Measurement Flashcards
The standard size for the purpose of general identification.
.9975” shaft = 1.”
- 89mm shaft = 25mm
- 76mm shaft 25mm
Nominal size
The largest upper limit and smallest lower limit size a part can be and still be acceptable.
Example .9975
with +.0000, -.0012
= .9975,.9963
Limit of size
The total amount of variation permitted in part size.
Tolerance-the difference between maximum and minimum size
The intentional difference between 2 mating parts
Allowance
Refers to a variation or deviation either above or below the basic size
Unilateral tolerance
Only maximum and minimum dimension of a part are specified.
Shaft has a size of 1.005 and 1.000
Limit dimension
Has a negative allowance, shaft larger than hole
Interference fit
What is hole basis system?
The hole is the master size and the shaft component is manufactured to the tolerance required. Most common type of fitting.
What is shaft basis system
The shaft is considered the master size and the hole component is manufactured to the tolerance required to produced the desired fit. Less common
What 4 factors affect design tolerances of mating parts?
load
temperature
lubrication
metal type
When the limit of size result in either a interference or clearance fit.
Transition fit
Has a positive allowance, Hole bigger than shaft,
Clearance fit
Small amount of material removed
Smallest hole to largest shaft
Maximum metal conditition
Largest amount of metal removed
Largest hole to smallest shaft
Least metal condition
Theoretical size to which tolerances are applied
Basic Size
