Under the premise of meeting the use requirements, a lower tolerance grade should be selected as much as possible to reduce processing costs. The application range of tolerance grades can be referred to Table 1, the tolerance grades that can be achieved by various processing methods can be referred to Table 2, and the selection and application of tolerance grades can be referred to Table 3.
In addition, when selecting tolerance grades, the requirements for surface roughness should also be considered.
For fits with a basic size ≤ 500mm, when the tolerance grade is higher than or equal to IT8, it is recommended to select a hole with a tolerance grade one level lower than the shaft; for fits with a tolerance grade lower than IT8 or a basic size > 500mm, it is recommended to select holes and shafts of the same grade.
