Inspection Items for Injection Mold Delivery Acceptance
Injection mold delivery acceptance serves as a core quality inspection procedure before mold shipment and on-mass production, which directly determines mold machining precision, opening and closing stability, service life and finished product yield. Mold acceptance cannot be judged merely by the appearance of trial samples. Comprehensive systematic verification should be carried out covering mold mechanical structure, precision fitting, water circuit system, moving mechanism, gating and venting, trial molding quality, spare parts and technical documents. Most defects such as flash, scratch, deformation, water leakage, mold jamming and precision deviation occurring during mass production stem from loose acceptance standards and undetected hidden flaws. To ensure stable mass production right after mold setup, this paper sorts out all inspection items for standardized delivery acceptance of injection molds.
1. Mold Overall Appearance and Basic Structure Acceptance
After mold arrival, inspect overall appearance and basic structure first. Verify mold specifications, mold thickness, positioning holes and machine matching dimensions against design requirements to guarantee compatibility with the designated injection molding machine. Check that plates, mold inserts, inserts and pressure plates have no chipping, deformation, rust or severe grinding marks. The mold surface is clean without iron scraps, oil stains and processing residues. Mold nameplate, serial number and datum corner marks are clear and standard. Lifting ring holes are complete with balanced stress to meet safe hoisting and transportation demands. All fixing screws, lock blocks and pressure blocks are fully assembled and tightly locked without thread slipping, loose locking or inconsistent lengths. Mold plates open and close smoothly with no stuttering, friction noise or unilateral mold rubbing. The overall assembly structure is complete without misassembly, missing parts or dislocation.
2. Guide and Positioning System Precision Acceptance
The guiding and positioning system is the core guarantee of mold precision, controlling front and rear mold alignment accuracy, product wall thickness uniformity and sealing stability. The inspection focuses on the fitting clearance of guide posts and guide bushes. Sliding during mold opening and closing is smooth without looseness, jamming, partial wear or shaking. The parallelism and perpendicularity of guide posts meet standards with no positional offset after long-term operation. Mold positioning shoulders, taper positioning, tongue-and-groove alignment and four-sided auxiliary positioning structures fit tightly with no gaps, dislocation or edge collapse, preventing mold misalignment and mold expansion under high injection pressure. All wear-resistant positioning blocks are firmly installed with flat surfaces free of scratches and grooves, maintaining stable fitting clearance and mold precision during mass production.
3. Parting Surface Sealing and Venting System Acceptance
Parting surfaces and sealing zones are critical for controlling flash, trapped gas and burning defects. Inspect the entire parting surface for tight and flat fitting, free of depressions, steps, local gaps and grinding damage. Sealing areas are evenly lapped with standard sealing bandwidth and no missing or virtual sealing positions. Complete vent grooves are set at melt flow ends, weld line convergence positions, deep rib dead corners and around holes. Vent depth strictly matches plastic materials to avoid trapped gas and flash. Vent grooves stay clean without blockage and iron scraps. Runner overflow and storage grooves are reasonably arranged to improve weld lines, trapped gas and burning defects, satisfying venting requirements for high-speed injection molding.
4. Cooling Water Circuit System Acceptance
Water circuit system acceptance affects product deformation control, dimensional stability and production cycle. Check all water holes for completeness, intact connectors and unified specifications. Water channels are evenly arranged following cavity contours, fully covering cavities, cores, ribs and boss thick glue areas without cooling dead zones. Conduct water pressure holding test, ensuring no seepage, leakage or pressure drop. Inner walls of water channels have no severe rust and residual iron scraps. Water inlet and outlet marks are clear with definite directions for temperature adjustment and routine maintenance. Confirm water channels do not interfere with ejector pins, angle lifters and slides for convenient disassembly and maintenance to achieve balanced cooling in continuous mass production.
5. Ejection System Structure Acceptance
Ejection system acceptance ensures smooth demolding and prevents whitening, cracking, deformation and scratches on products. Inspect ejector pins, flat ejectors, ejector blocks and push plates for flat assembly with standard height difference and sufficient ejection stroke. Ejection and return movement run smoothly without jamming, locking or abnormal noise. Ejector pin clearance is reasonable, avoiding product scratching from stuck material or flash caused by excessive gaps. Ejector springs are uniformly distributed with consistent elasticity, no fracture or fatigue deformation. Limit posts and ejection limit structures are intact to prevent mold collision from over-travel. For thin-wall and precision plastic molds, ejection force uniformity is verified to avoid concentrated force at single points and guarantee stable demolding in high-speed production.
6. Slide and Angle Lifter Core-pulling Mechanism Acceptance
For complex molds with undercuts, core-pulling moving mechanisms require strict acceptance. Slides and angle lifters slide smoothly and position accurately without shaking, jamming or wear noise. Wear-resistant blocks, pressure strips, limit structures and stroke buffers are fully assembled and firmly fixed with standard fitting clearance. No displacement, offset or trapped flash occurs during mold opening and closing. The angle and stroke of angle lifters match product undercut demolding requirements with no structural interference, glue scraping or cracking risks. Slide sealing surfaces fit tightly with effective water stopping structure to prevent material accumulation, carbon deposit and water seepage. Lubrication grooves of all moving mechanisms are complete with qualified wear resistance for high-cycle automated mass production.
7. Gating System Molding Acceptance
Check sprue, runner and gate for smooth machining without tool marks, steps, burrs and processing residues. Runner corners adopt smooth transition to ensure melt flows smoothly without stagnant dead zones. Gate size, thickness, position and quantity comply with design standards for balanced filling to avoid short shot, gas marks and uneven filling. For multi-cavity molds, runner balance is inspected to achieve consistent filling among cavities without cavity difference defects. For hot runner molds, verify accurate hot nozzle alignment, intact circuits, uniform heating and hidden risks of glue leakage and accumulation to meet precision molding requirements.
8. Trial Sample Quality and Dimensional Acceptance
After mold structure acceptance, judge molding quality with trial samples. Sampled products have no short shot, burning, gas mark, sink mark, warpage, flash, scratch or weld line defects, and the surface finish of class A appearance surfaces reaches standards. Precision dimensions, assembly holes, wall thickness, concentricity, flatness and fitting clearance all meet drawing tolerances. Threads, sealing surfaces and key assembly positions are fully molded without defects. Compare appearance and dimensions cavity by cavity for multi-cavity molds. Uniform cavity difference and good product consistency satisfy mass assembly and application requirements.
9. Mold Spare Parts and Delivery Document Acceptance
Check completeness of mold spare parts, wearing parts, connectors, limit blocks, spare inserts and ejector pins. Meanwhile verify the integrity of delivered technical materials, including mold assembly drawings, part drawings, water circuit drawings, trial molding inspection reports, dimensional test records and mold maintenance manuals. Documents are clearly marked and completely filed, providing full technical support for later mold modification, repair, process debugging and daily maintenance. In summary, injection mold delivery acceptance must adopt comprehensive and refined inspection standards. Check layer by layer from structural precision, movement stability, molding performance to spare parts and documents to eliminate hidden mold defects in advance. Ensure delivered molds have qualified precision, stable operation and are ready for on-machine mass production, reducing later mold repair costs and production defect rates.
