Engineering

Graphics

Course No. ME 193

Projections

of

SECTIONAL VIEWS

C O N T E N T S

2 . T Y P E S O F S E C T I O N I N G

3 . F U L L S E C T I O N A L V I E W S

4 . H A L F S E C T I O N A L V I E W S

5 . O F F S E T S E C T I O N A L V I E W S

6 . PA R T S N OT S E C T I O N E D

7 . H A T C H I N G

1 . S E C T I O N E D V I E W S

S E C T I O N E D V I E W S

The Internal details of c o m p l ex m a c h i n e p a r t s can shown

by c u t a w ay s e c t i o n s o r v i e w s

S E C T I O N A L V I E W S

• The external features of an object can be shown fully in Orthographic Views.

• However, the internal details can not be shown clearly by means of hidden lines.

• The Internal details of complex machine parts can shown by cut away sections or views

• The Internal details of complex machine parts can shown by cut away sections or views

S e c t i o n i n g P l a n e s

The Object is assumed to be cut by one or more Planes

usually parallel to the Principal Planes.

1. The Object is cut by a Planes parallel to the Vertical Plane.

2. The Object is cut by a Plane parallel to the Profile Plane.

3. The Object is cut by two orthogonal Planes ( parallel to V.P. & P.P. )

T Y P E S O F S E C T I O N S

1. Ful l Sect ional V iews

2 . Hal f Sect ional V iews

3 . Offset sect ional V iews

1. A cutting plane is assumed to be passed through the part.

3. The right half is imagined to be removed.

4. The interior details of the object now become visible.

2. The cutting plane cuts the part into two halves.

F U L L S E C T I O N A L V I E W S

F u l l S e c t i o n a l E N D V I E W

The interior details of the object become visible in

sectioned views.

F u l l s e c t i o n a l F R O N T V I E W

H A L F S E C T I O N A L V I E W S

• A Q u a r te r portion of the object is removed

( or H a l f of the view is sectioned )

H a l f S e c t i o n a l F R O N T V I E W

• Both the I nte r n a l and E x te r n a l details of the Object

can be shown simultaneously.

H a l f S e c t i o n a l E N D V I E W / T O P

V I E W

• Several features of an object that do not lie in a straight line,

• Such features can be shown by offsetting or bending the

cutting plane.

• The section is then called an OFFSET SECTION.

O F F S E T S e c t i o n a l V i e w s

• Views obtained by offsetting or bending the cutting plane.

are called an OFFSET SECTIONAL VIEWS.

C u t t i n g p l a n e L i n e s

• The cutting plane line is an imaginary line passing through

an object at the place where a section is to be made.

O f f s e t S e c t i o n s

• An Offset Sectioning Plane can have several bends.

O F F S E T S e c t i o n a l E l e v a t i o n

H AT C H I N G

• Material which has been cut by the cutting plane is

hatched.

• Dimensions are NOT inserted in hatched areas.

• Section lines on two adjacent parts should slope at 45º in

opposite directions.

• If there are more than two parts/materials , they ordinarily

cross-hatched at 30º and 60º.

P a r t s N o t S e c t i o n e d

1. When the cutting plane passes through

Thin features, such as RIB or a WEB,

Shafts, Keys & Splines,

Nuts, Bolts & Rivets.

2. S u c h Pa r t s are n o t s e c t i o n e d .

R i b s a n d W e b s

Hatching will give a false impression of solidity.

S u c h Pa r t s are therefore n o t s e c t i o n e d

N u t s B o l t s a n d S h a f t s

D i m e n s i o n i n g

• A dimensioned drawing should provide complete

information of the actual Machine Part.

• Dimension lines are continuous thin lines.

• Projection lines do not touch the object .

• Projection lines are drawn perpendicular to the object.

T y p e s o f D i m e n s i o n i n g

1. Parallel Dimensioning

The dimension lines should not cross the projection

lines.

2. C h a i n D i m e n s i o n i n g .

3. C o m b i n e d D i m e n s i o n i n g .

D i m e n s i o n i n g o f C i r c l e s & A r c s