Allowance:
It is the dimensional difference between two Mating Parts.
For example:
If the shaft size is less than the hole, then it is Positive allowance,
It the shaft size is greater than the hole, then it is Negative allowance.
Tolerance:
It is impossible to manufacture a component with exact dimensions.
So, during manufacturing, the dimensions will be taken as ∓ extra value.
It is the difference between Upper limit & lower limit of Dimensions.
![https://image.slidesharecdn.com/tolerancesandallowances-150602183546-lva1-app6892/95/tolerances-and-allowances-4-638.jpg?cb=1433270183](https://image.slidesharecdn.com/tolerancesandallowances-150602183546-lva1-app6892/95/tolerances-and-allowances-4-638.jpg?cb=1433270183)
It is the dimensional difference between two Mating Parts.
For example:
If the shaft size is less than the hole, then it is Positive allowance,
It the shaft size is greater than the hole, then it is Negative allowance.
Tolerance:
It is impossible to manufacture a component with exact dimensions.
So, during manufacturing, the dimensions will be taken as ∓ extra value.
It is the difference between Upper limit & lower limit of Dimensions.
![https://image.slidesharecdn.com/tolerancesandallowances-150602183546-lva1-app6892/95/tolerances-and-allowances-4-638.jpg?cb=1433270183](https://image.slidesharecdn.com/tolerancesandallowances-150602183546-lva1-app6892/95/tolerances-and-allowances-4-638.jpg?cb=1433270183)