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3sectional projection (Engineering Graphics Drawing)

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Page 1: 3sectional projection (Engineering Graphics Drawing)

Section Views

Page 2: 3sectional projection (Engineering Graphics Drawing)

TOPICS

Introduction

Terminology & common practices

Kind of sections

Dimensioning

Page 3: 3sectional projection (Engineering Graphics Drawing)

Projection Systems

Page 4: 3sectional projection (Engineering Graphics Drawing)

Introduction

Page 5: 3sectional projection (Engineering Graphics Drawing)

ObjectObject

GRAPHICS COMMUNICATION WITH ENGINEERING DRAWING

WorkingdrawingWorkingdrawing

Clear ?

Orthographicprojection

(convention)

Section viewsconvention

Section Views

Orthographic Projection

Finish

Yes

No

Dimensioning

Page 6: 3sectional projection (Engineering Graphics Drawing)

PURPOSES OFSECTION VIEWS

Clarify the views by

Facilitate the dimensioning.

reducing or eliminating the hidden lines.

revealing the cross sectional’s shape.

Let See the example

Page 7: 3sectional projection (Engineering Graphics Drawing)

EXAMPLE : Advantage of using a section view.

Page 8: 3sectional projection (Engineering Graphics Drawing)

Terminology andcommon practices

Page 9: 3sectional projection (Engineering Graphics Drawing)

Cuttingplane

CUTTING PLANE

Cutting plane line

Cutting plane is a plane that imaginarily cuts

the object to reveal the internal features.

Section lines

Page 10: 3sectional projection (Engineering Graphics Drawing)

Cutting plane line is an edge view of the cutting

plane.

CUTTING PLANE LINE

Indicate the pathof cutting plane.

Page 11: 3sectional projection (Engineering Graphics Drawing)

ANSIstandard

Thick line

Thick line

JIS & ISOstandard

Thin line

CUTTING PLANE LINESTYLES

Viewingdirection

Viewingdirection

Viewingdirection

This course

Page 12: 3sectional projection (Engineering Graphics Drawing)

SECTION LINING

Section lines or cross-hatch lines are used to

indicate the surfaces that are cut by the cutting

plane.

Sectionlines

Drawn with 4H pencil.

Page 13: 3sectional projection (Engineering Graphics Drawing)

SECTION LINES SYMBOLS

The section lines are different for each of

material’s type.

Cast iron,Malleable iron

Steel Concrete Sand Wood

For practical purpose, the cast iron symbol is

used most often for any materials.

Page 14: 3sectional projection (Engineering Graphics Drawing)

Hatch Patterns

Page 15: 3sectional projection (Engineering Graphics Drawing)

SECTION LINING PRACTICE

The spaces between lines may vary from 1.5 mm

for small sections to 3 mm for large sections.

COMMON MISTAKE

Page 16: 3sectional projection (Engineering Graphics Drawing)

SECTION LINING PRACTICE

It should not be drawn parallel or perpendicular

to contour of the view.

COMMON MISTAKE

Page 17: 3sectional projection (Engineering Graphics Drawing)

Kinds of Sections

Page 18: 3sectional projection (Engineering Graphics Drawing)

KIND OF SECTIONS

1. Full section

2. Offset section

3. Half section

4. Broken-out section

5. Revolved section (aligned section)

6. Removed section (detailed section)

7. Aligned Section

Page 19: 3sectional projection (Engineering Graphics Drawing)

FULL SECTION VIEW

The view is made by passing the straight cutting

plane completely through the part.

Page 20: 3sectional projection (Engineering Graphics Drawing)

OFFSET SECTION VIEWThe view is made by passing the bended cutting

plane completely through the part.

Do not show the edge viewsof the cutting plane.

Page 21: 3sectional projection (Engineering Graphics Drawing)

TREATMENT OF HIDDEN LINES

Hidden lines are normally omitted from section

views.

Page 22: 3sectional projection (Engineering Graphics Drawing)

HALF SECTION VIEWThe view is made by passing the cutting plane halfway

through an object and remove a quarter of it.

