How to Determine if Stress in a Hot Runner System is Completely Eliminated

Our experience in hot runner thermal shock fracture repair and stress reduction allows us to confirm with certainty that all stress has been relieved in a hot runner system with a multi-dimensional approach:

I. Appearance and Process Inspection

Process Record Verification: Verify that the stress-relief annealing temperature, holding time, heating/cooling rates fully conform to the established specifications, and there is no missing or deviating process parameters.

Visual Check for Deformation: Visually check for any obvious deformation or warpage of the hot runner plate and mounting holes and verify that the datum flatness fulfills factory tolerance requirements.

II. Instrument Testing by Professionals

Residual Stress Analyzer Testing: Random inspection of the repaired weld region and temperature stress concentration locations are performed using an X-ray residual stress analyzer to check that the residual stress value has lowered to a safe range, which is within 10% of the material's yield strength.

Pink penetrant test re-inspection - Perform penetrant test on the repaired weld area, to make sure that there are no delayed-development microcracks present, implicitly confirming that the stress has been entirely released.

III. Simulation of Operating Condition Verification

Heating Test: Hot and cold cycle a full cycle according to the actual production temperature curve of the hot runner. Then cool down and reinspect . No new cracks or dimensional deviations = all stresses removed .

Through this multi-layered testing, the hot runner stress elimination effect can be 100% confirmed and the cracking may be avoided from recurring in the subsequent use.