Profile tolerances control the shape of a feature’s outline or surface relative to its true (theoretical) geometry. They are very versatile and can control form, orientation, and location at the same time.
Key Characteristics
- Can reference datums (to control location/orientation) or not (form only)
- Tolerance is typically evenly distributed (±) about the true profile
- Works well for complex and freeform geometry
Many engineers use Profile of a Surface as a powerful replacement for multiple tolerances (form + orientation + location) in a single callout—especially in modern CAD/CAM and CMM inspection.
1. Profile of a Line
Controls the shape of a 2D cross-sectional line
- Applies to any single cross-section
- Tolerance zone: two parallel curves offset from the true profile
Used for features like airfoil sections, cam profiles, or curved edges.
2. Profile of a Surface
Controls the shape of an entire 3D surface.
- Applies across the whole surface
- Tolerance zone: two offset surfaces around the true geometry
Used for complex shapes like castings, molded parts, or aerodynamic surfaces
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