Bonus tolerance occurs when the actual size moves toward which boundary?

Bonus tolerance occurs when the actual size moves toward which boundary?

• A. Opposite material boundary from MMC
• B. MMC boundary
• C. LMC boundary
• D. Datum boundary

Answer: (A)

Bonus tolerance is extra tolerance that becomes available when the size of a feature moves away from its MMC toward the opposite material boundary. In practice, for an external feature, MMC is the largest size and the opposite boundary is the smallest size (the least material). As the actual size decreases toward that boundary, the tolerance zone for the related geometric control (such as true position) enlarges, giving additional permissible deviation. For example, if a shaft has a positional tolerance tied to MMC and the maximum material condition is 10.000 mm, with a true position tolerance of 0.05 mm, and the actual size is 9.900 mm (toward the opposite boundary from MMC), the bonus tolerance added is 0.100 mm, making the total tolerance 0.15 mm. No bonus occurs when the size is at MMC. Thus, bonus tolerance occurs as the size moves toward the boundary opposite MMC (toward the least material for external features).

Bonus tolerance is extra tolerance that becomes available when the size of a feature moves away from its MMC toward the opposite material boundary. In practice, for an external feature, MMC is the largest size and the opposite boundary is the smallest size (the least material). As the actual size decreases toward that boundary, the tolerance zone for the related geometric control (such as true position) enlarges, giving additional permissible deviation.

For example, if a shaft has a positional tolerance tied to MMC and the maximum material condition is 10.000 mm, with a true position tolerance of 0.05 mm, and the actual size is 9.900 mm (toward the opposite boundary from MMC), the bonus tolerance added is 0.100 mm, making the total tolerance 0.15 mm. No bonus occurs when the size is at MMC.

Thus, bonus tolerance occurs as the size moves toward the boundary opposite MMC (toward the least material for external features).