Chapter 4Chapter 4S ti ViSection Views

TOPICS

IntroductionIntroduction

Terminology & common practicesgy p

Kind of sectionsKind of sections

Dimensioningg

IntroductionIntroduction

GRAPHICS COMMUNICATION WITH ENGINEERING DRAWING

Object

WITH ENGINEERING DRAWINGOrthographicOrthographic

Projection

Dimensioning

Workingdrawing Orthographicg Orthographic

projection(convention)

NoClear ?

Section views

Section Views

Yes

No

conventionFinish

PURPOSES OFSECTION VIEWSSECTION VIEWS

Clarify the views byClarify the views by

reducing or eliminating the hidden lines.g g

revealing the cross sectional’s shape.

Facilitate the dimensioning.

Let See the exampleLet See the example

EXAMPLE : Advantage of using a section view.

T i l dTerminology andticommon practices

CUTTING PLANE

Cutting plane is a plane that imaginarily cutsth bj t t l th i t l f tthe object to reveal the internal features.

Cuttingplane Cutting plane line

Section lines

CUTTING PLANE LINECutting plane line is an edge view of the cutting plane.plane.

Indicate the pathof cutting plane.

CUTTING PLANE LINESTYLES

ANSI

Thick line

ANSIstandard

Thick line

Viewingdirection

Viewingdirection

JIS & ISOstandard

Thin linestandard

Viewingdi ti

This coursedirection

SECTION LININGSection lines or cross-hatch lines are used toindicate the surfaces that are cut by the cuttingindicate the surfaces that are cut by the cuttingplane.

SectionSectionlines

Drawn with 4H pencil.p

SECTION LINES SYMBOLSThe section lines are different for each of material’s typematerial’s type.

For practical purpose, the cast iron symbol is used most often for any materials.

Cast iron,Malleable iron

Steel Concrete Sand Wood

SECTION LINING PRACTICEThe spaces between lines may vary from 1.5 mmfor small sections to 3 mm for large sectionsfor small sections to 3 mm for large sections.

COMMON MISTAKECOMMON MISTAKE

SECTION LINING PRACTICEIt should not be drawn parallel or perpendicularto contour of the viewto contour of the view.

COMMON MISTAKECOMMON MISTAKE

Kinds of SectionsKinds of Sections

KIND OF SECTIONS

1. Full section

2. Offset section

3. Half section

4 B k t ti4. Broken-out section

5 Revolved section (aligned section)5. Revolved section (aligned section)

6. Removed section (detailed section)

FULL SECTION VIEWThe view is made by passing the straight cutting plane completely through the part.p p y g p

OFFSET SECTION VIEWThe view is made by passing the bended cutting plane completely through the part.y g

Do not show the edge viewsof the cutting plane.

TREATMENT OF HIDDEN LINESHidden lines are normally omitted from sectionviewsviews.

HALF SECTION VIEWThe view is made by passing the cutting plane halfwaythrough an object and remove a quarter of it.

HALF SECTION VIEWA 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.

BROKEN-OUT SECTION VIEWThe 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

A break line is used to separate the sectioned portion from the unsectioned portion of the view.u sect o ed po t o o t e e

Break line is a thin continuous line (4H) and is drawn freehand.

There is no cutting plane line.

EXAMPLE : Comparison among several section techniques

REVOLVED SECTION VIEW

Revolved sections show cross-sectionalRevolved sections show cross sectional features of a part.

No need for additional orthographic views.

This section is especially helpful when across-section varies.

REVOLVED SECTION VIEWBasic concept

REVOLVED SECTION VIEWBasic concept

REVOLVED SECTION VIEW

Given

Steps in construction

Edge view of Edge view of crosscross--sectionsection

Step 1a. Assign position of cutting plane.a. Assign position of cutting plane.b. Draw axis of rotation in front view.

REVOLVED SECTION VIEWSteps in construction

Given

a. Transfer the depth dimension to Step 2

pthe front view.

REVOLVED SECTION VIEWSteps in construction

Given

a. Draw the revolved section.Step 3

b. Add section lines.

REVOLVED SECTION VIEWSteps in construction

Given

FINAL PICTUREFINAL PICTURE

REVOLVED SECTION VIEWPlacement of revolved section

1 Superimposed to orthographic view1. Superimposed to orthographic view.

2. Break from orthographic view.

SuperimposedBreak SuperimposedBreak

6 Removed sectionREMOVED SECTION VIEW

6. Removed sectionRemoved section is revolved section.

Section view is shown outside the view.

Used where space does not enough for revolved section

C b l t d l h d iCan be located elsewhere on a drawing with properly labeled

Example : Revolved vs. removed sections.REMOVED SECTION VIEWRevolved section Removed section

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

Too messy !!

Example : Multiple removed section viewsREMOVED SECTION VIEW

A B

B

A

S C O

SECTION A – A

SECTION B – B

Dimensioningin Section View

In most cases, dimensioning of the section viewsfollows the typical rules of dimensioning.

GOODPOOR

DIMENSIONINGGOODPOOR

10 10

50 50

DIMENSIONING

For a half-section view,use dimension line withonly one arrowhead thatpoints to the position insidepoints to the position insidethe sectioned portion.

50