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• Muhammad Saqib Swati

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Lec_01_Introduction.pdf Lec_2_TOP1.pptx Lec_3_TOP2.pptx Lec_04_Points and Lines.pptx Lec_05_Dimensioning.pptx Lec_06_Sectioning.pptx Lec_08_Ortho Reading Writing.pptx Lec_10_Engineering Curves.pptx Lec_11_Develpment of Surrfaces.pptx Lec_12_Joining of Materials.pptx Lec_13_Geometric Tolerancing (1).pptx Lec_14_Production_Drawing_2.pptx Lec_15_Assembly_Drawing.pptx

ME-102 Engineering Graphics Lecture 1

Introduction

Course Instructor:

Aaqib Ali Research Associate Office # G-07 – FME Office Ext. 2368

Outcome Based Education (OBE) • System of education that revolves around goals (outcomes) the students are to achieve through a degree program.

Outcome Based Education (OBE) Institute Vision/Mission

Faculty Vision/Mission

Program Eductional Objectives (PEO's)

Program Learning Outcomes (PLO's)

Course Learning Outcome (CLO1)

Course Learning Outcome (CLO2)

Course Learning Outcome (CLO3)

Course Learning Outcome (CLO4)

Course Learning Outcomes Sr. No

Course Learning Outcomes

PLOs

Blooms Taxonomy

CLO_1

Students will demonstrate the basic understanding of engineering graphics

PLO1

C2

CLO_2

Student will be able to communicate, represent and document the design ideas.

PLO10

A4

CLO_3

Students will be able to use modern CAD tools to basic design levels

PLO5

P2

Course Learning Outcomes • The CLO’s are mapped to PLO’s and are evaluated at the end of each course. • You need to achieve at least 40% of each PLO. • If you fail to achieve at least 40% in any of the 12 PLO’s at the end of your 4 year program, necessary action may be taken against you. • PLO’s, PEO’s and vision/mission of faculty and institute are available on the GIKI web site

Text Book and Other Resources • Text Book: Technical Graphics Communication 3rd edition by Eric N. Wiebe and Garry R. Bertoline (Soft copy be made available through e-mail/portal)

• Lectures, E-Books and other Self Study Material (Will be shared through e-mail/portal)

Please reach in class at least 5 minutes earlier. Door will be locked after 5 minutes.

Grading Policy (Subject to Change) • Quizzes

= 10%

(2 Mega Quizzes)

• Assignments

= 5%

(At least 3)

• Lab

= 40%

• Mid Exam

= 15%

• Final Exam

= 30%

Please note that you have to score a minimum of 35 to pass the course (FME Policy)

What is Engineering Design??

Typical Engineering Design Cycle Problem Identification

Preliminary Ideas

Design Refinement

Analysis

Optimization Documentation

Graphics in Design Process Technical graphics is a real and complete language used in the design process for:

1. Visualization 2. Communication 3. Documentation

Visualization • Visualization is the ability to mentally picture things that are not there. • Ability to visualize problem solutions and communicate them through sketches is one of the most important skill of a designer.

Communication • Refinement of your initial sketches so that your design solution can be communicated to others without ambiguity. • Usually done by creating a three dimensional (3D) model

Documentation • Is a process to permanently record that solution/Final sketch/Design.

• 2D drawing follow strict standard practices. These standards are the language used to communicate graphically. • 3D graphical representation can also be part of the final documentation

Engineering Graphics It refers basically to the use of Drawings/Sketches to represent design ideas, configurations & specifications and analysis for an engineering project.

Effectiveness of Graphics Language 1. Try to write a description of this object. 2. Test your written description by having someone attempt to make a sketch from your description.

You can easily understand that …

The word languages are inadequate for describing the size, shape and features completely as well as concisely.

Composition of Graphic Language Graphic language in “engineering application” uses lines to represent the surfaces, edges and contours

of objects. The language is known as “drawing” or “drafting” . A drawing can be done using freehand, instruments or computer methods.

Freehand drawing The lines are sketched without using instruments other than pencils and erasers.

Example

Instrument drawing Instruments are used to draw straight lines, circles, and curves concisely and accurately. Thus, the drawings are usually made to scale.

Example

Computer Aided drawing The drawings are usually made by commercial software such as AutoCAD, Pro-E/ CREO, solid works etc.

Example

Engineering Drawing • An engineering drawing is a set of drawings/Views/Sections etc. that communicates an idea, design, schematic or model. • Engineering drawing is an universal graphic language, known as the language of engineers. • It is used by engineers to develop and record their ideas and transmit them to others for execution. Different types of drawing For e.g. mechanical engineers need productions drawing to manufacture a component or assembly.

Elements of Engineering Drawing Engineering drawing are made up of graphics language and word language.

Graphics language Describe a shape/geometry (mainly).

Word language Describe size, location and specification of the object.

Drawing Standards Standards are set of rules that govern how technical drawings are represented.

Drawing standards are used so that drawings convey the same meaning to everyone who reads them.

Standard Code Full name

Country

Code

Turkey

TS

USA

ANSI

American National Standard Institute

Japan

JIS

Japanese Industrial Standard

UK

BS

British Standard

Australia

AS

Australian Standard

Germany

DIN

Deutsches Institut für Normung

ISO

International Standards Organization

Turkish Standard

Drawing Sheet Trimmed paper of a size A0 ~ A4.

A4

A3

Standard sheet size (ISO)

A4 A3 A2 A1 A0

210 x 297 297 x 420 420 x 594 594 x 841 841 x 1189

(Dimensions in millimeters)

A2

A1

A0

Orientation of drawing sheet 1. Type X (A0~A4)

c

2. Type Y (A4 only) d

d

Drawing space

Border lines

c

c

Title block

Sheet size A4 A3 A2 A1 A0

c (min) d (min) 10 25 10 25 10 25 20 25 20 25

Drawing space

Title block

Drawing Scales Length, size

Scale is the ratio of the linear dimension of an element of an object shown in the drawing to the real linear dimension of the same element of the object. Size in drawing

Actual size

:

Drawing Scales Designation of a scale consists of the word “SCALE” followed by the indication of its ratio, as follow SCALE 1:1

for full size

SCALE X:1 for enlargement scales (X > 1) SCALE 1:X for reduction scales

(X > 1)

Dimension numbers shown in the drawing are correspond

to “true size” of the object and they are independent of the scale used in creating that drawing.

Basic Line Types Types of Lines

Appearance

Name according to application

Continuous thick line

Visible line

Continuous thin line

Dimension line Extension line

Leader line Dash thick line

Hidden line

Chain thin line

Center line

NOTE : We will learn other types of line in later chapters.

Meaning of Lines Visible lines represent features that can be seen in the

current view Hidden lines represent features that can not be seen in the current view Center line

represents symmetry, path of motion, centers of circles, axis of axisymmetrical parts

Dimension and Extension lines indicate the sizes and

location of features on a drawing

Example : Line conventions in engineering drawing

DRAWING TOOLS

Drawing Boards

DRAWING TOOLS

1. T-Square

2. Triangles

DRAWING TOOLS

2H or HB for thick line 4H for thin line

3. Adhesive Tape

4. Pencils

DRAWING TOOLS

5. Sandpaper

6. Compass

DRAWING TOOLS

7. Pencil Eraser 8. Circular Template 10. Sharpener

DRAWING TOOLS

11. Scales

Sketching Techniques

Self study • • • •

Engineering Drawing rules Freehand sketching Line types Lettering

• Student’s should contact Teaching Assistants/Lab Engineers incase of any problem. • If not solved • Office hours (14:30 ~ 16:30 HRS) Monday ~ Thursday

End of Lecture 1 Thank you…

ME-102

Engineering Graphics Lecture #: 2

Projection Theory (Part: One)

Faculty of Mechanical Engineering Ghulam Ishaq Khan Institute of Engineering Sciences & Technology

PROJECTION METHOD

Perspective

Parallel

Oblique

Axonometric

Orthographic

Multiview 2

PROJECTION THEORY The projection theory is used to graphically represent 3-D objects on 2-D media (paper, computer screen).

