Injection Mold Inspection and Acceptance Standards

Injection molds are the core equipment for plastic injection production, and their quality directly determines product precision, appearance, production stability, and service life. Currently, the industry follows the national standard GB/T 12554-2006 "Technical Conditions for Plastic Injection Molds" as the basis, combined with precision manufacturing and automated production requirements, forming a complete and operable acceptance system. A qualified mold must meet standards in all links from documentation to safety delivery before mass production. This article details the core acceptance points with accurate data for on-site application.

Pre-Acceptance of Documentation

Documentation is the foundation of mold acceptance, ensuring traceability and maintainability. Key documents to verify include complete 2D/3D drawings, BOM lists, material certificates, heat treatment and hardness reports, trial molding records, maintenance manuals, wearing parts lists, and certificates of conformity. All documents must match the actual mold, with clear markings of key dimensions, materials, and heat treatment requirements. For important parts, spectrum analysis can be used to confirm material composition, and all documents must be properly signed and sealed to ensure validity. Incomplete or inconsistent documents will delay acceptance until rectified.

Appearance and Structure Inspection

Appearance and structure reflect processing and assembly quality. The mold surface must be free of rust, bumps, and unauthorized welding, with uniform template chamfers (≥1.5mm). The parting surface must be flat and clean, with a clamping gap ≤0.02mm and no misalignment. Cavity, core, and insert surfaces must be smooth: ordinary surfaces Ra ≤0.8μm, mirror surfaces Ra ≤0.2μm, without scratches or galling. Guide pillars, guide sleeves, sliders, lifters, and ejection systems must move smoothly without jamming or interference. Sliders must retain ≥2/3 of their length in the chute after core pulling. Clear markings for mold number, waterways, and oil/gas ports are required for easy operation.

Material and Hardness Acceptance

Materials and hardness determine mold life. The mold base must meet GB/T 12556 standards. Molding parts (cavities, cores) use qualified steels such as P20, 718H, S136, or NAK80; corrosion-resistant/mirror molds use 420-series stainless steel. Hardness requirements: cavities/cores HRC 48-54, guide pillars/ejector pins ≥HRC 60, sliders/lifters ≥HRC 35. Slider pressure plates and wear-resistant plates require nitriding (≥HV 700). Key parts can be spot-checked for hardness, and material reports must match the actual steel to avoid downgrading.

Assembly Precision Acceptance

Assembly precision ensures product stability. Guide pillar-guide sleeve fit clearance is 0.01-0.03mm; slider-chute clearance 0.01-0.02mm. The ejection system must be balanced, with ejector pins flush or slightly recessed (0-0.1mm) to avoid product marks. Standard positioning rings (φ100/φ150) must fit the injection machine accurately. Inserts and pins must be tightly fitted to prevent flash. High-strength screws are used for force-bearing parts with reliable anti-loosening structures.

Cooling, Venting and Control System Acceptance

Cooling and venting affect production efficiency and product quality. Cooling waterways must be unobstructed, leak-proof, and evenly distributed, with clear inlet/outlet markings. Hot runners require accurate temperature control without glue leakage. Venting grooves (0.015-0.02mm deep) are set at filling ends, weld lines, and dead corners to avoid air trapping. Hydraulic, pneumatic, and electrical systems must function stably, with effective safety circuits and emergency stops.

Trial Molding and Product Acceptance

Trial molding verifies mold performance. Process parameters (temperature, pressure, speed) must be stable, with a qualified molding cycle. Continuous trial of 30-50 molds must produce defect-free products (no short shots, sink marks, or burn marks). Key dimensions meet drawings and GB/T 14486, with CPK ≥1.33. Wall thickness tolerance is ±0.1mm, and assembly fits well. Continuous 8-hour production ensures mold stability without sticking or leakage, and product functional tests (strength, drop) must pass.

Safety and Delivery Acceptance

Hoisting holes and rings must be safe and strong for stable lifting. Exposed moving parts and electrical/hydraulic systems meet safety standards. The mold is cleaned, rust-proofed, and well-packaged for transportation, with blocked water/air/oil ports. All documents, spare parts, and wearing parts are delivered together for immediate mass production.

In summary, mold acceptance is a full-process verification. Strictly implementing each standard ensures stable, efficient, and low-fault production.