Why does BIS tolerance notation specify hole designation before shaft designation in fits?
To indicate the hole basis or shaft basis relationship used for the fit
In the BIS/ISO system of limits and fits a fit is written by pairing a hole tolerance symbol with a shaft tolerance symbol, for example H7/g6.
By convention the hole designation is always placed first, and that leading symbol declares the basis on which the fit is built.
A capital letter first, such as H, signals the hole-basis system, where the hole tolerance is held constant and different shafts are used to obtain clearance, transition or interference.
Had a shaft symbol led, it would indicate the shaft-basis system, where the shaft is kept constant instead; so the order itself carries the hole-basis-versus-shaft-basis information.
The order is not there to state the shaft's tolerance magnitude first, nor to fix an inspection sequence, nor to give the actual machined size, which is read from the part, not the notation.
The purpose of writing the hole before the shaft is therefore to declare which basis governs the fit.
Hence, the answer is To indicate the hole basis or shaft basis relationship used for the fit.
Similar Questions
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The number of fundamental tolerance in the Indian Standard System are:
In an assembly, Hole size is smaller than shaft size then this type of fit is known as ______
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The tolerance limit is 50.3 ± 0.05 mm.
What is this shown?
When tolerance is given on both sides of the basic dimension, it is called:
- When tolerance is given on one side of the basic dimension, it is called:
- The measured size of the dimension of a component is called:
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Important Questions from Limits and Fits
Which one of the following dimensions shows the largest tolerance?
In mass production, parts made to definite limit of error is called as ______
Name the fit, in which the shaft is cooled below the room temperature until it fits into the hole, then assembly is allowed to attain room temperature.
The type of fit in which the female part is fitted when male part is in hot condition is called _____
Which of the following fit is produced with the shaft dia 25.025 and bore dia of 24.994?