The projection theory is based on two variables: 1) Line of sight 2) Plane of projection (image plane or picture plane)

3

OBJECT FEATURES Edges

are lines that represent the boundary between two faces.

Corners

Represent the intersection of two or more edges. Edge

Corner

Edge

No corner

No edge

No corner

OBJECT FEATURES Surfaces

are areas that are bounded by edges or limiting element.

Limiting element

is a line that represents the last visible

part of the curve surface.

Surface

Surface

Limit

Surface

Limit

Line of sight

is an imaginary ray of light between an

observer’s eye and an object.(projectors) There are 2 types of LOS : parallel and converge

Parallel projection

Perspective projection

Line of sight Line of sight

6

Plane of projection is an imaginary flat plane which the image is created. The image is produced by connecting the points where the LOS pierce the projection plane. Parallel projection

Perspective projection

Plane of projection

Plane of projection

7

Orthographic projection is a parallel projection technique in which the parallel lines of sight are perpendicular to the projection plane

Object views from top

1

2

1

5

2

3

4

5 3

4 Projection plane

8

ORTHOGRAPHIC VIEW Orthographic view depends on relative position of the object to the line of sight. Rotate

Two dimensions of an object is shown.

Tilt

More than one view is needed to represent the object.

Multiview drawing Three dimensions of an object is shown. Axonometric drawing 9

ORTHOGRAPHIC VIEW NOTES Orthographic projection technique can produce either 1. Multiview drawing : that each view show an object in two dimensions. 2. Axonometric drawing : that show all three dimensions of an object in one view. Both drawing types are used in technical drawing for

communication.

10

Axonometric (Isometric) Drawing Advantage

Easy to understand

Disadvantage Shape and angle distortion Example

Distortions of shape and size in isometric drawing

Circular hole becomes ellipse.

Right angle becomes obtuse angle. 11

Multiview Drawing Advantage

It represents accurate shape and size.

Disadvantage Example

Require practice in writing and reading.

Multiviews drawing (2-view drawing)

12

MULTIVIEW PROJECTION … can be presented only two in each view.

Width

Depth

Height

Height

Adjacent view(s) is needed to fulfill the size description.

Depth

Three principle dimensions of an object …

Width

Depth

13

TO OBTAIN MULTIVIEW REPRESENTATION OF AN OBJECT 1. Revolve the object with respect to observer. 2. The observer move around the

object. 14

REVOLVE THE OBJECT

Top view

Front view

Right side view

15

OBSERVER MOVE AROUND Top view

Front view

Right side view

16

THE GLASS BOX CONCEPT

Rear view

Left side view

Bottom view

17

Depth

History

Width Height

18

Six Principal View (Object in Glass Box)

Page 19 of 30

Six Principal Views Six principal views produced by mutually perpendicular planes of projection.

Page 20 of 30

PROJECTION SYSTEMS 1. First angle system - European country - ISO standard

First Quadrant

2. Third angle system - Canada, USA, Japan, Mostly In PAK

Third Quadrant

ORTHOGRAPHIC PROJECTION 1st angle system

3rd angle system

ORTHOGRAPHIC VIEWS 3rd angle system

1st angle system Folding line

Folding line Folding line

Folding line

ORTHOGRAPHIC VIEWS 1st angle system Right Side View

Front View

Top View

3rd angle system Top View

Front View Right Side View

PROJECTION SYMBOLS First angle system

Third angle system

How to make an Orthogonal Multi-View Drawing

1. Draw the front view. 2. Then project the view vertically to form the top view. 3. Project lines from the top and front views to make the side view. You need to construct a 45 degree line to achieve this.

End of Lecture 2 Thank you….

27

ME-102

Engineering Graphics Lecture #: 3

Projection Theory (Part: Two)

Faculty of Mechanical Engineering Ghulam Ishaq Khan Institute of Engineering Sciences & Technology

PROJECTION METHOD

Perspective

Parallel

Oblique

Axonometric

Orthographic

Multiview

Perspective Projection • Perspective projection mimic what the human eye sees. • Requires that the object be positioned at finite distance and viewed from a single point (SP: Station Point) •

Projectors are not parallel.

•

Image formed is always shorter/larger than the actual dimension of the object.

•

Are somewhat difficult to create.

Disadvantage of Perspective Projection Perspective projection is not used by engineer for manufacturing of parts, because: 1) It is difficult to create. 2) It does not reveal exact shape and size.

Width is distorted

One, Two & Three Point Perspective Projection

One, Two & Three Point Perspective Projection

One, Two & Three Point Perspective Projection

Axonometric Projection Parallel & normal to picture plane B

A

Line of sight

D A C

B D

C

Axonometric Projection Type of axonometric drawing Axonometric axis

a

1. Isometric

A

b

All angles are equal.

c

B B

Axonometric axis

a AC

D D

2. Dimetric

Two angles are equal.

c

b

C

Axonometric axis

a

3. Trimetric

b

c

None of angles are equal.

Isometric Drawing Isometric drawing is a drawing drawn on an isometric axes using full scale. Isometric projection

Isometric drawing

(True projection)

(Full scale)

Forshorten Full scale

Positions of Isometric Axes Isometric axes can be arbitrarily positioned to create

different views of a single object. Regular isometric

View point is looking down on the top of the object.

Reverse axis isometric

View point is looking up on the bottom of the object.

Long axis isometric

View point is looking from the right (or left) of the object.

Distance in Isometric Drawing True-length distances are shown along isometric lines. Isometric line is the line that run parallel to any of the isometric axes. Nonisometric lines

Isometric axes

Sketch from an actual object 1. Place the object in the position which its shape

and features are clearly seen. 2. Define an isometric axis. 3. Sketching the enclosing box. 4. Estimate the size an and relationship of each details. 5. Darken all visible lines.

Sketch from an actual object STEPS

1. Positioning object. 2. Select isometric axis. 3. Sketch enclosing box.

4. Add details. 5. Darken visible lines.

Sketch from an actual object STEPS 1. Positioning object. 2. Select isometric axis.

3. Sketch enclosing box. 4. Add details. 5. Darken visible lines. Note

In isometric sketch/drawing), hidden lines are omitted unless they are absolutely necessary to completely describe the object.

Sketch from multiview drawing 1. Interprete the meaning of lines/areas in

multiview drawing. 2. Locate the lines or surfaces relative to isometric

axis.

Example 1 : Object has only normal surfaces

Top Regular H

Top View

Front

Side

W

W

Bottom View

H

Front View

D

Side View D

Reverse

Side

Front

Bottom

D

Example 2 : Object has inclined surfaces

Nonisometric line

y

H

y

x

Front View

x W

Example 3 : Object has inclined surfaces x C

B

A

x

x

x

B A

y

C

y C

B

Nonisometric line

A

Oblique Projection Parallel & oblique to picture plane

A

Line of sight

A B

B C

C D

D

Oblique Projection • • • •

Is the basis for oblique drawing and sketching. Form of parallel projection, projectors are parallel to each other. Projectors are not perpendicular to the plane of projection. One face of an object is parallel to the plane of projection.

