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In plastics injection molding, parting lines and weld lines are important subjects for engineers, product designers and mold designers. The parting line refers to a line on the part that is created where the two halves of the mold come together; it is the dividing line on sample that separate cavity and core.

When the mold is closed and the molten plastic is injected... a faint, sometimes unnoticeable line on the plastic part will be present. This line usually doesn’t affect the overall shape or dimensions of the part, but can be visually noticeable to varying degrees, depending on mold finish, material type, material color and processing parameters.

The parting line will usually be determined by the geometry of the part. The mold designer’s goal is to choose a location for the parting line that will create the most robust tooling design, while at the same time making it less noticeable.

The direction of mold opening determines the parting line. Consider the parting line for cosmetic parts. The parting line location can effect the cost of mold making and secondary operations needed to finish the part.

At V1, we include in our DFM report a section for parting lines. Our team can suggest where the parting lines should be located and together we can confirm before cutting steel to build the tooling. This is a critical part in the early stages of a project so we make sure to include the client in these big decisions.

Learn more about V1's projects; we've manufactured plastic injection molds for customers all over the world. If you're located in México, contact our sales team to get a timely response today.