Dec 14, 2023 · A weld line, often referred to as a knit line, represents the junction where two flow fronts converge during the molding process. This line typically emerges when these fronts are unable to seamlessly merge or “weld” together.

Mar 13, 2025 · Learn everything about weld line injection molding, including their causes, how they affect product quality, and effective strategies to minimize or eliminate them.

In manufacturing, the Weld line or Knit line or Meld line is the line where two flow fronts meet when there is the inability of two or more flow fronts to "knit" together, or "weld", during the molding process. These lines usually occur around holes or obstructions and cause locally weak areas in the molded part. [1] .

Jan 13, 2023 · What is Weld Line Defect? A weld line defect is a common problem in injection molded plastic parts. It occurs when two streams of molten plastic meet, cool and then fuse together during the injection molding process.

Oct 31, 2024 · In review, weld lines appear wherever two flow fronts fail to recombine during cavity filling in injection molding. Common causes include mold obstructions, multi-point gates, uneven walls, and poor venting.

Jun 9, 2023 · What is Weld Line in Injection Molding? The injection molding weld line, also known as a knit line, is a visible line or mark that occurs in an injection-molded part where two or more melt fronts meet and fuse together during the molding process.

Weld lines are common defects in injection-molded plastic parts that occur when two flow fronts of molten plastic meet and fuse together during the molding process. These lines can be visually noticeable and may affect the mechanical properties of the part.

Sep 16, 2024 · Weld lines in injection molding occur when two flow fronts of molten plastic converge but do not fully blend together in the mold cavity. This leaves a visible line, discoloration, or surface depression where the two fronts meet.

Mar 2, 2025 · Weld lines in injection molding are a common defect that occurs when two or more molten plastic flows meet but fail to fuse properly. These lines create weak points in the final part, reducing structural integrity, durability, and surface aesthetics.

Oct 28, 2024 · Discover the causes, effects, and solutions for weld lines in injection molding. Optimize mold design, material selection, and process for defect-free parts.