Oblique Projection Oblique drawing angle

30o

A

60o

45o

B C A

Type of Oblique drawing

B D

C

2) Cabinet

1) Cavalier

D

Full scale

45o

Half scale 45o

Oblique Drawings Place complex features (arc, hole, irregular shape surface parallel to frontal plane.

Orientation Guidelines

Object Orientation Guidelines The longest dimension of an object should be parallel to the frontal plane.

GOOD

WORSE

GOOD

WORSE

Object Orientation Guidelines Which orientation is better ?

Sketch from actual object

ESTIMATE DEPTH

ESTIMATE LINES

D

45

Sketch from multiview drawing

Sketch from multiview drawing

ASSIGNMENT #1 Draw two isometric drawing (both on single page) of a cube with length of each side =40mm & 50mm. Draw inscribed circles on each of the expose faces of the cubes (As in Fig) Instructions:

Draw on A4 paper, in portrait layout with Margins & Title Box as demonstrated. Draw circles as per Hints on next slide SUBMIT IN THE NEXT CLASS No assignments to TA’s or my office Acceptable.

Late submissions = ZERO

Hints for Inscribed circles

Cube 1 (40mm)

Cube 2 (50mm)

Thank you…. End of Lecture 3

ME-102

Engineering Graphics Lecture #: 4

Projection of Points

and Lines Faculty of Mechanical Engineering Ghulam Ishaq Khan Institute of Engineering Sciences & Technology

Quadrants & Plane of Projection

Quadrant System • If the Horizontal and the frontal planes are extended to an infinite distance, they will form a quadrant system. • Each of the quadrant has specific name and properties

2nd Q

1st Q

3rd Q

4th Q

Note Q = Quadrant

Projection of Points  The position of a point in the quadrant system can be better judged by the provided statement. 1. In front of Vertical plane (VP) 2. Behind the Vertical plane (VP) 3. Above the Horizontal plane (HP) 4. Below the Horizontal plane (HP)

 The distance from the vertical plane is visible in the top view.  The distance from the Horizontal plane is visible in the front view.

Projection of Points With Reference to H.P.

With Reference to V.P.

Above

In Front

Below

Behind

Within

Within

Nine possible positions with respect to the two reference planes. Above the H.P. & In Front of the V.P.

1st Q

Above the H.P. & Behind the V.P.

2nd Q

Below the H.P. & Behind the V.P.

3rd Q

Below the H.P. & In Front of the V.P.

4th Q

Above the H.P. & Within the V.P.

-----

Below the H.P. & Within the V.P.

-----

Within the H.P. & In Front of the V.P.

-----

Within the H.P. & Behind the V.P.

-----

Within the H.P. & Within the V.P.

On the Reference Line

Point Infront VP and Above HP Front View Elevation (F.V.) Point X

Plan (T.V.) Final representation on paper.

Top View

Y

Point Behind VP and Above HP Front View Top View

Elevation (F.V.) Plan (T.V.) X

Point

Final representation on paper.

Y

Point Behind VP and Below HP

Plan (T.V.) X Top View Elevation (F.V.) Final representation on paper.

Point Front View

Y

Point Infront VP and Below HP

Top View X Elevation (F.V.) Plan (T.V.) Final representation on paper.

Front View Point

Y

Point Lying on a Plane

Top View

Elevation (F.V.) X Plan (T.V.) Front View Final representation on paper.

Point

Y

Point Lying on Origin Front View Top View

Elevation (F.V.) X Plan (T.V.)

Final representation on paper.

Point

Y

Projection of Lines Positions of a straight lines w.r.t Horizontal and Vertical Planes

1. Parallel to both planes 2. Perpendicular to one plane (must be parallel to the other plane) –

Perpendicular to the H.P. (must be parallel to the V.P.)

–

Perpendicular to the V.P. (must be parallel to the H.P.)

3. Inclined to one plane and parallel to the other plane

–

Inclined to the H.P. and parallel to the V.P.

–

Inclined to the V.P. and parallel to the H.P.

4. Inclined to both planes

Line Parallel to both Planes 1st Quadrant

Front View

Elevation (F.V.) a´

b´

b´

X

Y

B

a´

A

b

Plan (T.V)

a

b

a

Top View

In this case both ab and a΄b΄ will be equal in length and both will represent true length of line AB. Both ab and a΄b΄ will be parallel to XY line.

Line Perpendicular to Horizontal Plane 1st Quadrant Elevation (F.V.)

Front View

a´

b´

X

B a´

A

Plan (T.V)

b´

Y

ab

ab

Top View

In this case elevation a´b´ will show the true length of the line, whereas the plan of the line will be a point represented by ab.

Line Perpendicular to Vertical Plane 1st Quadrant Elevation (F.V.)

Front View

a´ b´

a´ b´

X A

Y a

B

Plan (T.V)

Top View

b

In this case plan ab will show the true length of the line, whereas the elevation of the line will be a point represented by a´b´.

Line Inclined to Horizontal Plane

b´1

1st Quadrant Elevation (F.V.)

Front View b´



a´

b´

B

X

Y

a´ a

A

b

b1

b

Plan (T.V)  = angle w.r.t. to HP

a

Top View

In this case the elevation will show its true length and true inclination with HP. The length of the plan will be shorter than the length of the line itself.

Line Inclined to Vertical Plane 1st Quadrant Elevation (F.V.)

Front View

a´

 = angle w.r.t. to VP b´1 b´

b´

X

Y

a´ B

a

b



Plan (T.V)

A b

b1

a

Top View

In this case the plan will show the true length and inclination with the VP. The elevation will be shorter in length than the true length of the line itself.

Line Inclined to Both Planes b´2

1st Quadrant

b´

Elevation (F.V.)

Front View b´

a´

B



b´1

X

Y

a´ a

b



A

Plan (T.V.) b a b2 b1

Let  be the angle w.r.t. HP and  be the angle w.r.t. VP.

Top View

In this case neither plan nor elevation will show the true length and true inclinations.

Example: Line Inclined to Both Planes Example:

A line AB 80 mm long has its end A 30 mm above the H.P. and 20 mm in front of the V.P. The line is inclined at 30º to the H.P. and at 45º to the V.P. Draw its projections. Given: AB = 80 mm = T.L. End A is 30 mm above H.P. and 20 mm in front of V.P. True Inclination with H.P. = θ = 30º True Inclination with V.P. = Φ = 45º

Solution: Line Inclined to Both Planes 1. Firstly assuming AB parallel to VP and inclined at an angle of 30º to HP. Draw its elevation a´b´ and plan ab.

Elevation (F.V.)

2. Similarly now assume AB to be parallel to HP and incline to VP at an angle of 45º. Draw ab1 (plan) and a´b1´ (elevation). 3. Now with a´ as center and radius equal to a´b1´ draw an arc intersecting line B(F.V). Join a´ and b2´.

Plan (T.V.)

4. Now with a as center and radius equal to ab draw an arc intersecting line B(T.V). ANS: Lines ab2 and a´b2´ are the required projections of Join a and b2. line AB.

Finding the True Length & Angles of Line When a line is inclined to both the reference, its projection will neither show true length nor true inclination. The following are the methods of determining true length and true inclination of the line when line is inclined to both the planes.

1. Rotation Method 2. Auxiliary Method

Rotation Method Example: A line AB has its end A 30 mm above the H.P. and 20 mm in front of the V.P. The front view of the line 65 mm long and is inclined at 60º to the xy line whereas its top view is inclined at 45º to the xy line. Draw the projections of the line AB and find its true length. Also find its true inclinations with the H.P. and the V.P. Given: Line AB End A is 30 mm above H.P. and 20 mm in front of V.P. Length of Front View = 65 mm Angle of Front View = α = 60º Angle of Top View = β = 45º

Solution: Finding the True Length & Angles of Line 1. Draw the 65mm front view a´b´ of the line inclined at an angle of 60º w.r.t. XY line. Project a vertical line from the end b´.

