Flow Mark

Ripple-like marks centered on the gate appear on the surface of the part. Flow marks spread outward from the gate as concentric circles or wavy ring patterns, similar to water surface ripples. The formation of flow marks originates from the "stick-slip" behavior of the melt flow front on the cavity wall — after the front melt contacts the cold mold wall, its viscosity rises and it temporarily stagnates, and the subsequent high-pressure melt pushes it forward again; this repeats to form ripple marks. Although flow marks mainly affect appearance, in severe cases they also imply that the melt front temperature is too low, affecting weld strength.

1. Process parameter factors: low melt temperature, low mold temperature, too slow injection speed, insufficient holding pressure.

1. Process parameter optimization and adjustment: increase barrel and mold temperature, speed up injection speed, increase holding pressure. 2. Systematic troubleshooting method: troubleshoot item by item in the order of "parameters -> material -> 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 fluidity of the raw material; further check mold venting and gate design; finally check the mechanical condition of the equipment (check 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) evaluation. For recurring problems, use fishbone diagram or 5Why analysis to trace the root cause, and fix the countermeasures as PFMEA control points.

This problem is a typical manifestation of flow marks in '2079851475616104452; 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 into the equipment and mold levels.