I. Fundamental Rapid Diagnostic Techniques
Phenomenon Comparison Method: Rapidly eliminate other types of lockdown faults by directly matching typical fault characteristics.
Temperature Retrospection Method: To verify the presence of overheating or abnormal heating rates, retrieve the historical temperature rise curves of the hot runner temperature control system.
Gap Verification Method: In a cold state, utilise a feeler gauge to rapidly assess the mating clearance of the mounting apertures to ascertain whether there are any clearance deficiencies.
Manually endeavour to push the hot runner manifold to confirm whether there is a complete jamming on one side or no displacement margin. Method of Displacement Verification.
II. Standardised On-Site Diagnostic Procedures
Step 1: Safety Pre-Confirmation
Disconnect all heating power to the heated runner and allow it to cool naturally to below 100℃. To continue with subsequent operations, it is necessary to wear gloves that are resistant to heat.
Record the current fault phenomena, including the time of lockup, the operating temperature of the hot runner at that time, the presence of any accompanying abnormal noises, and the presence of anomalous deformation in the mould.
Step 2: Discontinue Non-Thermal Expansion-Related Locking
In order to exclude bolt failure-induced locking, inspect the hot runner bolts for breakage or stripping.
In order to exclude plastic melt solidification-induced locking, inspect the heated nozzles for leakage or cold material clumping.
In order to prevent the misalignment of mounting apertures, which can result in jamming, inspect the mould parting surface for foreign objects.
Step 3: Assess the Thermal Expansion Locking Characteristics
Confirm whether the hot runner heating rate exceeds 50℃/30min and whether there is any overheating by retrieving historical data from the temperature control system.
Gently tap the hot runner manifold platen with a copper rod to verify that there is no displacement during the tapping process, which indicates complete rigid locking.
The clearance between the hot runner platen and the upper mould plate should be verified using a feeler gauge to ensure that it is significantly less than the designated safety value of 0.5mm.
Step 4: Rapid Evaluation of Damage Levels
In order to ascertain whether there is moderate to severe mould damage, examine the mould platen around the mounting holes for visible deformation or fractures. Confirm whether the jamming is only localised and slight or entirely rigidly locked around the entire circumference by slightly rotating the hot runner component.
Document the location of the lock-up: Is it a uniform lock-up that extends around the entire circumference, or is it a localised jam on one side? This will serve as the foundation for subsequent repair strategies.
Step 5: Rapid Identification of the Root Cause
Confirm whether there are any issues with insufficient clearance calculations during the design phase by reviewing the design clearances in the drawings.
Verify the coaxiality of the positioning ring to determine whether there are any issues with off-center loading that could result in clogging as a result of machining deviations.
Confirm whether the installation records indicate any issues with bolts being tightened on one side only or whether standard procedures were not adhered to.
This comprehensive diagnostic process can identify the fault within 15 minutes, accurately distinguishing between thermal expansion lock-up and other forms of lock-up faults, and preventing secondary mould damage caused by misoperation.
