This document discusses different types of section views including full sections, half sections, broken-out sections, removed sections, and offset sections. It addresses the proper placement of cutting planes and section lines, as well as common mistakes to avoid when creating section views. The purpose of section views is to reveal interior or hidden areas of an object by removing part of the material.

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SECTIONING
Name of the Faculty: Shivraj Puggal
UID: 16125
E-mail ID:shivraj.16125@lpu.co.in

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Issues to be addressed in the unit
• Types Sectional views
a) Full section
b) Half section
• Placement of Section Views
• Section Lining – Line Placement
• Section Line Mistakes
• Section Line Technique

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What is a “Section View” ?
• A section view is a view used on a drawing to
show an area or hidden part of an object by
cutting away or removing some of that object.
• The cut line is called a “cutting plane”, and can
be done in several ways.
• The following slides will help show the several
methods or types of “section views”

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Section Views
Often there is a need to show interiors that cannot be illustrated clearly by
hidden lines. Interiors are shown by slicing through the object resulting in
cutaway view of the part. Cutaway views are called sectional views, cross
sections, or simply sections.

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Full Section
• In a full section, the cutting plane line
passes fully through the part.
• Normally a view is replaced with the full
section view.
• The section-lined areas are those portions
that have been in actual contact with the
cutting-plane.

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Cutting Plane

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Full Section

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Replacing the view

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Half Section
• Half Section is used to the exterior and
interior of the part in the same view.
• The cutting-plane line cuts halfway
through the part and removes one quarter
of the material.
• The line that separates the different types
(interior and exterior) may be a centerline
or a visible line.

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Half Sections
• In general:
– Omit hidden lines from both halves of a half
section whenever possible
– Use a center line to divide the sectioned half
and the unsectioned half

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Half Section

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Placement of Section Views
• Section views can replace the normal top,
front, side, or other standard orthographic
view

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Placement of Section Views

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Section Lining – Line Placement
• Lines should never be parallel or
perpendicular to the object lines.
• If the outline of the object has 45 degree
lines, 30 or 60 degree lines should be
used.
• Assemblies with several parts should be
lined with varying angle section lines.

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Section Lining – Line Placement

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Section Line Mistakes

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Section Line Mistakes

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Cutting Plane Line Style
• Cutting lines are thick lines (0.7 mm)
• The preferred cutting plane line style is
made up of equal dashes ending in
arrowheads
– Another style uses alternating long dashes
and pairs of short dashes

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Section Line Technique
• Uniformly spaced by
an interval of about .
10”
• Uniformly thin, not
varying thickness
• Do not run beyond
outer edges of the
visible lines
• Usually at 45˚ angle

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Section Line Technique

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Broken-Out Sections:
Often only a partial section of a view is needed to expose interior
shapes. Such a section, limited by an irregular break line is called a
broken-out section.

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Revolved Sections:
The shape of a cross section of an object may be shown in the
longitudinal view by means of a revolved section.
Revolved sections are made by assuming a plane perpendicular to the
center line or axis of the object and then revolving the plane 90
degrees about a center line at right angles to the axis.

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Removed
Sections:
A removed section is a
section view that is not
in direct projection
from the view
containing the cutting
plane.
Removed sections
should be labeled
Section A-A and
Section B-B,
corresponding to the
letters at the ends of
the cutting-plane line.
Removed sections
should be arranged in
alphabetical order from
left to right on the
drawing sheet

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Offset Sections:
In sectioning through an irregular object it is often desirable to show
features that do not lie in a straight line by offsetting or bending the
cutting plane. Such a section is called an offset section.
The offsets or bends in the cutting plane are all 90 degrees and are
never shown in the section view.

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Ribs in Sections:
To avoid a false impression
of thickness and solidity,
ribs, webs, gear teeth, and
other similar flat features are
not section lined even
though the cutting plane
passes through the feature.
In the example the cutting
plane A-A passes through
the vertical rib or web but
the rib or web is not section
lined (figure a).
Figure (b) is incorrect
because it gives a false
impression of thickness or
solidity.

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Aligned Sections:
To include in a section view
certain angled elements, the
cutting plane may be bent to
pass through those features.
The plane and features are
imagined to be revolved into
the original plane.
In the example the cutting
plane is bent to pass through
the angled arm and then
revolved to a vertical position
(aligned) from where it is
projected across to the
section view.

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