Nominal diameter

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The nominal diameter or the nominal diameter is the diameter of a technical component that is used to distinguish it from several similar but differently sized components.

The nominal diameter can be an outer diameter or an inner diameter (in the case of double designations of, for example, roller bearings, also both). In many cases the nominal diameter is the main component of a designation contained in standards : e.g. B. M10 for outer diameter 10 mm of a metric ( M ) thread .

In addition to screws and nuts , which are graded according to the thread diameter, there are many other machine elements in standardized, regular diameter gradations (simple: pins, bolts, washers, rings, etc.; more complex: roller bearings , ball bushings, etc.). The term nominal diameter is also used for semi-finished products (e.g. round bars and tubes ).

In the designation scheme for rolling bearings , the inner ring inside diameter and the outer ring outside diameter are listed. H. Rolling bearings are identified by two nominal diameters. The nominal diameter of spherical bushings is their inner diameter and that of the associated shafts is their outer diameter. The nominal diameter of pipes is nominal diameter called and is generally its inner diameter.

The nominal diameter is given in millimeters (mm) or inches (inches) depending on the industry . In bicycle tires as well as other tires , for. B. the specification in inches is still common.

The nominal diameter is an abstract dimension that deviates more or less from the actual diameter (actual diameter , which corresponds to the actual dimension , i.e. the real, measurable diameter) of the component. The term nominal diameter can also be used in the sense of nominal dimension on an individual component. In this context it is a generic term for the terms target , actual and limit dimensions that occur in dimensional tolerancing .

Examples of further technical objects that are designated by means of different nominal diameters are:

See also