Automotive injection-molded components cover interior and exterior decorative parts, structural functional fittings and electronic housing accessories, whose finished quality affects vehicle assembly precision, driving safety and long-term environmental durability. Subject to IATF16949 quality management system, production is controlled from raw material incoming inspection, in-process molding, regular mold maintenance, semi-finished testing to finished product storage, preventing shrinkage, warpage, dimensional out-of-tolerance and low-temperature cracking defects caused by irregular operation. Standardized whole-process control helps manufacturers satisfy strict incoming inspection rules from vehicle OEMs and cut after-sales compensation losses from defective delivery.
1. Incoming Acceptance Control of Raw MaterialsAll modified plastic, glass-filled resin and elastic auxiliary materials must provide factory COA, RoHS certification and automotive material qualification documents, with sampling tests on melt index, moisture content and filler proportion before warehousing. Hydroscopic materials like PA and PC follow fixed drying parameters to limit final moisture within specified threshold. Appearance-oriented automotive parts forbid recycled sprue blending, while structural components restrict recycled scrap proportion under 8%. Different material grades are stored in separated sealed zones with complete batch labeling to realize full traceability and avoid wrong material mixing.
2. Process Parameter Locking and In-process Molding Supervision
Key parameters including barrel temperature, mold temperature, injection pressure and backpressure are locked after first-article approval; any parameter modification needs formal application and repeated first-piece inspection before resuming production. Barrel segmented temperature is set based on material property to avoid thermal decomposition leading to brittle finished products; mold temperature is controlled within ±2℃ fluctuation for thin-wall appearance pieces to balance shrinkage uniformity and reduce warpage. Field operators conduct parameter check every two hours during continuous production and stop machine immediately once abnormal batch defects emerge. Specialized speed adjustment is implemented for glass-reinforced material to lower fiber exposure and surface whitening issues.
3. Daily, Weekly and Monthly Mold Maintenance RegulationsAutomotive component molds mainly adopt 718HH, S136 and SKD61 steel with tiered maintenance schedule. Daily post-production cleaning removes cavity dust and residual plastic residue with silicon-free release agent only; weekly inspection checks guide pin, hot runner and cooling channel for blockage and loose inserts; monthly maintenance contains local polishing and nitriding recheck for easily worn rib and buckle inserts. Full disassembly maintenance is required every 50,000 shots to discover early cavity collapse and abrasion risks, stabilizing long-term dimensional consistency of molded parts. All repaired molds pass trial run validation before formal mass resumption.
4. Graded Appearance and Dimensional Inspection Specifications
Inspection work is divided into first-article check, periodic patrol inspection and last-piece confirmation. First-piece test covers full dimensional measurement, appearance screening and assembly matching verification before batch production start. Appearance surfaces are classified into A/B/C three grades: A-grade visible vehicle surface prohibits scratch, sink mark and obvious weld line; B-grade hidden assembling surface allows tiny inconspicuous flaws; C-grade internal structural part relaxes non-functional appearance requirements. Key fitting dimensions are sampled with caliper and CMM, and unqualified products are marked and isolated separately. Parts for subsequent painting and ultrasonic welding add extra adhesion and welding strength sampling test.
5. Post-processing, Warehouse and Delivery Management StandardsPC and PA automotive pieces needing stress relief go through constant-temperature annealing to eliminate internal stress and prevent low-temperature cracking after vehicle assembly. Deburring operation uses dedicated cutting tools to avoid accidental surface scratch. Qualified finished products are stored inside anti-static turnover boxes under constant-temperature warehouse environment to stop extrusion deformation and aging distortion. Pre-delivery final inspection verifies product specification, appearance and batch information with complete inspection report attached for shipment, complying with OEM full-trackable delivery requirements.
