How calculate tolrence
How to calculate tolrence for any dimensions, fector at which tolrence of dimensions depends
Accepted answer
Calculating tolerance involves determining the acceptable limits of variation in a physical dimension of a part or assembly. Tolerances are crucial in manufacturing and engineering to ensure that parts fit together properly and function as intended. Here are the basic steps to calculate tolerance:
1. Identify the Nominal Dimension
Determine the ideal or target measurement for the part. This is often referred to as the nominal dimension.
2. Determine the Tolerance Range
The tolerance range specifies the allowable deviation from the nominal dimension. This can be defined in several ways:
Bilateral Tolerance: Allows for deviation in both directions (positive and negative) from the nominal dimension.
Unilateral Tolerance: Allows for deviation in only one direction (either positive or negative) from the nominal dimension.
Limit Dimensions: Specifies the maximum and minimum acceptable dimensions directly.
3. Calculate the Upper and Lower Limits
For bilateral tolerance:
If the nominal dimension is š·
D, and the tolerance is Ā±š
Ā±T, then:
Upper Limit = D+T
Lower Limit = DāT
For unilateral tolerance:
If the nominal dimension is
š·, and the tolerance is +š or āš, then:
Upper Limit = š·+š
D+T (for positive tolerance)
Lower Limit = š·
D (for positive tolerance)
Upper Limit = š·
D (for negative tolerance)
Lower Limit = š·āš
DāT (for negative tolerance)
For limit dimensions:
The limits are specified directly as Upper Limit and Lower Limit.
4. Consider Geometric Tolerances (if applicable)
Geometric tolerances control the shape, orientation, and location of features. These can include flatness, roundness, perpendicularity, and more.
Example Calculation
Nominal Dimension: 50 mm
Bilateral Tolerance: Ā±0.1 mm
Upper Limit: 50+0.1=50.1
50+0.1=50.1 mm
Lower Limit: 50ā0.1=49.9
50ā0.1=49.9 mm
Factors to Consider
Functionality: Ensure that the tolerance allows the part to function correctly in its assembly.
Manufacturing Capability: Ensure that the specified tolerance can be achieved with the available manufacturing processes and equipment.
Cost: Tighter tolerances often increase manufacturing costs, so balance precision with cost-effectiveness.
Standards and Guidelines
Refer to relevant standards and guidelines, such as ISO 286 for linear tolerances or ASME Y14.5 for geometric dimensioning and tolerancing (GD&T).
If you need specific tolerances for a particular part or assembly, providing more details or context would help in offering a more tailored explanation.
2 Other answers
Hi @ER. ARUN KUMAR:
In general, dimensional tolerances are not calculated but are selected based on the type of fit that is desired in a coupling between parts (frequently cylindrical, but this is not exclusive).
The usual tolerance systems present tables that indicate the tolerances for certain ranges of dimensions and for the type of fit desired (clearance fit, interference fit, etc.). You can see an idea in the following link:
https://www.machiningdoctor.com/calculators/tolerances/
In addition to dimensional tolerances, there are geometric tolerances, which control shapes such as cylindrical shapes, because there are manufacturing processes and defects (this is an example) that generate cylindrical-looking parts (which are actually three-sided lobes with rounded corners) that if you measure them can perfectly respect the "dimensional tolerances" but, however, when you observe their real shape "they do not correspond to the desired geometry." You can see some of this as an introduction at:
https://en.wikipedia.org/wiki/Geometric_dimensioning_and_tolerancing
I hope you find it useful.
Kind regards!
Tolerance comes from the word tolerate. Tolerate from what? In a multi-body part system, every part is made with some standard dimensions and the deviation in that standard dimension which can be tolerated so that the whole system can be fabricated and assembled easily.
There has to be some space between the moving surfaces in a moving part system. With too small space, the parts may get stuck or with too much space the parts may wiggle. During manufacturing, a limit is set on maximum and minimum space allowed for smooth functioning which comes into the tolerancing from the standard dimension of a part.
Engineering judgment dictates tolerancing values and best practices are always used in deciding tolerance values.
