Injection sink marks: check the part and process together
When a customer sends us a part with sink marks, we first look at rib and boss thickness, gate position and the relation between the visible mark and the internal section. The surface may continue to move after ejection, so inspection time must also be fixed.
Injection troubleshooting
When a customer sends us a part with sink marks, we first look at rib and boss thickness, gate position and the relation between the visible mark and the internal section. The surface may continue to move after ejection, so inspection time must also be fixed.
We compare packing pressure and time, melt and mould temperature, cooling balance, shot weight and part weight before assigning the issue to the material. If a formulation trial is warranted, the same mould, cavity and visual standard are used for the control and trial material.
Mark the defect on the drawing
Provide the part, drawing, resin grade, cavity number and current cycle. Mark when the sink mark becomes visible and which surface is customer-facing. This lets us decide whether to begin with process correction, a material comparison or both.