The nature of flash: From the perspective of plastics, flash occurs because the pressure in the mold cavity exceeds the clamping force, or the mold is damaged.
1. Analyze at which stage does flash occur?
1. First look at the filling process (short shot products) to determine whether to adopt a staged molding method;
2. Determine at which stage the flash occurs, whether it is the filling stage or the feeding stage.

Second, the solution to flashing in the feeding stage
Reason analysis:
1) The pressure in the cavity is too large, the clamping force is insufficient, and the mold is expanded;
2) The filling speed is too slow, and the effective viscosity of the plastic is too high, resulting in increased pressure loss in the cavity, and flashing in the area with too much pressure;
3) During the feeding period, the mold is deformed.
For different reasons, possible solutions are:
1) Reduce the feeding pressure or reduce the feeding rate, and check whether the clamping force is appropriate;
2) Check the reasons for the change in the effective viscosity of the plastic (injection pressure integral during the filling stage), and adjust the process according to the specific reasons;
3) Measure the deformation of the mold and solve the deformation of the mold.

Third, the solution to flashing in the filling stage
Reason analysis:
Since the cavity is not filled during filling, it is usually not caused by the pressure in the cavity being too large to exceed the clamping force to expand the mold, so the possible reasons are:
1) During filling, the mold is deformed;
2) The mold is damaged or the fractal surface is not well matched;
3) Because the filling speed is too fast, or the basic reason for plastic: From the perspective of plastics, the flash occurs because the pressure in the mold cavity exceeds the clamping force, or the mold is damaged.
 For different reasons, possible solutions are:
1) Reduce the feeding pressure or reduce the feeding rate, and check whether the clamping force is appropriate;
2) Check the reasons for the change in the effective viscosity of the plastic (injection pressure integral during the filling stage), and adjust the process according to the specific reasons;
3) Measure the deformation of the mold and solve the deformation of the mold.

https://www.tengfeimold.com/product/home-appliance-mould-series/