melt temperature of PC and glass-filled polyamides is restricted within recommended range; excessive barrel heat causes breakdown of flame retardant additives and invalidation of safety certification. Injection and packing pressure are set at the minimum feasible value to achieve complete cavity filling, since redundant high pressure generates fine flash debris which may fall off and cause short-circuit risk inside electronic assemblies.
Precise mold temperature control directly governs dimensional stability: PC products run at 60~80℃ mold temperature while glass-reinforced materials require 70~90℃ cavity temperature to narrow shrinkage fluctuation of assembly holes and buckle structures. Forming cycle is optimized reasonably to balance sufficient cooling and idle energy waste. Complete purging procedure is mandatory during material or color switching; resins with different flame retardant or eco grades cannot share same injection barrel to prevent cross mixing leading to failed regulatory test.
4. Post-Processing, Warehousing and Finished-Part Inspection Rules
Deburring operation avoids forced scraping which cracks snaps and deforms precision holes; cryogenic deflashing or customized cutting fixture replaces manual rough trimming for terminal-hole components. Terminal pressing procedure fixes uniform compression load to stop shell cracking or loose embedded metal terminals. Three-stage inspection system including first-piece check, in-process patrol inspection and final batch inspection is implemented on-site: formal mass production starts only after first article passes dimension, appearance and flame resistance testing, and patrol inspection focuses on dimensional tolerance, flash, incomplete filling and deformation issues.
Eco-compliant products are packed with halogen-free neutral plastic bags separately; warehouse maintains stable ambient temperature and humidity to prevent hygroscopic plastic parts from absorbing moisture and deteriorating electrical performance. Non-conforming goods are stored in marked independent area classified by defect origin, never blended with qualified finished products for downstream electronic assembly.
Conclusion
Technical specifications for electronic appliance injection molding center on environmental compliance, electrical safety and precision assembly to build full-process control covering raw material management, mold development, molding execution and finished goods inspection. Qualified raw material management ensures compliance with global eco and flame retardant codes, precise mold design lays dimensional foundation for assembled plastic parts, standardized molding parameters cut forming defects, and layered inspection blocks defective outflow to downstream clients. Chinese injection manufacturers can reduce customer rejection rate and production scrap loss by fully complying with above specification system, maximizing material performance and satisfying supporting demands across consumer electronics, industrial control equipment and small home appliance sectors.
