Bubbles trapped inside plastic parts can cause circular protrusions on the surface, as shown in the Figure. These voids can occur not only in thick wall sections but also in other areas, with varying ...
Gloss marks — also known as stress shadows or burnish marks — are localized shiny spots on the surface of injection molded parts. They are a form of stress concentration and typically appear as glos...
Silver streaks (also known as silver marks or mica marks) are spray‑like blemishes that appear on the surface of molded parts, radiating outward from the gate in a fan‑shaped pattern, as shown in th...
Weld lines form where two melt fronts meet inside the mold cavity. Long flow paths cause the melt to cool, and trapped air prevents proper fusion, resulting in weak, visible lines. This article outlin...
Injection pressure is the force that pushes molten plastic through the nozzle, runners, and cavity. It overcomes flow resistance and also compacts the melt to compensate for shrinkage. The pressure va...
Surface peeling ( Delamination) is a common defect in injection molded parts, where thin layers separate from the surface. Understanding the root causes is essential for producing high‑quality parts....
During injection molding, plastic parts may sometimes show unwanted color changes — such as yellowing, browning, or dark streaks. This defect is often referred to as discoloration. Understanding the ...
What Is Molding Shrinkage?Molding shrinkage is the ratio of dimensional change caused by cooling after injection molding to the original cavity size. In simple terms, it tells you how much a plastic p...
Dimensional accuracy is a critical quality for plastic parts, but it is influenced by many complex factors. Understanding these factors is essential for setting realistic tolerances and producing cons...
What Causes Deformation in Plastic Parts?Deformation in molded plastic parts — including warpage, cracking, bending, and twisting — is primarily caused by residual internal stresses. These stresses ...
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