I.Safety Preparation for Pre-treatment
Tools List: Copper hammer, copper rod, high-temperature penetrating loosening agent, air gun, local heating gun, special hot runner removal tool, feeler gauge, and heat-resistant gloves.
Safety Advice: It is imperative to refrain from striking the hot runner components directly with a hammer. You should never pour frigid water directly onto the hot mould core in order to prevent the mould core from suddenly cooling and cracking, which would render it unusable.
Confirmation of Pre-treatment: To prevent burns, ensure that the heated runner's current temperature is ≤100℃ and disconnect all heating power.
II. Initial Stage: Natural Cooling and Loosening (Prioritised, no danger of secondary damage)
Deactivate all heating modules in the hot runner, activate the mould cooling system, and permit the entire hot runner to chill naturally to room temperature (approximately 25℃) for 15-20 minutes.
Use a copper rod to press against the non-sealed surface of the heated runner manifold while wearing heat-resistant gloves. Gently tap the locked area 3-5 times with a copper hammer in the opposite direction of thermal expansion to induce a slight displacement.
Check for any movable clearance by inserting a feeler gauge into the mounting hole gap. Use a specialised tool to gradually extract the hot runner component if the clearance is ≥0.1mm.
III. Second Stage: Penetration Lubrication and Unlocking (For minor localised blockage)
In the engagement gap between the mounting hole and the heated runner, gradually inject a high-temperature penetrating loosening agent to ensure complete penetration into the thread/mating surface gap.
Allow the loosening agent to completely dissolve the metal oxide layer that was formed under high temperature by allowing it to remain for 2-3 hours.
Once more, employ a copper rod and a copper hammer to alternately tap around the hot runner in a circumferential direction, thereby gradually loosening the engagement interface. To prevent the application of excessive force in any particular area, ensure that each stroke is executed with consistent pressure.
Use a pulling tool to apply force outwards at a uniform speed, gently pulling the hot runner out of the mounting hole once the component can rotate slightly.
IV. Third Stage: Thermal Expansion Unlocking (For Severe Lock-up Scenarios)
Cover the hot runner body entirely with a heat-insulating baffle, leaving only the template area surrounding the locked mounting holes exposed.
Utilise the expansion discrepancy between the two to rapidly establish a mating gap of 0.05-0.1mm.
A staged heating operation was implemented following the reassembly, during which the temperature was elevated by 50°C every 30 minutes. The hot runner displacement was monitored throughout the process to ensure that no new jamming occurred.
