Meaning
Geometric dimensioning and tolerancing parameter that defines a three-dimensional boundary around the true surface of a part. Application of profile tolerance controls the allowable deviation of any point on the surface relative to specified datums. It is particularly useful for complex curved surfaces where traditional linear dimensions fail to describe the required shape.
Boundary Zone
Two offset surfaces create a volume within which the actual part surface must lie. A profile tolerance specifies the total width of this zone, which may be distributed equally or unequally around the nominal geometry. This method provides a more comprehensive control than individual point measurements.
Molding Capability
Precision in tool making and consistency in process parameters determine the ability to stay within the defined limits. Holding a tight profile tolerance requires a stable melt temperature and consistent pack pressures to prevent surface variations. Warpage often causes parts to fall outside this zone even if the local dimensions are correct.
Inspection Method
Verification usually involves comparing a cloud of points from a laser scan or coordinate measuring machine to the original computer-aided design model. The profile tolerance allows for a visual representation of the deviations across the entire surface. This map helps engineers identify specific areas where the mold needs adjustment or the cooling needs optimization.
