Frosting Around the Outlets Caused by Too Low Spinneret Face Temperature

One or several holes of the spinneret show reduced filament output or are completely blocked, with no filament extruded or only extremely fine filament extruded from the corresponding holes. Spinneret clogging reduces the number of spinning positions and decreases output; the holes around the clogged hole show output fluctuations due to flow redistribution, affecting the overall yarn bundle uniformity. When clogging is severe, the machine must be stopped to replace and clean the spinneret, and each shutdown loses several hours of output and tens of kilograms of waste yarn.

1. Mold/tooling factor: excessive cooling of the spinneret surface (air leaking onto the hot plate face). 2. Spinning temperature factor: the spinning temperature determines the melt viscosity and rheological behavior, directly affecting the spinnability, thickness uniformity and surface quality of the fiber. Excessively high temperature leads to degradation, yellowing and filament breakage, while excessively low temperature leads to poor plasticization and increased extrusion pressure; it needs to be precisely set according to the chip IV value and stably controlled.

1. Process parameter optimization and adjustment: increase thermal insulation and adjust the annular airflow to prevent cold air from directly impacting the plate and hole outlet surfaces. 2. Troubleshooting of spinning problems follows the sequence of "chips → temperature → metering → spinneret → cooling air". First check the chip dryness and IV value, then verify the temperatures of each section of the spinning box and pipeline, next verify the metering pump accuracy and pressure stability, further check the spinneret cleanliness and hole shape condition, and finally adjust the cooling air field parameters to make the wind speed and temperature evenly distributed. 3. Preventive management: establish standardized process parameter cards and quality control limits for each mold/product, and regularly conduct process capability index (CPK) evaluations. For recurring problems, use fishbone diagrams or the 5Why analysis method to trace the root cause, and solidify the countermeasures as PFMEA control points. Establish a regular equipment maintenance system, and implement life management for key tooling such as dies/spinnerets/calender rolls/coating heads.

The essence of spinneret clogging is that impurity particles or degraded gel in the melt clog the tiny spinneret hole inlets. The core of the solution is "cleanliness + filtration + regular cleaning": strengthen chip purity control to reduce impurity sources, use pre-filters (sintered metal filters, sand layers) to intercept gel particles, and regularly clean the spinneret with the triethylene glycol ultrasonic method.