Elevation (F.V.)

2. Now draw a line ab at an angle of 45º w.r.t. to XY line from the point a, until it intersect with the vertical line. 3. Now with a´ as center and radius equal to a´b´ draw an arc intersecting line A(F.V.). Join a´b2´. Project point b2´ vertically until it intersects B(T.V). Join ab2. 4. Perform the procedure in the T.V.

Plan (T.V.)

same ANS: True length of line is a´b1´ or ab2.  is the true angle w.r.t. HP and  is the true angle w.r.t. VP.

Assignment # 2 A line AB has its end A (20+x) mm below the H.P. and (30+x) mm behind the V.P. The front view of the line (40+x) mm long and is inclined at (45+x)º to the xy line whereas its top view is inclined at (65+x)º to the xy line. Draw the projections of the line AB and find its true length. Also find its true inclinations with the H.P. and the V.P. Where x = last digit of your registration number.

Instructions Use the rotation method Submit on a single A4 paper with margins and title box. Submission Deadline: next Class Submit in class no submission to TA or me at office accepted.

Thank you… End of Lecture 4

ME-102 Engineering Graphics Lecture #: 5

Dimensioning

Faculty of Mechanical Engineering Ghulam Ishaq Khan Institute of Engineering Sciences & Technology

DEFINITION Dimensioning is the process of specifying part’ s information by use of figures, symbols and notes. This information are such as: 1. Sizes and locations of features 2. Material’s type 3. Number required 4. Kind of surface finish 5. Manufacturing process

6. Size and geometric tolerances

DIMENSIONING SYSTEM 1. Metric system : ISO and JIS standards Examples 32, 32.5, 32.55, 0.5 (not .5) etc.

2. Decimal-inch system Examples 0.25 (not .25), 5.375 etc.

3. Fractional-inch system 3 1 , Examples 5 4 8

etc.

This course

DIMENSIONING COMPONENTS Extension lines Dimension lines (with arrowheads)

Drawn with 4H pencil

Leader lines Dimension figures

Notes : - local note - general note

Lettered with 2H pencil.

EXTENSION LINES indicate the location on the object’s features that are dimensioned.

DIMENSION LINES indicate the direction and extent of a dimension, and inscribe dimension figures. 27

13

10

43

Arrow Head for Dimension Lines

LEADER LINES indicate details of the feature with a local note.

27

10 Drill, 2 Holes R16

13

10

43

EXTENSION LINES Leave a visible gap (≈ 1 mm) from a view and start drawing an extension line. Extend the extension lines beyond the (last) dimension line 1-2 mm.

COMMON MISTAKE Visible gap

EXTENSION LINES Do not break the lines as they cross object lines.

Continuous

DIMENSION LINES Dimension lines should not be spaced too close to each other and to the view.

34

11

35

16

Leave a space at least 2 times of a letter height.

Leave a space at least 1 time of a letter height.

DIMENSION FIGURES The height of figures is suggested to be 2.5~3 mm. Place the numbers at about 1 mm above dimension

line and between extension lines.

11 34

11

34

COMMON MISTAKE

DIMENSION FIGURES When there is not enough space for figure or arrows, put it outside either of the extension lines.

Not enough space for figures 16.25

16.25

Not enough space for arrows 1

1

1

or

DIMENSION FIGURES : UNITS The JIS and ISO standards adopt the unit of Length dimension in millimeters without

specifying a unit symbol “mm”. Angular dimension in degree with a symbol “o” place behind the figures (and if necessary minutes and seconds may be used together).

LOCAL NOTES Place the notes near to the feature which they apply, and should be placed outside the view. Always read horizontally.

10 Drill ≈ 10mm

10 Drill

Too far

10 Drill

COMMON MISTAKE

THE BASIC CONCEPT Dimensioning is accomplished by adding size and location information necessary to manufacture

the object. This information have to be Clear Complete

Facilitate the - manufacturing method - measurement method

EXAMPLE

L

L

S

L

Designed part

L

S

To manufacture this part we need to know…

2. Diameter and depth of the hole. 3. Location of the holes.

S

1. Width, depth and thickness of the part.

S

“S” denotes size dimension. “L” denotes location dimension.

ANGLE To dimension an angle use circular dimension line having the center at the vertex of the angle. COMMON MISTAKE

FILLETS AND ROUNDS Give the radius of a typical fillet only by using a local note. If all fillets and rounds are uniform in size, dimension may be omitted, but it is necessary to add the note “ All fillets and round are Rxx. ” R6.5

R12

NOTE: All fillets and round are R6.5

Drawing sheet

NOTE: All fillets and round are R6.5 unless otherwise specified.

CYLINDER Diameter should be given in a longitudinal view

 70

 100

with the symbol “ ” placed before the figures.

HOLES Size dimensions are diameter and depth. Location dimension must be located from its center lines and should be given in circular view. Measurement method

HOLES : SMALL SIZE Use leader line and local note to specify diameter and hole’s depth in the circular view. 1) Through thickness hole

 xx Thru.

 xx or

or

xx Drill.

or

xx Drill, Thru.

HOLES : LARGE SIZE Use extension and dimension lines

 xx

Use diametral dimension line

Use leader line and note

CHAMFER Use leader line and note to indicate linear distance and angle of the chamfer.

S q S

For a 45o chamfer or CS

S S

ROUNDED-END SHAPES Dimensioned according to the manufacturing

method used.  12

R12

5

21

Center to Center Distance

RECOMMENDED PRACTICE 1. Extension lines, leader lines should not cross dimension lines. POOR

GOOD

RECOMMENDED PRACTICE 2. Extension lines should be drawn from the nearest points to be dimensioned. POOR

GOOD

RECOMMENDED PRACTICE 3. Extension lines of internal feature can cross visible lines without leaving a gap at the intersection point. WRONG

CORRECT

RECOMMENDED PRACTICE 4. Do not use object line, center line, and dimension line as an extension lines. POOR

GOOD

RECOMMENDED PRACTICE 5. Avoid dimensioning hidden lines. POOR

GOOD

RECOMMENDED PRACTICE 6. Place dimensions outside the view, unless placing them inside improve the clarity. POOR

GOOD

RECOMMENDED PRACTICE 6. Place dimensions outside the view, unless placing them inside improve the clarity. JUST OK !!!

BETTER

RECOMMENDED PRACTICE 7. Apply the dimension to the view that clearly show the shape or features of an object. POOR

GOOD

RECOMMENDED PRACTICE 8. Dimension lines should be lined up and grouped together as much as possible. POOR

GOOD

RECOMMENDED PRACTICE 9. Do not repeat a dimension. POOR

GOOD

QUIZ No. 1… th 28

Feb 2017 (Tuesday)

AS COMMUNICATED BY DIRECTOR (A/E) OFFICE

Thank you…. End of Lecture 5

ME-102 Engineering Graphics Lecture #: 6

Sectioning

Faculty of Mechanical Engineering Ghulam Ishaq Khan Institute of Engineering Sciences & Technology

SECTIONING

PURPOSES OF SECTION VIEWS Clarify the views by ❖ reducing or eliminating the hidden lines. ❖ revealing the cross sectional’s shape.

Facilitate the dimensioning.

Let See the example

EXAMPLE : Advantage of using a section view.

CUTTING PLANE Cutting plane is a plane that imaginarily cuts the object to reveal the internal features. Cutting plane

Cutting plane line

Section lines

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

Indicate the path of cutting plane.

