What Is a Small Entity?

The dimensional tolerance is used to control the dimensional error of the part to ensure the dimensional accuracy requirements of the part; the dimensional tolerance is used to control the dimensional error of the part to ensure the accuracy requirements of the part. They are two aspects that affect part quality.

Maximum entity requirements

Right!

The dimensional tolerance is used to control the dimensional error of the part to ensure the dimensional accuracy requirements of the part; the form and position tolerance is used to control the dimensional error of the part to ensure the part's

The maximum entity requirement (MMC) is one of the related requirements and can be applied to both the measured element and the reference center element.

When the largest entity requirement is applied to the element under test,

1) The largest entity is required for the element under test

When the maximum entity requirement is applied to the measured element, the actual contour of the measured element shall comply with its maximum physical effect boundary, that is, the maximum physical effect boundary shall not be exceeded everywhere at a given length. In other words, its external acting size must not exceed its maximum solid effective size. Moreover, its local actual size must not exceed the maximum and minimum solid sizes.

The maximum solid size of the hole is the minimum internal diameter required:

DfeDMV and DM = DminDaDL = Dmax

The maximum solid size of the shaft is the required maximum outer diameter:

dfedMV and dm = dmaxdadL = dmin

It is marked only when required during assembly.

When the maximum entity requirement is applied to the measured element, the form and position tolerance value of the measured element is given when the element is in the maximum entity state. When the actual contour of the measured element deviates from its maximum solid state, that is, its actual size deviates from the maximum solid size, the form error value can exceed the shape tolerance value given under the maximum solid state, that is, the shape position The difference can increase. If the measured element adopts the maximum physical requirement, the form and position tolerance value given by it is zero, which is called the zero form and geometric tolerance of the maximum entity requirement, and it is expressed as "0 M".

When the maximum entity requirement is applied to the center feature, the maximum effective size of the entity to be measured is allowed to increase the corresponding form and position tolerance value.