What does it mean for a tolerance to be “cumulative” across features?

What does it mean for a tolerance to be “cumulative” across features?

• A. The combined deviation of multiple features is independent.
• B. The combined deviation of multiple features is constrained relative to the DRF, not evaluated independently.
• C. Each feature tolerance is increased by others.
• D. There is no relation to the DRF.

Answer: (B)

Cumulative tolerancing means the variations of several features are considered together with respect to the datum reference frame, and the total deviation is constrained by the specified tolerance rather than judging each feature in isolation. In other words, you look at how far the features’ true positions drift from their ideal locations relative to the DRF, and the sum of those drifts must stay within the tolerance zone. This is why the correct description is that the combined deviation of multiple features is constrained relative to the DRF, not evaluated independently. For example, if two features share a 0.2 tolerance for true position relative to the DRF, and one is off by 0.12 while the other is off by 0.09, the total 0.21 would exceed the limit, so the part would fail. If one feature drifts more, the other must drift less to keep the cumulative deviation within the tolerance. The other options describe independence, per-feature increments, or no relation to the DRF, which do not reflect how cumulative tolerancing actually constrains groups of features.

Cumulative tolerancing means the variations of several features are considered together with respect to the datum reference frame, and the total deviation is constrained by the specified tolerance rather than judging each feature in isolation. In other words, you look at how far the features’ true positions drift from their ideal locations relative to the DRF, and the sum of those drifts must stay within the tolerance zone. This is why the correct description is that the combined deviation of multiple features is constrained relative to the DRF, not evaluated independently.

For example, if two features share a 0.2 tolerance for true position relative to the DRF, and one is off by 0.12 while the other is off by 0.09, the total 0.21 would exceed the limit, so the part would fail. If one feature drifts more, the other must drift less to keep the cumulative deviation within the tolerance.

The other options describe independence, per-feature increments, or no relation to the DRF, which do not reflect how cumulative tolerancing actually constrains groups of features.