Finding Maximum and Minimum Tolerance

[teng125]

what is the formula to find maximum and minimum tolerance??

pls help
thanx

 

[Office_Shredder]

You mean, given the +/- % tolerance?

For example, if you have a measurement of 3.00 mm with a tolerance of +/- 5%, then your max and min are 95% and 105% of 3.00 mm, so .95*3.00m and 1.05*3.00

 

[teng125]

if i am given only the lower,upper deviations and the normality number such as 60P6,how can i find the the max and min tolerance??

 

[Meson]

Normally, we have three tables:
i) Base Tolerances Table
ii) Base Deviations of Shafts Table
iii) Base Deviations of Holes Table

all are in micrometer and are of DIN-ISO 286 T1.

Steps to determine the max and min tolerance:
From 60P6, we know that it refers to a hole with inner diameter 60 mm.

In the Base Tolerances Table, search for the nominal size range that the inner diameter of the hole lies in. So it should be (50-80) mm.

Then refer to the base tolerance scale IT and look for the grade number 6. You will obtain the corresponding base tolerance (with respect to the nominal range) of 19.

After that, refer to Base Deviations of Holes Table. Look for the capital letter P column and nominal range 50-65 mm row. You will see a value of -32. This is the upper deviation EI. The lower deviation EI can be found by $$EI=ES-IT=(-32-19) \mu m=-51$$

Because base tolerance IT is 6, which is up to IT 7, a $$\delta$$ has to added. In this case $$\delta =6 \mu m$$. So $$ES_{corrected}=-32+\delta =-32+6=-26 \mu m$$. So as $$EI_{corrected}=-45 \mu m$$.

Hence, the maximum tolerance is 60 mm + (-26 micrometer) = 59.974 mm while the minumum tolerance is 60 mm + (-45 micrometer) = 59.955 mm

And that's it

EDIT: Latex problem solved

 

[teng125]

but i think what u have written is the way to find the max and min diameter right??

 

[Meson]

yes, and to do so the maximum and minimum deviations have to be calculated as in ES and EI.

 

[teng125]

so maximum and minimum tolerance is the same as max and min diameter ??

 

[Meson]

The maximum tolerance is ES - EI = IT that is the base tolerance 19 micrometer. It is the same as taking maximum diameter - minimum diameter = IT = 19 micrometer in this case.

 

[teng125]

can you pls give me the formulas for maximum tolerance ,min tolerance , max interference and min interference ??

 

[Meson]

For either a bore or a shaft alone, there is only maximum tolerance calculated with the formula given in the previous post.

For a bore-shaft system, for example 60H7/r6, then there are maximum and minimum tolerance. In this case, the maximum tolerance is the maximum tolerance of the bore minus the minimum tolerance of the shaft, that is
$$\delta_{max}=E_{s, bore}-E_{i, shaft}$$
while the minimum tolerance is the difference between the minimum tolerance of the bore and the maximum tolerance of the shaft, that is
$$\delta_{min}=E_{s, shaft}-E_{i, bore}$$

These are applied to both clearance and interference as well.