I. Insulation Resistance Retest Method
Operation: Use a 500V digital megohmmeter to test the insulation resistance between all heating elements, thermocouple cores, and the hot runner housing.
Pass/Fail Criteria: Retest twice consecutively at 30-minute intervals. A stable insulation resistance ≥20MΩ with no significant drop indicates complete moisture removal.
Testing Time: The entire channel test can be completed in 5-10 minutes, making it the fastest and most effective method.
II. Heating Curve Verification Method
Operation: Power on the hot runner and heat it from room temperature to 160℃ at a normal rate, recording temperature changes throughout.
Pass/Fail Criteria: No prolonged temperature plateau near 100℃ during heating; the heating rate deviates from the standard curve of a brand-new, dry hot runner of the same model by ≤10%; and there is no significant absorption of latent heat of vaporization.
Testing Time: Verification can be completed within 30 minutes, effectively detecting hidden moisture in deep crevices.
III. Surface Condition Verification Method
Operation Method: Open the hot runner junction box and observe the condition of the internal terminals, insulation layer, and exposed metal surfaces.
Pass/Fail Criteria: All parts are completely dry, with no water mist, condensation, or moisture buildup; terminals show no oxidation or discoloration.
Testing Time: A full visual verification can be completed in 2-3 minutes, serving as a supplementary rapid judgment method.
IV. High-Temperature Insulation Re-verification Method
Operation Method: After heating the hot runner to 160℃ and holding for 30 minutes, re-measure the insulation resistance under high-temperature conditions.
Pass/Fail Criteria: High-temperature insulation resistance ≥ 0.5MΩ; no rapid drop in insulation resistance with increasing temperature indicates no residual moisture inside the insulation layer.
Testing Time: Completed within 40 minutes, avoiding the potential for insulation breakdown due to moisture condensation at high temperatures after passing at room temperature.
V. Rapid Priority Determination Rules
Prioritize the insulation resistance retest method, which can complete the initial assessment in 5 minutes. If the insulation resistance is stable and meets the standard, it can be directly determined that the material is basically dry.
Combined with the temperature rise curve verification method, a full-dimensional confirmation can be completed within 30 minutes. Thorough drying can be confirmed without a long waiting period, allowing direct entry into the installation phase.
