GD&T Symbol Guide
Parting Line
Marks where mold or die segments meet on a cast, molded, or forged part.
Definition
A parting line is the separation between mold or die segments.
It may be visible on cast, molded, or forged parts unless removed by later processing.
Application
Use a phantom line and parting-line symbol to define the intended location on a drawing.
If the parting line is not dimensioned, its location may be left to the manufacturer.
Parting Line Drawing Use
Parting Line is read with the adjacent dimension, note, or feature control frame so inspection uses the intended feature definition.
3D Tolerance Zone
This symbol defines or modifies a size, shape, or manufacturing dimension rather than creating a GD&T tolerance zone by itself.
Inspection Method
Read the symbol with the attached dimension, note, or feature control frame before evaluating the feature.
Verify the controlled feature using the drawing's stated limits, datum setup, and any special notes tied to the symbol.
Worked Read: Parting Line
A drawing includes the Parting Line symbol with a related feature requirement.
Identify
PL
Recognize the Parting Line symbol and the feature it modifies.
Read
Adjacent value
Use the attached dimension, note, or frame cells as the controlling requirement.
Inspect
Per drawing
Measure the named feature using the specified interpretation rather than assuming a generic size check.
Parting Line clarifies how the feature is defined so the drawing and inspection method stay aligned.
Comparison Table
| Item | Controls | Typical Placement |
|---|---|---|
| Parting Line | Dimension interpretation | Next to a dimension, note, or frame |
| GD&T control | Geometric variation | Feature control frame |
| Datum reference | Measurement setup | Datum feature or frame cell |
Notes
This page is part of the drawing-symbol reference set rather than a standalone geometric tolerance category.
When the symbol modifies a feature control frame, read it together with the tolerance value and datum references.