A Defect Name Is Half a Corrective Action
Fill-related defects
A cold shut is a seam where two metal fronts met without fusing, usually because one front cooled too far before they joined. It shows as a line, often on a thin section or at the far end of flow, and it points to fill speed, die temperature or gate position rather than to metal quality. A short shot is simply incomplete fill, and the useful question is whether it is consistent across shots or intermittent.
Blistering is gas trapped under the skin expanding after ejection, visible as a raised bubble or felt as a soft spot. It is a gas problem, so it leads back to melt gas content, die lubrication volume and venting. Flow marks and cold laps are cosmetic in many applications and structural in some; the drawing should say which, because the remedy cost differs.
Die and ejection related
Flash is metal escaping the parting line or a slide joint, driven by insufficient clamp force, worn parting surfaces or excessive fill pressure. Trimming removes the symptom; the cause is a die condition or a machine setting. Solder is metal adhering to the die surface, typically where die temperature ran low or lubrication was inconsistent, and it worsens if not dressed out.
Drag and pull marks come from ejection or from a draft angle that is too small for the surface being ejected. Ejector pin marks are a designed consequence of where the part is pushed off, which is why their position belongs in the DFM discussion rather than in the defect report. Reading a defect list without the location on the part rarely leads anywhere.
FAQ
What is a cold shut?
A seam where two flow fronts met without fusing, usually because one front cooled before they joined. It points to fill speed, die temperature or gate position.
Is flash a trimming problem?
Trimming removes the flash but not the cause. Flash comes from clamp force, worn parting surfaces or excessive fill pressure.
What causes solder on a die?
Metal adhering to the die surface, typically where die temperature is low or lubrication is inconsistent. Left undressed, it grows and damages the cavity.
Why does the location of a defect matter?
Because the same defect name can have different causes depending on where it appears: near the gate, at the end of flow, or at an ejector pin each point to different settings.
All figures above refer to standard product data sheets; final confirmation is subject to written quotation.