Are there detailed steps for the second inspection of ceramic linings?

I. Pre-inspection Safety and Preparation Steps 1.Operators should wear 350℃-resistant thickened heat-insulating gloves and high-temperature-resistant goggles. Use a high-temperature insulating voltage tester to confirm that the main heating circuit of the hot runner is completely disconnected, leaving only the low-voltage power supply to the temperature measurement circuit. 2.Clean up all flammable debris such as thermal grease and plastic seals around the inspection area. Lay a high-temperature-resistant heat-insulating mat on the work surface to prevent the high-temperature nozzle from contacting the work surface and causing safety hazards. 3.Connect the pre-filtered dry compressed air source, confirming that the air source dew point is ≤-40℃ (moisture content ≤0.01%). Pre-install the customized high-temperature-resistant sealing tooling connector onto the inlet of the hot runner nozzle, manually tightening it to ensure there is no looseness. 4.Start the hot runner temperature control system, setting a linear heating rate of 50℃/h. Precisely heat the nozzle to its rated operating temperature of 320℃, and start a 2-hour heat preservation program to ensure uniform nozzle temperature and complete thermal expansion between the ceramic and H13 steel substrate. II. High-Temperature Sealing Performance Test Procedure 1.Connect a digital precision pressure gauge with an accuracy of 0.001 MPa. Slowly open the inlet valve to introduce 0.5 MPa of dry compressed air into the nozzle flow channel. After the pressure gauge reading stabilizes, close the inlet valve and begin a 30-minute pressure holding test. 2.Throughout the test, use a handheld infrared thermal imager to scan the entire outer surface of the nozzle at a uniform speed of 5 cm/s. If a cold spot with an abnormal temperature drop ≥10℃ is observed, this is a leak point. Immediately stop the test, release the remaining pressure in the flow channel, and check for gaps between the liner and the substrate. 3.After the pressure holding test is completed, verify the pressure gauge reading. If the pressure drop is ≤0.01 MPa within 30 minutes, the high-temperature sealing performance is considered qualified. Simultaneously record the ambient temperature, real-time nozzle temperature, and initial/final pressure data to create a traceable test log. 4.Slowly open the pressure relief valve to completely release the compressed air in the flow channel. Remove the inlet tooling connector and clean any residual oil from the interface with a lint-free cloth dampened with anhydrous ethanol. III. Thermal Shock Stability Cyclic Test Procedure 1. Turn off all heating modules in the hot runner. Set the temperature control system to natural cooling mode. Do not use forced cooling methods such as air cooling or water cooling. Allow the nozzle to cool slowly to room temperature in a dust-free environment at a rate ≤30℃/h. 2.After the nozzle has completely cooled to 25℃, insert a high-temperature resistant high-definition industrial endoscope through the nozzle inlet and move it along the flow channel axis to scan the entire process, recording the condition of the ceramic liner's inner wall frame by frame. Confirm that there are no dark lines, edge chipping, cracks, or misalignment defects. 3.Restart the hot runner temperature control system and heat to 300℃ at a rate of 50℃/h. Hold at this temperature for 30 minutes, then allow it to cool naturally to room temperature again, completing the second thermal shock cycle. After the cycle, re-inspect the liner's condition using the endoscope. 4.Repeat the above heating-cooling-re-inspection process, completing a total of 3 complete thermal shock cycles. Use a digital display temperature controller to automatically record the temperature change curve for each cycle, confirming that there are no sudden temperature changes. IV. Operating Condition Matching Accuracy Verification Procedure 1.After all thermal shock cycles are completed, restart the hot runner and heat to the rated operating temperature at a rate of 50℃/h. Hold at this temperature for 1 hour to allow the system to enter a stable production state. 2.Using a calibrated Husky K-type coupler probe, select 5 equidistant temperature measurement points along the nozzle flow channel axis. Measure the actual temperature of the ceramic liner area point by point, verifying the data displayed on the temperature controller. Confirm that the deviation between the measured temperature and the displayed value is ≤ ±0.3℃, with no local overheating points or temperature data jumps/drifts. 3.Remove the nozzle from the hot runner manifold plate and place it on a high-precision dial indicator support. Re-measure the coaxiality of the flow channels at both ends of the nozzle. Confirm that after high-temperature cycling, the coaxiality deviation between the liner and the substrate flow channels is still ≤ 0.02mm, with no axial displacement or deformation. 4.Gently apply a fluorescent penetrant to the mating surfaces of the liner and the substrate. After standing for 5 minutes, wipe off any residue with anhydrous ethanol. Observe under UV light to confirm that there are no fluorescent penetration traces, completely blocking the penetration path of high-concentration fluorine decomposition products. V. Final Reinstallation and Acceptance Procedures 1. Thoroughly clean the nozzle splicing surfaces and flow channel interfaces with anhydrous ethanol using a lint-free cloth to remove any residual penetrant, oil, and impurities. Apply a 0.02mm thick layer of high-temperature resistant fluorine passivation paste evenly. 2.Replace the nozzle with a new, compatible perfluoroether rubber sealing ring. Precisely align the nozzle with the regenerating flow channel manifold and tighten the fixing screws diagonally, maintaining a torque of 8 N·m to avoid localized stress compressing the ceramic liner. 3.Compile all test data, temperature profiles, and endoscopic images to create a complete second inspection and acceptance report. Archive this report in the hot runner's full lifecycle maintenance log and mark the next scheduled re-inspection date.