The white edge is a special injection defect of modified polyethylene and plexiglass, and most of it appears on the edge of the part near the parting surface. The white edge is an aggregate composed of a plurality of stretched orientation molecules which are straight with the flow direction and fine intervals between them. There is still a polymer connecting phase in the direction of the white side, so the white edge is not a crack. Under proper heating, the stretched oriented molecules may return to a natural bending state and the white edge may be degraded.

Plastic mold manufacturers solutions:

Attention should be paid to the close fitting of the parting surface of the template, especially the area around the cavity, which must be under a truly sufficient clamping force to prevent longitudinal and lateral expansion.

Decrease the injection pressure, timing and amount of material to reduce the orientation of the molecules.

Applying an oil-based release agent to the white side of the die face, on the one hand, makes this position less prone to heat transfer, and maintains a higher temperature at a higher temperature. On the other hand, it may cause the white edge to be pressed to reduce the occurrence of white edges.