Page 23: 3sectional projection (Engineering Graphics Drawing)

HALF SECTION VIEW

A center line is used to separate the sectioned half

from the unsectioned half of the view.

Hidden line is omitted in unsection half of the view.

Page 24: 3sectional projection (Engineering Graphics Drawing)

The view is made by passing the cutting plane normal

to the viewing direction and removing the portion of an

object in front of it.

BROKEN-OUT SECTION VIEW

Page 25: 3sectional projection (Engineering Graphics Drawing)

A break line is used to separate

the sectioned portion from the

unsectioned portion of the view.

BROKEN-OUT SECTION VIEW

There is no cutting plane line.

Break line is a thin continuous

line (4H) and is drawn freehand.

Page 26: 3sectional projection (Engineering Graphics Drawing)

EXAMPLE : Comparison among several section techniques

Page 27: 3sectional projection (Engineering Graphics Drawing)

Revolved sections show cross-sectional features of a part.

No need for additional orthographic views.

This section is especially helpful when a cross-section varies.

REVOLVED SECTION VIEW

Page 28: 3sectional projection (Engineering Graphics Drawing)

REVOLVED SECTION VIEW

Basic concept

Page 29: 3sectional projection (Engineering Graphics Drawing)

REVOLVED SECTION VIEW

Basic concept

Page 30: 3sectional projection (Engineering Graphics Drawing)

Given

Step 1

a. Assign position of cutting plane.

b. Draw axis of rotation in front view.

Steps in construction

REVOLVED SECTION VIEW

Edge view of Edge view of cross-sectioncross-section

Page 31: 3sectional projection (Engineering Graphics Drawing)

Steps in construction

Given

a. Transfer the depth dimension to

the front view.

REVOLVED SECTION VIEW

Step 2

Page 32: 3sectional projection (Engineering Graphics Drawing)

Steps in construction

Given

REVOLVED SECTION VIEW

a. Draw the revolved section.

Step 3

b. Add section lines.

Page 33: 3sectional projection (Engineering Graphics Drawing)

Steps in construction

Given

REVOLVED SECTION VIEW

FINAL PICTURE

Page 34: 3sectional projection (Engineering Graphics Drawing)

Placement of revolved section

1. Superimposed to orthographic view.

SuperimposedBreak

2. Break from orthographic view.

REVOLVED SECTION VIEW

Page 35: 3sectional projection (Engineering Graphics Drawing)

6. Removed section

Removed section is revolved section.

Used where space does not enough for revolved section

Can be located elsewhere on a drawing with properly labeled

REMOVED SECTION VIEW

Section view is shown outside the view.

Page 36: 3sectional projection (Engineering Graphics Drawing)

Example : Revolved vs. removed sections.

Revolved section Removed section

REMOVED SECTION VIEW

Page 37: 3sectional projection (Engineering Graphics Drawing)

Example : Situation that removed section is preferred.REMOVED SECTION VIEW

PreferredPoor

Too messy !!

Page 38: 3sectional projection (Engineering Graphics Drawing)

Example : Multiple removed section viewsREMOVED SECTION VIEW

A

A

B

B

SECTION A – A

SECTION B – B

Page 39: 3sectional projection (Engineering Graphics Drawing)

Aligned Sections

Aligned sections use an angled cutting plane to pass through angled features. The plane and feature are then imagined to be revolved into the original plane and the section projected from there

Page 40: 3sectional projection (Engineering Graphics Drawing)

Aligned Sections

Page 41: 3sectional projection (Engineering Graphics Drawing)

Dimensioningin Section View

Page 42: 3sectional projection (Engineering Graphics Drawing)

In most cases, dimensioning of the section views

follows the typical rules of dimensioning.

GOODPOOR

Page 43: 3sectional projection (Engineering Graphics Drawing)

GOODPOOR

50

10

50

10

DIMENSIONING

Page 44: 3sectional projection (Engineering Graphics Drawing)

For a half-section view,

use dimension line with

only one arrowhead that

points to the position inside

the sectioned portion.

50

DIMENSIONING

Page 45: 3sectional projection (Engineering Graphics Drawing)

PARTS IN WHICH SECTIONS ARE NOT TO BE SHOWN