sectional view.pdf

ME 121 – Engineering Drawing and Graphics (Spring 2013)

Sectional View


Motivation


Sectional View of Valves & Cylinder of 100 HP Engine

Motivation


Introduction

• A sectional view represents the part of an object which remains after a portion has been removed.

• Used to show hidden shape or form• Will help to clarify what would normally be shown as hidden

detail• Only solid material being cut is sectioned• The section is obtained by cutting the component into two

parts at some good points• Sectioning symbol or hatching should be used to indicate the

part that has been cut.


Types

• Longitudinal Section – Lengthwise

• Cross Section – cross wise

– FULL

– HALF (half way across a symmetric object)

– BROKEN (partial, when a full and half section is not needed)


How To?

Part is CUT with an imaginary plane.


How To?


How To? - Section Example

Notice how the cutting plane is indicated.

Notice how the cut material is shown.

Sectional view label


Lines Used in Section Views

• Cutting Plane Line: Used to show where the object is being cut.

– (Phantom line type)


How To? - Lines Used in Section Views

Shows where the part is being cut.

Arrows point to the portion being kept.

Section Lines


Lines Used in Section Views

• Section Lines: Section lines are used to indicate where the cutting plane cuts the material.

– Section lines are thin lines. – Section line symbols are chosen according to the material of

the object – Section lines are generally drawn at a 45 angle.


Introduction - Hatching

Thin continuous line. Drawn at 45° to the horizontal, in either the right or left direction.


Material Symbols

Figure 7.33 (ANSI Standard)Page 169


Adjacent Parts


How To? - Summary

• Section cutting planes are denoted by chain line• Arrowheads indicate the direction of viewing• The section view is identified by 'SECTION A-A'


How to? - Example.


Rules & Exceptions

As general rule, all material cut by a cutting plane is hatched,

except for

web, shafts, bolts, rivets, keys, pins, and similar parts


Rules of Sectioning

• Rule 1:A section lined area is always completely bounded by a visible outline.


Rules of Sectioning

• Rule 2:The section lines in all areas should be parallel.

– Section lines shown in opposite directions indicate a different part.


Rules of Sectioning

• Rule 3: All the visible edges behind the cutting plane should be shown.


Rules of Sectioning

• Rule 4:Hidden features should be omitted in all areas of a section view.

– Exceptions include threads and broken out sections.


Rules & Exceptions - Example


Rules & Exception - Example


Sectioning

Types of Sections


Types of Sections

• The type of section used depends on the situation and what information needs to be conveyed.

• Types of sections– Full Section– Half Section– Offset Section– etc …


Full Section


Full Section

• To create a full section, the cutting plane passes fully through the object.

– Used in many cases to avoid having to dimension hidden lines.


Exercise

• Given the top and right side views, sketch the front view as a full section.

– The material used is steel.


Fill in the visible lines in the front full sectional view


Fill in the section lines in the front full sectional view


Section lines are bounded by visible lines

Visible features behind the cutting plane are shown.


Orthogonal View of a Section


Isometric Full Section View Example


Half Section


Half Section

A half section exposes the

interior of one half of an object while retaining the exterior of the other half


Half Section

Half sections are used

mainly for symmetric objects or assembly drawings.


Half Section

• A centerline is used to separate the two halves.

• Hidden lines should not be shown on either half.


Exercise

• Given the front and right side views, sketch the top view as a full section and create a half sectioned front view.

– The material is brass.


Fill in the visible lines in the top full section view.


Fill in the section lines in the top full section view.


Fill in the visible lines in the right side half section view.


Fill in the section lines in the right side half section view.


No hidden lines

Center line divides the halves


Isometric Half Section View


Orthogonal Section View


Offset Section


Offset SectionAn offset section is produced by bending the cutting plane to show features that don’t lie in the same plane.


Offset Sectional ViewIsometric view of an offset section


Orthogonal View of an Offset Section


Exercise

• Given the front and top views, sketch the three missing section views in their appropriate places. The material is cast iron.

sectional view.pdf

Documents

orthogonal

sectional

side views

section view

section lines

offset section

visible lines

121 engineering