- #1
teng125
- 416
- 0
what is the formula to find maximum and minimum tolerance??
pls help
thanx
pls help
thanx
Finding Maximum and Minimum Tolerance
Click For Summary
Discussion Overview
The discussion revolves around the formulas and methods for calculating maximum and minimum tolerances in engineering contexts, particularly related to dimensional tolerances for mechanical components. Participants explore various scenarios, including the use of specific tolerance grades and deviations, and the relationship between tolerances and diameters.
Discussion Character
- Technical explanation
- Mathematical reasoning
- Debate/contested
Main Points Raised
- One participant asks for the formula to find maximum and minimum tolerance.
- Another participant explains that with a given measurement and percentage tolerance, the maximum and minimum can be calculated as a percentage of that measurement.
- A participant inquires about calculating maximum and minimum tolerances when only lower and upper deviations and a nominal size (e.g., 60P6) are provided.
- Discussion includes reference to specific tables (Base Tolerances Table, Base Deviations of Shafts Table, Base Deviations of Holes Table) used to determine tolerances based on nominal sizes.
- One participant details a step-by-step method to derive maximum and minimum tolerances from a given nominal size and tolerance grade, including calculations involving deviations.
- There is a clarification that the method described pertains to finding maximum and minimum diameters, which some participants question.
- Participants discuss the equivalence of maximum and minimum tolerances to maximum and minimum diameters, with some asserting they are the same.
- A request is made for formulas related to maximum and minimum tolerances, as well as interference tolerances.
- One participant explains how to calculate maximum and minimum tolerances for a bore-shaft system, providing specific formulas for both clearance and interference scenarios.
Areas of Agreement / Disagreement
Participants express differing views on whether maximum and minimum tolerances are equivalent to maximum and minimum diameters. The discussion includes multiple approaches and interpretations without reaching a consensus on some aspects.
Contextual Notes
Participants reference specific standards (DIN-ISO 286 T1) and tables, indicating that the discussion is dependent on these definitions and may not apply universally. Some calculations involve assumptions that are not explicitly stated, and there are unresolved mathematical steps in the explanations provided.
- #2
Office_Shredder
Staff Emeritus
Science Advisor
Gold Member
- 5,706
- 1,592
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
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
- #3
teng125
- 416
- 0
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??
- #4
Meson
- 29
- 0
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
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
Last edited:
- #5
teng125
- 416
- 0
but i think what u have written is the way to find the max and min diameter right??
- #6
Meson
- 29
- 0
yes, and to do so the maximum and minimum deviations have to be calculated as in ES and EI.
- #7
teng125
- 416
- 0
so maximum and minimum tolerance is the same as max and min diameter ??
- #8
Meson
- 29
- 0
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.
- #9
teng125
- 416
- 0
can you pls give me the formulas for maximum tolerance ,min tolerance , max interference and min interference ??
- #10
Meson
- 29
- 0
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.
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.
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