A parting line is the location where separate parts of a mold or die come together. It is defined in the ASME Y14.8M standard as the separation between mold or die segments. Parting lines can often be seen on parts that are cast, molded, or forged, unless they have been removed by another manufacturing process. In Figure 1, below, you can see the parting line on a USB drive.
Figure 1: Parting line on a USB drive
To indicate a parting line on a drawing, a phantom line is used with a parting line symbol to show the location of the parting line. An example of how to indicate this correctly on a print is shown in Figure 2. The parting line for the part shown is highlighted in green.
Figure 2: Parting line example
If the parting line is not dimensioned on the drawing, the location of the parting line is up to the manufacturer’s discretion.
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