What is a feature control frame (FCF)?

What is a feature control frame (FCF)?

• A. A datum frame that lists datum references.
• B. The GD&T annotation that lists the geometric tolerance, the tolerance value, any modifiers, and the datum references.
• C. A device used to locate the part in a fixture.
• D. A symbol indicating true position.

Answer: (B)

The feature control frame is the GD&T annotation that communicates the exact geometric requirement for a feature. It explicitly lists the type of tolerance (such as true position, runout, etc.), the tolerance value (and any size or zone modifiers, like diameter), and the datum references that establish the measurement frame used to evaluate the feature. This frame ties the tolerance to the datums, so you know not only how much a feature can deviate, but also relative to which datums that deviation is measured. For example, a true position tolerance might specify a cylindrical tolerance zone of a certain diameter located relative to datums A and B. The datums define the coordinate system used during inspection, and the tolerance value defines how much the feature is allowed to move within that frame. It’s different from a datum frame, which would only list datum references, not the full tolerance rule. It’s not a device used to locate a part in a fixture, and it’s not just a symbol by itself. The feature control frame provides the complete geometric requirement for evaluating that feature.

The feature control frame is the GD&T annotation that communicates the exact geometric requirement for a feature. It explicitly lists the type of tolerance (such as true position, runout, etc.), the tolerance value (and any size or zone modifiers, like diameter), and the datum references that establish the measurement frame used to evaluate the feature.

This frame ties the tolerance to the datums, so you know not only how much a feature can deviate, but also relative to which datums that deviation is measured. For example, a true position tolerance might specify a cylindrical tolerance zone of a certain diameter located relative to datums A and B. The datums define the coordinate system used during inspection, and the tolerance value defines how much the feature is allowed to move within that frame.

It’s different from a datum frame, which would only list datum references, not the full tolerance rule. It’s not a device used to locate a part in a fixture, and it’s not just a symbol by itself. The feature control frame provides the complete geometric requirement for evaluating that feature.