How to Inspect the Drying Status of Hot Runners After Drying

I. Simple Rapid Testing Techniques

Insulation Resistance Retest Procedure

Operation. Test insulation resistance between heating element, thermocouple core wire and hot runner housing channel by channel using a 500V digital megohmmeter.

Pass/Fail Criteria: Two consecutive retests 30 minutes apart. The insulation resistance is ≥20MΩ and without a downward trend, it means that the moisture is totally eliminated.

Time Needed: The entire channel test takes 5-10 minutes and is the most important and quickest test.

Verification Procedure for Heating Curve

Operation: Turn on the hot runner, and heat it from room temperature to 160℃ at a normal rate, monitoring the temperature changes during the procedure.

Pass/Fail Criterion: No long temperature platform around 100℃ throughout the heating process, and the deviation of the heating rate from the standard curve of the same model of dried hot runner is less than or equal to 10%.

Time Needed: Completed in 30 minutes, enabling for the detection of hidden moisture trapped in deep cracks.

 

II. Additional authentication options

method of verifying the condition of a surface

Operation: Open the hot runner junction box and examine the internal terminals, insulation layer and exposed metal surface.

Pass/Fail Decision All parts are entirely dry, with no water mist or condensation markings, and the terminals are free of oxidation or discoloration.

Time Estimate: 2-3 minutes to complete thorough appearance verification.

High-Temperature Insulation Re-verification Process

Operation: Heat the hot runner to 160℃ and hold for 30 minutes, then remeasure the insulation resistance under high temperature condition.

Judgment Pass/Fail Insulation resistance ≥ 0.5MΩ at high temperature, and insulation resistance does not decrease rapidly with increase of temperature.

Time Required: Completed within 40 minutes, preventing insulation breakdown owing to moisture condensation at high temperatures after passing at room temperature.

 

III. Priority rules for quick judgments

First use the insulation resistance re-test method for the initial judgment, then combine with the temperature rise curve verification method to accomplish the full-dimensional confirmation within 30 minutes. This allows a full drying without significant waiting times, and a quick entry into the installation phase.