Limits, Fits And Tolerances Flashcards
Limits of size?
Limits of size of the largest (upper limit) size and the smallest (lower limit) size apart can be and still be acceptable.
What is actual size?
Actual size exact measurement
Maximum material condition (MMC)
Maximum material condition is were both mating parts have the most mass (metal) which would be the smallest hole and the largest shaft
What is Tolerance?
The total amount of variation permitted in the size of duplicate parts.
What is unilateral tolerance?
Is in one direction only from basic size and there’s no variation (zero) in the other direction.
What is Bilateral Tolerance?
Tolerances in both directions (equally or an equally) from basic size.
What is Limit dimension?
Only the maximum and minimum dimensions of a part are specified.
What is allowance?
Is the initial difference between two mating parts at maximum material condition.
What is positive allowance?
The hole is to be larger than the shaft.
What is negative allowance
When the hole was smaller than the shaft.
What is fit?
Describes the tightness or looseness between two mating parts.
What is interference fit?
Is when the smallest shaft is larger than the largest hole.
What is clearance fit?
Is when the largest shaft will fit into the smallest hole.
What is transition fit?
Occurs when the limits of size result in either an interference fit or clearance fit used in applications were accurate location is important.
What is hole basis system?
Is more common and recommended for General use.
The hole is considered the master size.
