Tolerances & Fits in Engineering Drawings Flashcards

A transition fit is best described as a fit where:

Answer: Either clearance or interference may result depending on actual sizes

A transition fit has tolerance zones that overlap, so actual assembled parts may have either a small clearance or a small interference.

What is the tolerance grade (IT grade) system used to define?

Answer: The magnitude of tolerance relative to nominal size

IT (International Tolerance) grades define the size of the tolerance zone; higher IT numbers indicate larger tolerances.

A part drawing shows a dimension of 40.00 +0.05/−0.00. This is an example of which tolerance type?

Answer: Unilateral tolerance (plus only)

When all tolerance variation is permitted in only one direction from nominal (here, only positive), it is a unilateral tolerance.

When specifying a press fit for a steel pin in a housing, which fit category is most appropriate?

Answer: H7/p6

H7/p6 is a standard interference (press) fit designation where the shaft is larger than the hole at all conditions.

What is meant by 'maximum material condition' (MMC) for a hole feature?

Answer: The hole is at its smallest diameter

For a hole, MMC corresponds to the smallest permissible diameter because at that size the part has the most material.

The fundamental deviation in ISO limits and fits defines:

Answer: The position of the tolerance zone relative to nominal size

The fundamental deviation (indicated by a letter) sets where the tolerance zone starts — how far it is offset from the nominal size.

Which fit is typically used for bearings that must rotate freely with minimal play?

Answer: H7/f7 (running clearance fit)

H7/f7 provides a reliable running clearance suitable for bearings and rotating shafts that need free rotation with controlled play.