CUTTING PLANE LINESTYLES Thick line ANSI standard Thick line

Viewing direction Viewing direction

TS & ISO standard

Thin line

Viewing direction

SECTION LINING Section lines or cross-hatch lines are used to indicate the surfaces that are cut by the cutting plane.

Section lines Drawn with thin lines.

SECTION LINES SYMBOLS The section lines are different for each of material’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 PRACTICE The spaces between lines may vary from 1.5 mm for small sections to 3 mm for large sections. COMMON MISTAKE

SECTION LINING PRACTICE It should not be drawn parallel or perpendicular

to contour of the view. COMMON MISTAKE

TREATMENT OF HIDDEN LINES Hidden lines are normally omitted from section views.

TYPES 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)

FULL SECTION VIEW The view is made by passing the straight cutting

plane completely through the part.

OFFSET SECTION VIEW The view is made by passing the bended cutting

plane completely through the part.

Do not show the edge views of the cutting plane.

HALF SECTION VIEW The view is made by passing the cutting plane halfway through an object and remove a quarter of it.

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.

BROKEN-OUT SECTION VIEW 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 A break line is used to separate the sectioned portion from the unsectioned portion of the view.

Break line is a thin continuous line (0.25) and is drawn freehand. There is no cutting plane line.

EXAMPLE : Comparison among several section techniques

REVOLVED SECTION VIEW 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 Basic concept

REVOLVED SECTION VIEW Basic concept

REVOLVED SECTION VIEW Placement of revolved section 1. Superimposed to orthographic view. 2. Break from orthographic view.

Break

Superimposed

REVOLVED SECTION VIEW

REMOVED SECTION VIEW Removed section is revolved section.

Section view is shown outside the view. Used where space does not enough for revolved section Can be located elsewhere on a drawing with properly labeled It may be appropriate to use removed sections, for beams or arms etc,

REMOVED SECTION VIEW Note the absence of viewing arrows.

REMOVED SECTION VIEW Revolved section

Removed section

REMOVED SECTION VIEW Poor

Too messy !!

Preferred

Conventional Breaks • Conventional breaks are used to shorten elongated part. • This allows to draw a part at larger scale.

End of Lecture 6 Thank you….

ME-102 Engineering Graphics Lecture #: 8

Orthographic Writing & Reading,

Tangency & Intersection Faculty of Mechanical Engineering Ghulam Ishaq Khan Institute of Engineering Sciences & Technology

DEFINITION Orthographic writing is the process of presenting the object’s Geometric features with the help of the orthographic views. Reading a drawing is the process of recognizing the shape of an object by interpreting the orthographic views.

Orthographic Writing Orthographic Reading

STEP 1 : Orient the Object The object should be placed in its natural position. The object should presents its features in actual

size and shape in orthographic views. GOOD

NO !

STEP 2 : Select a Front View The object’s longest dimension should be presented as a

width. First choice

Second choice

Waste more space

Inappropriate

GOOD

STEP 2 : Select a Front View The adjacent views that are projected from the selected front view should appear in its natural position.

Inappropriate

STEP 2 : Select a Front View Choose the view that have the fewest number of hidden lines.

GOOD

Inappropriate

STEP 3 : Select an Adjacent View Choose the minimum number of views that can represent the major features of the object. Necessary

Hole’s location can be specified on the same view.

Easy to understand Difficult to interprete.

Necessary

STEP 3 : Select an Adjacent View Choose the view that have the fewest number of hidden lines. GOOD

Inappropriate GOOD Inappropriate

STEP 3 : Select an Adjacent View Choose the views that are suitable to a drawing space.

POOR

Not enough space for dimensioning.

STEP 3 : Select an Adjacent View Choose the views that are suitable to a drawing space.

GOOD

ONE-VIEW DRAWING Flat part having a uniform thickness.

1 Thick

Unnecessary These 2 views provide only information about the part thickness !

ONE-VIEW DRAWING Cylindrical-shaped part.

Unnecessary

Repeat ! Infer from CL

Unnecessary

TWO-VIEW DRAWING There exists an identical view. Repeat ! Unnecessary

TWO-VIEW DRAWING The 3rd view has no significant contours of the object.

Unnecessary

TWO-VIEW DRAWING

Unnecessary

Orthographic Reading Objects are Analyzed by Close Consideration of

solid geometric primitives and their surfaces. Some of familiar solid objects Rectangular prism Cylinder

Negative cylinder (Hole)

BASIC IDEA Objects are decomposed into solid geometric

primitives. Some of familiar solid objects Cone

Pyramid Sphere

READING STEPS 1. Orient yourself with the views given. (Choose the viewing direction.) 2. Read the individual surfaces that appeared in each view and related to each other.

3. Create a proper solid geometric primitive from each reading. 4. Assembly all of solid geometric primitive according to orthographic views.

EXAMPLE A Given

Composition Rectangular prism Hole

Front View

EXAMPLE B Given

Composition Rectangular prism

Cylinder

Front View

EXAMPLE C Given

Composition Cylinder with a blind hole. L-shaped with round end Hole

EXAMPLE D Given

Composition

Wedge

EXAMPLE D Given

Composition

Wedge L-shaped block

GUIDANCE 1 Adjacent areas that are not in the same plane must be

separated by lines. Different plane Same plane Line exists Edge view Edge view

EXAMPLE Top view

B

All surfaces A, B and

A

C are not in the same plane.

C Some of possible objects’ shape. A

A

A C

B

B C

B

C

TANGENT & INTERSECTION No line is formed when curved surface tangent to a plane surface. Line is formed when curved surface intersects a plane surface. No line

tangent

intersect No line

tangent

intersect

TANGENT & INTERSECTION

limiting element

tangent

tangent tangent intersect

plane

TANGENT & INTERSECTION tangent

intersect

tangent

No line

tangent

No line

No line tangent

tangent

tangent

End of Lecture 8 Thank you….

ME-102 Engineering Graphics Lecture # 10

Engineering Curves

Faculty of Mechanical Engineering Ghulam Ishaq Khan Institute of Engineering Sciences & Technology

ENGINEERING CURVES INVOLUTE

1. Involute of a circle a)String Length = D b)String Length > D c)String Length < D

CYCLOID

1. General Cycloid

4. Epi-Cycloid 5. Hypo-Cycloid

SPIRAL

1. Spiral of One Convolution. 2. Spiral of Two Convolutions.

HELIX

1. On Cylinder 2. On a Cone

Loci A loci (plural of locus) is the path traced out by a point moving in accordance with a definite law. A simple example of a loci: One of the most common loci is that of a point, which moves, so that its distance from another fixed point remains constant: this produces a circle, as shown below. R= radius C

Dividing the Circle

Involute Curve • The involute is the path of a point on a straight line which rolls (without slipping) around a circle. • It can best be visualized by imagining a piece of string wound around a cylinder. If the string is unwound and kept taut, the free end will trace an involute.

Problem: Draw involute of an equilateral triangle of 35 mm sides.

35

3X35 105

Problem: Draw involute of a square of 25 mm sides

25

100

Draw Involute of a circle. String length is equal to the circumference of circle.

