How does bonus tolerance work in GDandT?

• A. It reduces the geometric tolerance based on feature size
• B. It is removed when a feature meets its MMC condition
• C. It applies to all features regardless of conditions
• D. It is added to the geometric tolerance when a feature departs from its MMC condition

Answer: (D)

Bonus tolerance is a concept in Geometric Dimensioning and Tolerancing (GD&T) that provides additional allowance beyond the specified geometric tolerance under certain conditions. When a feature departs from its Maximum Material Condition (MMC)—which is the condition where a feature contains the maximum amount of material while still meeting its dimensional specifications—it allows for a certain degree of variance.

When a feature’s size is less than its MMC, the bonus tolerance is essentially added to the original geometric tolerance. This means that the larger the feature, the more it can deviate from the ideal form while still being considered acceptable. This kind of flexibility in tolerancing is particularly useful in manufacturing because it accounts for variations in production that may not affect the functionality of a part.

This approach encourages the optimization of material use, providing an incentive for producing parts closer to their MMC, which can be important from both a cost and performance perspective. Understanding bonus tolerance is crucial for ensuring that parts meet functional requirements while also being easier and more economical to manufacture.