Screw slipping

The screw cannot feed and plasticize normally when retreating. When this defect occurs in products of Process No. 1, it is usually related to a specific process parameter range or equipment status. If it persists, it will directly affect the product qualification rate and production cycle, increasing material loss and rework costs. Timely diagnosis and elimination is a basic requirement to ensure stable production.

1. Equipment factor: The temperature at the rear section of the barrel is too high, causing the material to melt and adhere in advance; the material lubricity is too strong; the screw feeding section design is improper; the hopper discharge port is blocked. 2. Mold comprehensive factor: In addition to venting, mold design parameters such as the cooling water circuit layout, gate position and size, and draft angle all have a systematic impact on product quality, and optimization is needed from the source of mold design.

1. Process parameter optimization and adjustment: Reduce the temperature at the rear section of the barrel, check the smoothness of the discharge port, and replace the screw with a reasonably designed feeding section. 2. Systematic troubleshooting method: Troubleshoot item by item in the order of "parameters -> materials -> mold -> equipment". First adjust the parameters that are easiest to change, such as injection pressure and temperature, and observe the effect; if there is no improvement, check the drying and flowability of the raw material; further check the mold venting and gate design; finally check the mechanical state of the equipment (non-return ring, screw). Change only one variable at a time to determine the root cause. 3. Preventive management: Establish standardized process parameter cards and quality control limits for each mold/product, and regularly conduct process capability index (CPK) assessments. For recurring problems, use fishbone diagrams or 5Why analysis to trace the root cause, and solidify countermeasures as PFMEA control points.

This problem is a typical manifestation of screw slipping in '2079851475616104452, and the core of the solution lies in eliminating the root cause of the defect through systematic optimization of process parameters (temperature, pressure, speed) and rationality checks of mold design. It is recommended to start with process parameter adjustment and gradually go deeper to the equipment and mold levels.