Скачать или смотреть What are limits, fits and tolerances?

Welcome back MechanicaLEi, did you know that limits fits and tolerances highly influence both minor and major decisions ranging from material selection to the entire cost of manufactured product? This makes us wonder, what are limits, fits and tolerances? Before we jump in check out the previous part of this series to learn about what thread designation is?
First, let’s clear out some terminology: The term shaft refers not only to the diameter of a circular shaft but to any external dimension on a component and the term hole refers not only to the diameter of a circular hole but to any internal dimension of a component. Now, the term limits or limits of size refer to the two extreme permissible sizes for a dimension of a part, between which the actual size should lie. The largest permissible size for a dimension is called upper limit, whereas the smallest size is called lower limit. Fit refers to the degree of tightness or looseness between two mating parts. Depending upon the actual limits of the hole and shaft they may be classified into the following three types: In clearance fit, which is the first type, the minimum size of the hole is either greater than or, equal to the maximum size of the shaft, so that the shaft can rotate or slide as per the purpose of the assembled members. A fit that everywhere provides interference between the hole and shaft when assembled, is known as interference fit. This is the second type of fit. In interference fit, the maximum size of the hole is either smaller or equal to the minimum size of the shaft. Finally, A fit which may provide either a clearance or interference between the shaft and hole when assembled, depending on the actual sizes of the manufactured shaft and hole, is known as Transition fit.
The term tolerance refers to the difference between the upper limit and lower limit of a dimension. In other words, tolerance is the maximum permissible variation in a dimension. The tolerance may be of two types i.e. unilateral or bilateral. When the tolerance is allowed on one side of the nominal size, then it is said to be unilateral system of tolerance. When the tolerance is allowed on both sides of the nominal size then it is said to be bilateral system of tolerance. Hence, we first saw what limits and fits are and then went on to see what tolerances are?
In the next episode of MechanicaLEi find out what assembly drawing is?


Attributions:

Doh De Oh by Kevin MacLeod is licensed under a Creative Commons Attribution licence (https://creativecommons.org/licenses/...)
Source: http://incompetech.com/music/royalty-...
Artist: http://incompetech.com/

Subtle Library by Fabian Measures (http://freemusicarchive.org/music/Fab...) is licensed under a Creative Commons Attribution licence ( https://creativecommons.org/licenses/...)
Source: http://freemusicarchive.org/music/Fab...