Measuring Flashcards
Nominal size
Refers to an imperial standard size, which is used for the purpose of general identification
Actual size
The measured size of a component is the actual (measured) size or dimensions
Basic size
The theoretical size to which the tolerances are applied
Limits of size
Limits of size are the largest size and smallest size a part can be and still be acceptable
MMC
Maximum material condition
Maximum metal condition
The smallest amount of metal has been removed
LMC
Least metal condition
Least metal condition
The largest amount of metal has been removed
Tolerance
The total amount of variation permitted in the size duplicate parts
Tolerance dimensioning can be specified by (2)
A plus-minus tolerance
A limit dimension
The two methods to express plus-minus dimensioning are
Unilateral
Bilateral
What tolerance is in one direction only from basic size and there is no variation (zero) in the other direction
Unilateral tolerance
Bilateral tolerance is
In both directions (equally and unequally) from basic size
Limit dimension method only the (2)
Maximum and minimum dimensions of the part are specified
The intentional difference between two mating parts
Allowance
The hole is to be larger (+) than the shaft
Positive allowance
When the hole is smaller (-) than the shaft
Negative allowance
The term fit describes
The tightness or looseness between two mating parts
Fit types (3)
Interference fit
Clearance fit
Transition fits
Interference fit is
The total tolerances do not exceed the allowance (negative allowance)
Clearance fit has a
Positive allowance
Transition fits
Have negative allowance but the total tolerances exceed the allowance
An interference fit is when the
Smallest shaft is larger than the largest hole
Clearance fit is when
The largest shaft will fit into the smallest hole (mmc)
A ______ fit occurs when the limits of size result in either an interference or clearance fit
Transition fit
Standard measuring temperature is
20° C or 68° F
