I. Method of Visual Inspection and Weight Verification
Short-Shot Test Method: Directly compare the filling length of each cavity, terminate the injection stroke early, and remove the partially filled semi-finished product. Uniformity is indicated by a filling length deviation of ≤2% across all cavities.
Method for Weighing Product Weight: Weigh each cavity individually after randomly sampling 20 mould products. Determine the coefficient of variation (CV). The filling uniformity satisfies the standard when the CV is less than 1.3%.
Appearance Defect Inspection Method: Visually examine all cavity products. The filling is essentially uniform, as evidenced by the absence of defects such as flash, shrinkage marks, burning, or absent material.
II. Quantitative Evaluation Method for Mould Cavity Pressure:
Evaluation of Filling Time Difference: Utilise the mould cavity pressure curve to determine the time difference Δt between the filling stages of each cavity. Acceptable filling uniformity is indicated by Δt ≤0.01~0.03s for small precision products and Δt ≤0.05~0.2s for large products.
Peak Pressure Difference Assessment: Determine the peak pressure difference between the filling and holding phases of each cavity. Satisfactory filling uniformity is indicated by a pressure difference value of (Max-Min)/Max < 5-7%.
III. Methodology for Property and Dimensional Verification:
Key Dimension Consistency Verification: Utilise a coordinate measuring machine to evaluate the key assembly dimensions of all cavity products. Stable filling uniformity is indicated by dimensional deviations that are maintained within one-third of the product tolerance zone.
Mechanical Property Sampling Test: Each cavity product undergoes sampling tests to determine its impact and tensile strength. The filling uniformity completely satisfies precision manufacturing requirements when mechanical property fluctuations are ≤ 5%.
IV. Method of Digital Long-Term Monitoring
Pressure curves are collected in real time throughout the entire production cycle by utilising in-mold pressure sensors that are installed in each cavity. The pressure curves' overlap for all cavities is ≥ 95%, which suggests that there is no drift in the uniformity of long-term filling.
Real-time statistics of weight and dimensional data for each batch of cavity products are generated through the integration with the MES system. This process automatically generates filling uniformity trend reports and provides early cautions of filling imbalance risks.
This judgement method is optimally suited for the precision hot runner multi-cavity mould injection production line that you are currently operating. It is capable of rapidly and precisely assessing the uniformity of filling and preventing the discharge of batches of defective products.
