Hesitation, which occurs when the melt flow slows down or stops along a particular flow path, can lead to asymmetrical and unpredictable flow patterns.
Volumetric shrinkage is the contraction of polymer due to the change in temperature from melt temperature to ambient temperature.
Shear stress is stress applied to the melt as it flows through the mold. This stress is caused by excessive friction between layers of plastic flowing in the cavity.
Overpacking occurs when extra material is compressed in one flow path while other flow paths are still filling.
The racetrack effect occurs when flow races through thick sections of the cavity before the thin sections have filled.
Unbalanced flow is plastic completely filling some flow paths in the mold before other flow paths have filled.
Underflow is when a flow front reverses direction.