Tolerances & Fits in Engineering Drawings Flashcards

A shaft is specified as ⌀50 -0.010/-0.030. What is the maximum shaft diameter?

Answer: 49.990 mm

The upper deviation is -0.010, so maximum shaft diameter = 50.000 - 0.010 = 49.990 mm.

Which ANSI/ISO fit system uses the hole as the fixed reference with H designation?

Answer: Hole-basis system

In the hole-basis system, the hole deviation is fixed (H) and the shaft deviation varies to achieve the desired fit.

A clearance fit is achieved when the minimum clearance between mating parts is:

Answer: Positive

A clearance fit always has a positive minimum clearance, meaning the shaft is always smaller than the hole.

What does the term 'allowance' refer to in tolerance and fit terminology?

Answer: The minimum clearance or maximum interference between mating parts

Allowance is the intentional difference between mating parts — minimum clearance for clearance fits or maximum interference for interference fits.

A hole tolerance is specified as ⌀25 H7. If H7 corresponds to +0.021/0.000, what is the minimum hole diameter?

Answer: 25.000 mm

For H-designation holes, the lower deviation is always zero, so minimum hole diameter equals the nominal size of 25.000 mm.

Which type of tolerance expression shows deviation equally in both directions from nominal?

Answer: Bilateral tolerance

A bilateral tolerance distributes the allowable variation equally on both sides of the nominal value, such as 25.00 ± 0.05.

In an interference fit, which condition is always true at maximum material condition (MMC)?

Answer: Interference is maximized

At MMC — largest shaft and smallest hole — interference is at its maximum value in an interference fit.