The standard process of melt pump repair can be summarized into the following four core steps, which are summarized as follows in combination with professional maintenance guidelines and factory practice:
Step 1: Disassembly and Record
When disassembling the old pump, you need to record the position, direction and assembly sequence of the parts throughout the whole process to avoid misplacement of the reassembly. Use soft mouth vise to fix the pump body to prevent collision damage, focusing on labeling the relative position of gears, bushings, seals and other key parts.
Step 2: High-temperature glue removal and deep cleaning
Adopt high-temperature calcination carbonization treatment for the residual melt (usually control the temperature to avoid material performance degradation), and then completely remove the carbonization residue by physical or chemical means. Need to ensure that the gear meshing surface, bearing seat and other hidden parts of no gel residue, otherwise affect the subsequent assembly precision.
Step 3: Component Inspection and Replacement
Precision Mapping: Measure key dimensions such as gear shaft diameter, end cap clearance, shell cylindricity, etc., and compare with original parameters to determine the degree of wear;
Targeted Replacement: Gear/shaft sleeve wear exceeds the poor (a common source of failure), seals aging or bolt deformation need to be replaced; seriously damaged parts such as cracks in the hydraulic chamber need to be returned to the factory for repair;
Reinforcement treatment (optional): spray tungsten carbide and other wear-resistant coatings on the gear surface to extend the life.
Step 4: Precision assembly and debugging
Pre-lubrication: apply high temperature grease to the threaded parts, and tighten the bolts in diagonal order in stages to prevent leakage from partial load;
Dynamic test: manually rotate the spindle to confirm no jamming, focusing on testing the clearance of the shaft seal gland (standard value 0.1-0.3mm);
Pressure verification: gradually pressurize after no-load operation, monitor the stability of the outlet pressure, abnormal fluctuations need to re-adjust the gap.
Supplementary note: fault correlation in repair
If pressure fluctuation or leakage occurs after repair, it is mostly caused by assembly clearance deviation (e.g. gear side clearance > 0.08mm) or improper seal installation, which needs to be returned for repair and adjustment; abnormal temperature rise needs to be checked for bearing preload and cooling system.
Tips: The overhaul cycle is usually 24-36 months, and minor repairs (seal adjustment/lubrication maintenance) should be carried out every 3-6 months to prevent sudden failures.
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