Sectional Views

A sectional view is used when it is necessary to show the internal construction or shape of a part. The four main types of sectional views are the:

• Revolved Section: This view is often used to illustrate simple items with no interior parts. Basically, a revolved section shows how a part is sectioned and revolved to illustrate it from a different view.

FIGURE

• Removed Section: This view is also used to illustrate simple objects. However, to do this, the object is cut by a cutting plane line and a section is removed to illustrate another angle. Section (or hatching) lines help to enhance the clarity of the sectioned view and are conventionally drawn at 45° to the axis of the section. Dissimilar metals or adjacent parts of similar materials within the section are indicated by the hatching lines being drawn in different directions or with different spacing between the lines. The usual spacing between hatching lines is preferably not less than 4 mm, with the exception of small areas where they are usually not less than 1 mm apart.

FIGURE

• Complete Section: This view makes it easier to identify individual parts within an assembly (particularly where the assembly is more complex). Assemblies of multiple parts are often shown in complete or in half section views.

FIGURE

• Half Section: Sometimes it helps to be able to see the outside of the item being sectioned and, if the inside of the component is symmetrical, unnecessary detail can be omitted from the view. Both of these situations are overcome by half-sectioning the component.

FIGURE

If only the shape of a part needs to be shown, it is drawn with either a revolved or with a removed section. The symbols that are used for sectioning indicate where the object has been cut or sectioned and also indicate from whichever direction the section is to be viewed.