Feature Control Frame

Definition

A feature control frame is a rectangular box used in geometric dimensioning and tolerancing (GD&T) that conveys specific information about the allowable variations for a feature on a part. It includes the geometric symbol, the control type, and any additional modifiers or datums needed to fully define how the feature should be controlled. Understanding how to read and interpret a feature control frame is essential for ensuring that parts are manufactured and assembled accurately according to design specifications.

5 Must Know Facts For Your Next Test

1. The feature control frame is crucial for communicating the required tolerances for complex parts, making it easier for manufacturers to meet design intent.
2. Each feature control frame contains several elements, including the geometric symbol that indicates the type of control (like position or perpendicularity), followed by the tolerance value.
3. Modifiers such as maximum material condition (MMC) or least material condition (LMC) can be added to a feature control frame to further define how the tolerance applies.
4. Feature control frames are often placed next to the corresponding feature on a technical drawing to provide clear guidance during manufacturing and inspection.
5. Understanding how to read feature control frames is important for quality control, as it helps ensure that parts fit together correctly and function as intended.

Review Questions

• How does a feature control frame enhance communication between designers and manufacturers?
  • A feature control frame enhances communication by providing precise information about the tolerances required for each feature on a part. This reduces ambiguity and helps manufacturers understand exactly how much variation is acceptable during production. By clearly indicating geometric controls and their specific requirements, feature control frames ensure that parts can be manufactured accurately according to the designer's intent.
• Discuss the significance of modifiers like maximum material condition (MMC) in a feature control frame and how they affect manufacturing processes.
  • Modifiers like maximum material condition (MMC) are significant because they add complexity to the way tolerances are applied. MMC indicates that the specified tolerance is only valid when a part contains its maximum amount of material. This means that as material is removed during machining, the tolerances can be relaxed. This impacts manufacturing processes by allowing greater flexibility and ensuring better fits in assembly while maintaining functionality.
• Evaluate how understanding feature control frames can lead to improvements in product quality and reduction of manufacturing defects.
  • Understanding feature control frames can significantly improve product quality by ensuring that all parties involved in manufacturing have a clear and uniform understanding of tolerances. This knowledge helps in designing inspection plans that accurately measure compliance with specifications. By reducing misinterpretations and aligning manufacturing processes with precise design requirements, companies can decrease defects and rework costs, leading to more reliable products and enhanced customer satisfaction.

Related terms

Geometric Dimensioning and Tolerancing (GD&T):

A system for defining and communicating engineering tolerances using symbols, rules, and conventions to describe the allowable variation in form, orientation, location, and size.

Datum: A reference point, line, or surface on a part used as a basis for measurement or to establish the location of features in GD&T.

Control Characteristic: A specific aspect of a feature that is being controlled or constrained by the tolerancing system, such as position, flatness, or circularity.