Industrial Engineering / Limits and Fits / Hole and shaft

HOLE/SHAFT BASIS SYSTEM 

Maximum clearance = Minimum clearance + hole tolerance + shaft tolerance

Allowance = Maximum metal condition of hole - Maximum metal condition of shaft.                    = Minimum clearance

Some of the selected Preferred Fits for Hole and Shaft Basis system are as under:

	Clearance Fit: If the lower limit of hole is larger than the upper limit of shaft. It is considered as clearance fit.
	Transition Fit: This type of fit appears when there is overlap in the tolerance zone.
	Interference Fit: This type of fit appears when maximum size of hole is smaller than the minimum size of shaft.

  1.    Hole basis system – In this system diameter of hole is kept constant and diameter of shaft varied to get different fits. Basic size or zero line is lower limit of hole i.e. maximum metal condition for hole.

 

   2.    Shaft basis system - In this system diameter of shaft is kept constant and diameter of hole varied to get different fits. Basic size or zero line is upper limit of shaft i.e. maximum metal condition for shaft.

 

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