INVOLUTE OF A CIRCLE

Solution Steps:

1) Point or end P of string AP is exactly D distance away from A. Means if this string is wound round the circle, it will completely cover given circle. P will meet A after winding. 2) Divide D (AP) distance into 8 number of equal parts. 3) Divide circle also into 8 number of equal parts. 4) Name after A, 1, 2, 3, 4, etc. up to 8 on D line AP as well as on circle (in anticlockwise direction). 5) To radius C-1, C-2, C-3 up to C-8 draw tangents (from 1,2,3,4,etc to circle). 6) Take distance 1 to P in compass and mark it on tangent from point 1 on circle (means one division less than distance AP). 7) Name this point P1 8) Take 2-P distance in compass and mark it on the tangent from point 2. Name it point P2. 9) Similarly take 3 to P, 4 to P, 5 to P up to 7 to P distance in compass and mark on respective tangents and locate P3, P4, P5 up to P8 (i.e. A) points and join them in smooth curve it is an INVOLUTE of a given circle.

P2

P3

P1

4 to p

P4

4

3

5

2 6 7 P5

1 A

8 P8

1

2

3

4

P7 P6

D

5

6

7

P 8

Involute Gear

• Used in the design of spur gears • The contact surfaces b/w gear teeth are design as involutes.

Drawing Gears

Helix Curve Helix is an important locus being the basic form of the screw thread. It can be regarded as a line of uniform gradient on a cylinder.

Helix Curve - Construction 1. Draw the top and front view of the given cylinder. 2. Divide the top view into 12 equal divisions. Then project the divisions upwards as vertical lines to the front view. 3. Divide the lead into 12 equal divisions, using the method for dividing a line. Project the divisions as horizontal lines across the front view. Then number the points as shown. 4. For each point on the circle, follow the vertical line upwards until you reach the horizontal line(s) with the same number, and make a mark.

4. Join these points. The result is a helix curve.

Examples – Springs

Square Section

Round Springs

Practical examples.

Draw a spiral of one convolution. Take distance PO 40 mm.

SPIRAL

IMPORTANT APPROACH FOR CONSTRUCTION! FIND TOTAL ANGULAR AND TOTAL LINEAR DISPLACEMENT AND DIVIDE BOTH IN TO SAME NUMBER OF EQUAL PARTS. 2

3

Solution Steps 1. With PO radius draw a circle and divide it in EIGHT parts. Name those 1,2,3,4, etc. up to 8 2 .Similarly divided line PO also in EIGHT parts and name those 1,2,3,-- as shown. 3. Take O-1 distance from op line and draw an arc up to O1 radius vector. Name the point P1 4. Similarly mark points P2, P3, P4 up to P8 And join those in a smooth curve. It is a SPIRAL of one convolution.

P2

P1

1

P3

P4

4

O

P5

7 6 5 4 3 2 1 P7 P6

7

5

6

P

Cycloid The cycloid is the locus of a point on the circumference of a circle which rolls, without slipping, on a straight line.

Draw locus of a point on the periphery of a circle which rolls on straight line path. Take circle diameter as 50 mm. Draw normal and tangent on the curve at a point 40 mm above the directing line. 6

7

p6

p5

5

p7 p8

4 p4

8 C1

9

C2

p3

C3

C4

C5

C6

2

C10

p9 C11

C12

p11 p12

1 12 P

C9

p10

p1 11

C8

3

p2 10

C7

D

CYCLOID Solution Steps: 1) 2) 3) 4) 5) 6) 7)

From center C draw a horizontal line equal to D distance. Divide D distance into 12 number of equal parts and name them C1, C2, C3__ etc. Divide the circle also into 12 number of equal parts and in anticlockwise direction, after P name 1, 2, 3 up to 12. From all these points on circle draw horizontal lines. (parallel to locus of C) With a fixed distance C-P in compass, C1 as center, mark a point on horizontal line from 1. Name it P. Repeat this procedure from C2, C3, C4 up to C12 as centers. Mark points P2, P3, P4, P5 up to P12 on the horizontal lines drawn from 1,2, 3, 4, 5, 6, 7 respectively. Join all these points by curve. It is Cycloid.

Assignment # 3 Instructions DRAW EPI CYCLOID (Odd Reg Numbers) DRAW HYPO CYCLOID (Even Reg Numbers) Submit on a single A4 paper with margins and title box. Submission Deadline: In

Next Class .

ZERO Marks for Late submission.

DRAW LOCUS OF A POINT ON THE PERIPHERY OF A CIRCLE WHICH ROLLS ON A CURVED PATH. Take diameter of rolling Circle 50 mm And radius of directing circle i.e. curved path,

75 mm. Solution Steps:

1) When smaller circle will roll on larger circle for one revolution it will cover D distance on arc and it will be decided by included arc angle . 2) Calculate  by formula  = (r/R) x 3600. 3) Construct angle  with radius OC and draw an arc by taking O as center OC as radius and form sector of angle . 4) Divide this sector into 12 number of equal angular parts. And from C onward name them C1, C2, C3 up to C12. 5) Divide smaller circle (Generating circle) also in 12 number of equal parts. And next to P in anticlockwise direction name those 1, 2, 3, up to 12. 6) With O as center, O-1 as radius draw an arc in the sector. Take O-2, O-3, O-4, O-5 up to O-12 distances with center O, draw all concentric arcs in sector. Take fixed distance CP in compass, C1 center, cut arc of 1 at P1. Repeat procedure and locate P2, P3, P4, P5 unto P12 (as in cycloid) and join them by smooth curve. This is EPI – CYCLOID.

c9

c8

c10 c11

c7

c12

c6 c5

8

9

10 11

7

12

6

c4 5

c3

4

3

c2

4’

2

3’

2’

c1 5’

1

1’

6’

P 11’

7’ 8’

10’ 9’

θ

12’

C

O

OP=Radius of directing circle=75mm PC=Radius of generating circle=25mm θ=r/R X360º= 25/75 X360º=120º

DRAW LOCUS OF A POINT ON THE PERIPHERY OF A CIRCLE WHICH ROLLS FROM THE INSIDE OF A CURVED PATH. Take diameter of rolling circle 50 mm and radius of

directing circle (curved path) 75 mm.

Solution Steps:

1) Smaller circle is rolling here, inside the larger circle. It has to rotate anticlockwise to move ahead. 2) Same steps should be taken as in case of EPI – CYCLOID. Only change is in numbering direction of 12 number of equal parts on the smaller circle. 3) From next to P in clockwise direction, name 1,2,3,4,5,6,7,8,9,10,11,12 4) Further all steps are that of epi – cycloid. This is called HYPO – CYCLOID.

9

8

10 11

7

12

6 5

4

c7

c8

c9

c10

c11

c6

3

c5

c4 2 2’

3’

c3

4’

c2 1

1’

5’

c1

12’

P 11’

7’

10’

θ

6’

C

O

8’ 9’

OP=Radius of directing circle=75mm PC=Radius of generating circle=25mm θ=r/R X360º= 25/75 X360º=120º

c12

End of Lecture 10 Thank you….

ME-102 Engineering Graphics Lecture # 11

Development of Surfaces

Faculty of Mechanical Engineering Ghulam Ishaq Khan Institute of Engineering Sciences & Technology

Developments A development is the unfolded or unrolled, flat or plane figure of a 3-D object. -Called a pattern, the plane figure may show the true

size of each area of the object. When the pattern is cut, it can be rolled or folded back into the original object.

Development is different…… 1. Development is different drawing than PROJETIONS. 2. It is a shape showing AREA, means it’s a 2-D plain drawing. 3. Hence all dimensions of it must be TRUE dimensions. 4. As it is representing shape of an un-folded sheet, no edges can remain hidden And hence DOTTED LINES are never shown on development.

ENGINEERING APLICATION: There are so many products or objects which are difficult to manufacture by conventional manufacturing processes, because of their shapes and sizes. These products are fabricated in sheet metal industry by using development technique. there is a vast range of such objects. EXAMPLES:Boiler Shells & chimneys, Pressure Vessels, Shovels, Trays, Boxes & Cartons, Feeding Hoppers, Large Pipe sections, Body & Parts of automotive, Ships, Aeroplanes and many more.

