7. How to avoid sink mark when molding plastic products?

Instead it is part thickness distribution with respect to injection point (gate) towards the extreme point on the melt flow path i.e, last fill point. A good injection molding part thickness should always decrease (not uniform) along the flow path and that thickness decrease magnitude is the prime factor responsible for sink marks.

Basically injection (processing) pressure and temperature are primarily polymer and then mold and machine dependent. i.e., injection melt state variables., So part form / features have very less to do with setting injection melt state.However a good control to prevent sinks can be achieved by increasing packing intensification rate, this technique can considerably compensate thickness distribution variance also, which is quite often.