What does Unilateral Tolerance allow in terms of dimension variation?

• A. Variation in either direction equally
• B. Variation only in one direction
• C. Variation only if there are negative values
• D. Variation only in larger sizes

Answer: (B)

Unilateral Tolerance permits dimension variation exclusively in one direction, either positive or negative, from a specified nominal dimension. This means that a dimension can be more significant or smaller than the nominal value, but only from one side. For example, if a feature has a nominal dimension of 10 mm with a unilateral tolerance of +2 mm, the acceptable size range would be from 10 mm to 12 mm. This approach allows for more controlled manufacturing limits when design requirements need to ensure specific clearance or fit characteristics.

In contrast, other forms of tolerance, such as bilateral tolerance, allow variation in both directions equally, which is not aligned with the unilateral concept. The focus of unilateral tolerance is to enforce stricter limits in one dimension while giving leniency in the other, thus accommodating specific design intentions more effectively.