APLICATIONS……

Types of Developments • • • •

Parallel-line Development Radial-line Development Triangular Development Approximate Development

▪ Parallel line development uses parallel lines to construct the expanded pattern of each threedimensional shape. The method divides the surface into a series of parallel lines to determine the shape of a pattern. Example: Prism, Cylinder.

▪ Radial line development uses lines radiating from a central point to construct the expanded pattern of each three-dimensional shape. Example: Cone, Pyramid.

▪ Triangular developments are made from polyhedrons, single curved surfaces, and wrapped surfaces. Example: Tetrahedron and other polyhedrons.

▪ In approximate development, the shape obtained is only approximate. After joining, the part is stretched or distorted to obtain the final shape. Example: Sphere.

Development of a Cube

Development of a Prism Draw the development of the following prism

Development of a Prism

Development of lateral surfaces of different solids. (Lateral surface is the surface excluding top & base) Cylinder:

A Rectangle

Cone: (Sector of circle)

Pyramids: (No.of triangles)

H

D

D



H= Height D= base diameter

Prisms:

R=Base circle radius. L=Slant height. R 3600 L

No. of Rectangles

= H

S

S

H= Height S = Edge of base

Tetrahedron: Four Equilateral Triangles

All sides equal in length

L= Slant edge. S = Edge of base

Development of a Cylinder Draw the development of a cylinder of 40 mm diameter and 60 mm high

Development of Truncated Cylinder

Development of Hexagonal Prism Draw the development of a hexagonal prism of base edge 25 mm and axis 60 mm long

Development of a Cone

Development of Cone Radius, R Slant edge length, L Circumference, 2πR

= 20mm = 100mm = 2 x 3.14 x 20 = 125.71 mm Now angle (θ) of arc for cone For development: S=rxθ (here r = L, S= 2 πR) θ = S/r = 125.71/100 = 1.2571 radians θ = 1.2571 x (180/3.14) = 72 degrees

=

R L

3600

Development of Cone

FRUSTUMS DEVELOPMENT OF FRUSTUM OF CONE

DEVELOPMENT OF FRUSTUM OF SQUARE PYRAMID Base side Top side

 =

R 3600 L

R= Base circle radius of cone L= Slant height of cone L1 = Slant height of cut part.

L= Slant edge of pyramid L1 = Slant edge of cut part.

Practice Problem (Pyramid)

(Self Study)

Practice Problem (Truncated Prism)

(Self Study)

Practice Problem (Truncated Cone)

(Self Study)

End of Lecture 11 Thank you….

ME-102 Engineering Graphics Lecture # 12

Joining of Materials (Threaded Fasteners & Welding ) Faculty of Mechanical Engineering Ghulam Ishaq Khan Institute of Engineering Sciences & Technology

Joining of Materials • Joining is the act or process of putting or bringing things together to make them continuous or to form a unit. • As it applies to fabrication, joining is the process of attaching one component, structural element, part to create an assembly, where the assembly of component parts or elements is required to perform functions that are needed or desired and that cannot be achieved by a simple component or element alone. • Engineering applications are mostly consisted of assemblies.

Assemblies • An assembly is a collection of manufactured parts, brought together by joining to perform one or more than one primary function. Three major types of Assemblies • Structural Assemblies • Mechanical Assemblies • Electrical Assemblies

Types of Assemblies •

Structural Assemblies: Primary function is to carry load (static, dynamic or both) Ex: Building, bridges, and dams etc.

•

Mechanical Assemblies: Primary function is to create, enable or permit some desired motion or series of motion through the interaction of properly positioned, aligned and oriented components. Ex: Engines, gear trains, linkages, actuators etc.

•

Electrical Assemblies: Primary function is to create, transmit, process or store electromagnetic signal or stat to perform some desired function. Ex: PCBs, motor, generator, power transformers etc.

Types of Joints • Non-permanent (Temporary) Joints Allows intentional disassembly w/o damaging the assembly.

• Permanent Joint: • Doesn’t allow disassembly once applied

FASTENING TYPE 1. Permanent Welding

Gluing

Riveting

FASTENING TYPE 2. Temporary 2.1 Threaded fastener - bolts - studs - screws 2.2 Non-threaded fastener - keys

- pin

key

THREAD APPLICATION 1. To hold parts together. 2. To move part(s) relative to others.

Part A

Part B Part C

THREAD APPLICATION 1. To hold parts together. 2. To move part(s) relative to others.

Wood working vise

Palm fruit pressing machine

THREAD TERMINOLOGY The largest diameter on

Major diameter

an internal or external thread. The smallest diameter on an internal or external thread.

Major dia.

Internal Thread

Major dia.

Minor dia.

External Thread

Minor dia.

Minor diameter

THREAD TERMINOLOGY Thread Form

Form is the profile shape of the thread.

Example : “knuckle thread form”

EXTERNAL THREAD CUTTING Tools Threading Die

Die stock

Operation

INTERNAL THREAD CUTTING Tools Twist drill

Tap

Tap wrench

Operation

THREAD REPRESENTATION 1. Detailed representation 2. Schematic representation 3. Simplified representation

DETAILED REPRESENTATION Use slanting lines to represent crest and root. Roots and crest are drawn in sharp Vs.

External thread Thread runout

Pitch

60o

Internal thread

SCHEMATIC REPRESENTATION Use alternate long and short lines for representing crests and roots of the thread, respectively.

External thread

Pitch

Internal thread

Root (thick line) Crest (thin line)

SIMPLIFIED REPRESENTATION Use thick continuous lines for representing crest and thin continuous lines for representing root of the thread, respectively.

External thread

Internal thread

Thread runout

Pitch/2

Root Crest

SIMPLIFIED REPRESENTATION Use thick continuous lines for representing crest and thin continuous lines for representing root of the thread, respectively.

External thread

Internal thread

Sectional view

ISO (METRIC) THREAD Internal thread

P/8

60o

P/4

External thread Pitch, P

Center of thread assembly Thread assemble occurs if and only if both (internal & external)

thread have an equal nominal size (or diameter) and pitch.

METRIC COARSE THREAD Nominal size M6 M8 M10 M12

Major diameter

Pitch

Minor diameter

Tap drill size

6.00

1.00

4.92

5.00

8.00 10.00 12.00

1.25 1.50 1.75

6.65 8.38 10.11

6.75 8.50 10.00

Metric thread

Minor diameter ≈ Tap drill size

In thread drawing, the following relationship is used. Minor diameter = Major diameter – Pitch

METRIC FINE THREAD Nominal size

Major diameter

M8

8.00

M10

10.00

Pitch

Minor diameter

Tap drill size

0.75

7.188

7.25

1.00 0.75 1.00

6.917 9.188 8.917

7.00 9.25 9.00

1.25

8.647

8.75

Minor diameter ≈ Tap drill size In thread drawing, the following relationship is used. Minor diameter = Major diameter – Pitch

DIMENSIONING EXTERNAL THREAD Use local note to specify :- thread form, nominal size, pitch (if it is a fine thread) Use typical method to specify :- thread length. M 10 ×1.5 Coarse thread ×1.0 Fine thread

xx

Thread length

DIMENSIONING THREADED HOLE Use local note to specify 1. Tap drill size 2. Drill depth 3. Thread form

4. Nominal size 5. Pitch 6. Thread depth

8.50 Drill, 20 Deep, M10 Tapped, 15 Deep

Unified Threads (inch)

Unified Threads (inch) • Identify the different components of the following Unified National thread note. • 1/4 – 20 UNC – 2A – RH

