Limit Fit and Tolerances
What is tolerances ?
In clearance fit the difference between the maximum size of the hole and the minimum size of the shaft is known as the Maximum clearance and the difference between the minimum size of the hole and the maximum size of the shaft is known as the Minimum clearance.
In Interference fit the difference between the maximum size of the shaft and the minimum size of the hole is known as the Maximum Interference and the difference between the minimum size of the shaft and the maximum size of the hole is known as the Minimum Interference.
In transition fit, the tolerance zones are overlapped. I can provide both Interference and clearance as well based on the application but at the very small amount.
In engineering practice, while manufacturing a part it is not possible to manufacture the part to its exact dimensions. Therefore some variation in dimensions is allowed while manufacturing a component. This permissible variation is called tolerances. Tolerance is basically the difference between maximum and minimum permissible size of the component.
What is limit ?
The maximum permissible size of component as well as minimum permissible size of component is known as Upper limit and lower limit respectively.
What is Fit ?
Fit is defined as a degree of tightness or looseness between two mating parts to perform definite function when they are assembled together.
Types of fit in engineering
There are so many types of fits are implemented. But they all are categorised into the three categories. The following are the 3 different types of Fits in Engineering
- Clearance Fit
- Interference Fit
- Transition Fit
1) Clearance Fit
This means there is a gap between the two mating parts. Let’s see the following schematic representation of clearance fit. The diameter of the shaft is smaller than the diameter of the hole. There is a clearance between the shaft and the hole. Hence the shaft can easily slide into the hole. Below figure shows tolerance zone of shaft and hole.
2) Interference Fit
There is no gap between the faces and there will be an intersecting of material will occur. In the following schematic representation of the Interference fit. The diameter of the shaft is larger than the hole diameter. There will be the intersection of two mating components will be occurred. Hence the shaft will need additional force to fit into the hole.
3) Transition Fit
Transition fit is neither loose nor tight as like clearance fit and interference fit. The tolerance zones of the shaft and the hole will be overlapped between the interference and clearance fits. See the following schematic representation of the transition fit.
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