I.Judgement Criteria for Level 1 (Mild Lock-up)
Characteristics of Displacement: A gentle tap with a copper hammer produces noticeable micro-displacement after the hot runner cools to room temperature, without any rigid jamming sensation.
Mating Surface Condition: The inner wall of the mounting hole is free of any visible scratches or metal adhesion marks; only a minor localised frictional resistance is present.
Mould Condition: The mould plate and core exhibit no deformation or cracks; all mating clearances continue to satisfy the design specifications.
Conclusion of Judgement: The repair can be completed in 30 minutes to 1 hour without the need for additional machining; there is no substantial damage.
II. Judgement Criteria for Level 2 (Moderate Lock-up)
Displacement Characteristics: The mating interface is progressively loosening after cooling; manual pushing does not result in displacement; a loosening agent and standing for more than 2 hours are necessary.
Mating Surface Condition: The inner wall of the mounting cavity is adorned with localised interlocking scratches and metal adhesion burrs; there is no structural damage in the large area.
Condition of Mould: The mould core possesses no cracks, the mould plate exhibits no discernible deformation, and the locating ring is the sole component that exhibits a slight deviation in coaxiality.
Conclusion: The repair can be completed in 2-4 hours without the need for complex machining; it only necessitates the grinding and cleaning of the mating surfaces.
Judgement Criteria for Level Three (Severe Lock-up):
Displacement Characteristics: The hot runner component can only be removed using the thermal expansion method; conventional tapping and lubrication are utterly non-effective.
Mating Surface Condition: The inner wall of the mounting cavity exhibits extensive wear and biting, roundness that exceeds tolerances, and localised traces of cold welding adhesion.
Condition of Mould: The mould core surface has minor extrusion cracks, and the mould plate exhibits localised slight deformation, necessitating welding repair.
Conclusion: Machining repair is necessary, with repair costs ranging from several thousand yuan and a completion time of 1-3 days.
IV. Judgement Criteria for Level Four (Extreme Lock-up):
Characteristics of Displacement: The hot runner and mounting hole are completely rigidly welded together, rendering conventional unlocking methods completely ineffectual. Thus, removal is impossible.
Condition of the Mating Surface: The hot runner manifold body demonstrates compression deformation, and the mounting apertures are entirely deformed.
Condition of Mould: The core moulding components are irreversibly damaged, the mould plate parting surface fit is compromised, and the mould core is entirely cracked.
In conclusion, The core components must be custom-made, necessitating a repair process that takes 7-15 days and incurs repair costs exceeding 50,000 RMB. The mould may be rendered unusable in severe cases.
This grading method is optimally suited to the on-site conditions of precision injection moulding hot runner production lines, as it facilitates rapid and precise grading and prevents secondary mould damage that may result from mistakes.
