Year 11/12 Industrial Graphics sectional view PowerPoint

1. Sectional Standards and
Conventions

3. Answers
A 35 mm
B 46 mm
C 32 mm
D 11 mm
E 15 mm
H 49 mm
J 11 mm

4. SectionalViews
• The main purpose of a sectional view is to effectively communicate internal
information to enhance the viewer’s understanding of the part.
• There are several different types of section views that engineers use to
communicate internal geometry.
• Full sectional view
• Half sectional view
• Offset sectional view

5. Hidden Detail
• Sometimes an object features detail that are internal and cannot be
seen by viewing external surfaces.
• In these circumstances, orthographic drawing is vital in depicting
otherwise hidden detail.
• Hidden detail may appear on any of the featured views.

6. Hidden Detail
• Hidden details are indicted by a thin broken line. It is essential
that this line convention be followed so that the detail is clearly
understood and not mistaken for an outline.

8. Cross-sections
• The cross-sectioning of an object allows for the internal details to be clearly
shown.
• A cross-section is literally a ‘cut-through’ view of an object.

9. Cross-sections
An imaginary cut is
made at an appropriate
point to display the
relevant information.

10. The cutting plane
• The path of the imaginary cut is indicated on the orthographical drawing by
a cutting plane.
• The cutting plane is shown as a broken line with thick lines at each end.
• Narrow arrowheads touch the end of the cutting plane, indicating the
direction of the cut and the subsequent direction of view.

11. The cutting plane
The first cross-section is always
labelled Section A-A, subsequent
sections are B-B, C-C and so on.

12. Crosshatching
• In order to show solid areas of
the object that have been ‘cut’,
hatching is used
• The hatching should be drawn
at 45° and be suitably spaced
relative to the area covered.

13. Crosshatching
• Where adjacent parts of an object meet, the direction of hatching should be
reversed.

14. Full sectional view
• A full section view is created by running the cutting plane through the entire
length of the object being sectioned
• The cutting plane may be identified and indicated in the usual manner to
increase clarity.

16. Half sectional views
• A symmetrical object or assembly may be drawn as a half section, showing
one half up to the centre line in section and the other half in full view
• The cutting plane effectively removes a quarter of the object
• A normal centreline is listed on the section view.The wording, half section,
can be confusing because one thinks of showing half the part.
• Remember, a half section shows one-fourth of the part, not one half!

17. Half sectional views

18. Offset sectional view
• In order to include features that are not in a straight line, the cutting-plane
line may be offset or bent, so as to include several planes or curved surfaces
• An offset section is similar to a full section in that the cutting plane extends
through the object from one side to the other.
• The change in direction of the cutting-plane line is not shown on the
sectional view.

19. Offset sectional views

20. Rules to remember
• A sectional view shows the part of the component in front of the sectional
plane arrows
• Only the material which has been cut by the sectioning plane is cross-
hatched
• A sectional view must not have any full lines drawn over cross-hatched areas
• Dimensions are not inserted in cross-hatched sectioned areas