Basic reason: From the perspective of plastics, the occurrence of flash is due to the pressure in the mold cavity exceeding the clamping force, or due to damage to the mold.

1. First analyze the stage at which the flash is generated? (Filling stage, or filling stage)
1. First look at the filling process (short shot products) to determine whether to use a staged molding method;
2. Determine at which stage the flash occurs, whether it is the filling stage or the filling stage.

2. If the flash occurs during the filling stage
1. Reason analysis: Since the cavity is not filled during filling, it is usually not because the pressure in the cavity is too large to expand the mold beyond the clamping force, so the possible reasons are:
♦ During filling, the mold deforms;
♦ Damaged mold or poor coordination of fractal surface;
♦ Because the filling speed is too fast, or the plastic temperature is too high, the effective viscosity of the plastic is too low, and the flash appears in the area where the fractal surface is not tightly closed.
2. For different reasons, possible solutions are:
♦ Reduce the mold deformation by adding gaskets at the center of the template;
♦ Modify the mold;
♦ Slow down the injection speed or lower the plastic temperature.

3. If the flash occurs during the retraction phase
1. Reason analysis:
♦ The pressure in the cavity is too large, the clamping force is insufficient, and the mold is expanded;
♦ The filling speed is too slow, the effective viscosity of the plastic is too high, resulting in increased pressure loss in the cavity, and flash in areas where the pressure is too high;
♦ During packing, the mold deforms.
2. For different reasons, possible solutions are:
♦ Reduce the packing pressure or the packing rate, and check whether the clamping force is appropriate;
♦ Check the reason for the change of the effective viscosity of the plastic (the injection pressure integral during the filling phase), and adjust the process according to the specific reason;
♦ Measure the deformation of the mold to solve the mold deformation.