SECTIONAL VIEWS

LECTURE 5

Background:

• Initially, it has been studied that internal hidden details of the object are shown in

orthographic views by dashed lines.

• The intensity of the dashed lines depends on the complexity of internal structure of the

object.

• It will become more difficult to visualize the shape of the object as the number of

dashed lines go increasing.

Do you know what is inside it

• Insert an imaginary plane inside the object to get a view of it.

Sectional View:

• The part of the object between the observer and the cutting plane is assumed to be

removed.

• The cut view thus obtained is called the SECTIONAL VIEW.

•

Cutting Plane Line:

• In an isometric view, a sectional plane (Cutting plane) line is indicated by Phantom

Line.

Types of Cutting Planes:Vertical Section Plane Cutting plane parallel to vertical plane

Horizontal Section Plane Cutting plane parallel to horizontal plane

Profile Section Plane Cutting plane parallel to profile plane

Auxiliary Section Plane Cutting plane inclined to either horizontal or

vertical plane.

1. Auxiliary Inclined Plane:A plane inclined to horizontal plane and

perpendicular to vertical plane.

2. Auxiliary Vertical Plane:A plane inclined to vertical plane and

perpendicular to horizontal plane

Oblique Section Plane Cutting plane inclined to both horizontal and

vertical plane

Hatching of Sections:

• The surface created by cutting the object by a section plane is called a “ Section”.

• Sections are indicated by drawing the hatching or section lines.

• These lines are continuous and drawn at the angle of 45° to the principle outlines or the

lines of symmetry of the section.

• The spacing should be uniform and in proportion to the size of the section.

45°

Section Line:

Section Lines for Different Materials:

5 Minutes Exercise:

• Mark the angles.

Types of Sectional Views:

• Sectional Front View:

When an object is cut by a vertical

cutting plane or Auxiliary Vertical

Plane, the front view obtained is

called the Sectional Front View.

• Sectional Top View:

When an object is cut by a

horizontal cutting plane or

Auxiliary Inclined Plane, the top

view obtained is called the

Sectional Top View.

• Sectional Side View:

When an object is cut by a profile

cutting plane or Auxiliary Vertical

Plane or Auxiliary Inclined Plane,

the front view obtained is called

the Sectional Side View.

Methods of Sectioning

• Full Section

• Half Section

• Offset Section

• Revolved Section

• Removed Section

• Aligned Section

Full Section

• The sectional view obtained after removing the half portion of an object through its

centre.

Half Section

• The sectional view obtained by removing the quarter portion by means of two cutting

planes at right angles to each other.

Offset Section

• The sectional view obtained by a cutting plane in a zig-zag way so as to reveal the

maximum details of the object.

Revolved Section

• A revolved section is used to show the

uniform shape of the object from end

to end.

Removed Section

• Removed section is used to show the

variable shape of the object from end

to end.

Aligned Section

• An aligned section is used to show the

shape of features that do not align with

the vertical and horizontal centerlines

of the object.

Class Task:

• Draw a full sectional view

of the CAD Model with

respect to Vertical

Section Plane.