1/4 20 UNC 2 A RH

.25 inch Major DIA 20 threads per inch (P = 1/20 = .05) Thread form & series – UN Coarse Thread Class – Normal Production External Threads Right Handed Threads

Welding • Joining process in which two (or more) parts are joined at their contacting surfaces by application of heat and/or pressure • Many welding processes are accomplished by heat alone, with no pressure applied • Others by a combination of heat and pressure • In some welding processes a filler material is added to facilitate joining Figure Basic configuration of an welding process

The Weld Joint The junction of the edges or surfaces of parts that have been joined by welding • Two categories about weld joints: – Types of joints – Types of welds used to join the pieces that form the joints

Figure: weld joint

Five Types of Joints 1

1. Butt joint 2. Corner joint

2

3. Lap joint

3

4. Tee joint 5. Edge joint

4 5

Types of Welds • Each of the preceding joints can be made by welding

• Other joining processes can also be used for some of the joint types • There is a difference between joint type and the way it is welded - the weld type • Common weld types

– Fillet Weld – Groove Welds

– Spot Welds

Fillet Welds • Used to fill in the edges of plates created by corner, lap, and tee joints • Filler metal used to provide cross section in approximate shape of a right triangle

Figure Various forms of fillet welds: (a) inside single fillet corner joint; (b) outside single fillet corner joint; (c) double fillet lap joint; and (d) double fillet tee joint. Dashed lines show the original part edges

Groove Welds

• Usually requires part edges to be shaped into a groove to facilitate weld penetration • Grooved shapes include square, bevel, V, U, and J, in single or double sides

• Most closely associated with butt joints

(a) square groove weld, one side; (b) single bevel groove weld; (c) single V-groove weld; (d) single U-groove weld; (e) single J-groove weld; (f) double V-groove weld for thicker sections. Dashed lines show original part edges.

Spot Welds Fused section between surfaces of two plates

• Used for lap joints

Spot Weld

Welding Symbols in Engineering Drawing

Pitch and length of the Weld( Explained in The Picture)

QUIZ No. 2 Next Week, Date and Time will be communicated through COE office

Lecture 10, 11, 12 & Lab Sessions

Thank you…. End of Lecture 12

ME-102 Engineering Graphics Lecture # 13

Geometric Tolerances

Faculty of Mechanical Engineering Ghulam Ishaq Khan Institute of Engineering Sciences & Technology

Geometric Tolerance  No component can practically be manufactured to exact dimensions (sizes).  Tolerances are used to control the variation that exists on all manufactured parts.  It is the amount, each part is allowed to vary depending upon the function of the part and assembly.

 Toleranced dimensions control the amount of variation on each part of an assembly.  When different parts are assembled, they must fit together and function correctly.

Tolerancing / Interchangeability ➢ Tolerancing is dimensioning for interchangeability.

➢ What is interchangeability? An interchangeable part is simply a mass produced part (a replacement part).

Tolerancing / Interchangeability ➢ How is a feature on an interchangeable part dimensioned? SIZE DIMENSION

The feature is not dimensioned using a single value, but a range of values. WHAT DOES THIS MEAN? 2.007 2.003

Tolerancing / Interchangeability ➢ A tolerance is the amount of size variation permitted. → You can choose a tolerance that specifies a large or small variation. 1.005 Size limits = 0.994 Tolerance = 1.005 - .994 = .011

Tolerancing / Interchangeability ➢ Why do we want a part’s size to be controlled by two limits? It is necessary because it is impossible to manufacture parts without some variation. The stated limits are a form of quality control.

Tolerancing / Interchangeability ➢ Choosing a tolerance for your design. → Specify a tolerance with whatever degree of accuracy that is required for the design to work properly. → Choose a tolerance that is not unnecessarily accurate or excessively inaccurate.

Tolerancing Standards ➢ The two most common standards agencies are; → American National Standards Institute (ANSI) / (ASME)

→ International Standards Organization (ISO).

Important Terms ➢ Basic Size (Nominal Size): The theoretical size used as a starting point for the application of tolerance. Or nominal dimension from which tolerances are derived. ➢ Actual Size: The measured size of the finished part after machining. ➢ Limits: The maximum and minimum sizes shown by the tolerance dimension. ➢ Allowance: The minimum clearance or maximum interference between parts, or the tightest fit b/w two mating parts.

Important Terms Maximum material condition (MMC): The condition of the part when it contains the greatest amount of material. The MMC of an external feature (such as shaft), is the upper limit. The MMC of an internal feature (such as a hole), is the lower limit. Least material condition (LMC): The condition of a part when it contains the least amount of material possible. The LMC of an external feature is the lower limit. The LMC of an internal feature, is the upper limit.

Tolerance Representation Types ➢ The tolerancing methods to present tolerances are:

→Limit dimensions →Plus or minus tolerances →Page or block tolerances

Tolerancing Methods a) Limit dimensioning

b) Plus minus Tolerance •

Bilateral Tolerance

•

Unilateral Tolerance

Bilateral Tolerance A bilateral tolerance varies in both direction from the basic size. If the variation is equal in both direction, then the variation is preceded by ± symbol. The ± approach is used when the two variations are equal.

Unilateral Tolerance When the tolerance value is specified in only one direction from the basic size it is known as unilateral tolerance.

Other Approaches Tolerance specified in a tabulated manner.

Tolerance can be specified in a general way to cover for a wide range of dimensions

Types of Fits

Clearance fits - allowance always positive

The degree of tightness between mating parts is called fit.

Clearance Fit (Sliding Fit): In which the shaft is always smaller than the hole into which it fits. A clearance fit always has a gap between the two mating parts.

Interference Fit: In which the shaft is always bigger than the hole into which it fits. Interference fits always overlap and are used mainly for press fits where the two parts are pushed together, and require no other fasteners.

Interference fits - allowance always negative,

Types of Fits…. Transition Fit: • In which the shaft may be either bigger or smaller than the hole into which it fits – it will therefore be possible to get interference or clearance fits in one group of assemblies. • A transition fit exist when the maximum clearance is positive and the minimum clearance is negative

• Transition fits are used only for locating a shaft relative to a hole, where accuracy is important but either a clearance or an interference is permitted. Transition fit—allowance may be positive or negative

Examples • From everyday life, some examples of clearance, interference and transition fits.

Fit Clearance

Example Lock and Key Door and Door frame Coin and Coin slot

Interference

Pin in a bicycle chain Hinge pin Wooden peg and hammer toy

Transition

Piston and cylinder Bearing Assembly

Determining Fits The loosest fit is the difference between the smallest feature A and the largest feature B. The tightest fit is the difference b/w the largest feature A and the smallest feature B.

Systems for Fits and Limits The two bases for a system of limits and fits: (a) The hole basis (b) The shaft basis Hole Basis:

Shaft Basis:

• Hole diameter constant. • Shaft diameter varies. • Economical as only a single drill will be used

• Hole diameter varies. • Shaft diameter constant. • Tends to be costly, as more then one drill is required.

Basic Hole / Basic Shaft Systems • Basic hole system: The basic hole system is used when you want the basic size to be attached to the hole dimension. – For example, if you want to tolerance a shaft based on a hole produced by a standard drill, reamer, broach, or another standard tool.

• Basic shaft system: The basic shaft system is used when you want the basic size to be attached to the shaft dimension. – For example, if you want to tolerance a hole based on the size of a purchased a standard drill rod.

Metric Tolerances • Upper deviation:

The upper deviation is the difference between the basic size and the permitted maximum size of the part.

▪ UD = |Basic size – Dmax| • Lower deviation: The lower deviation is the difference between the basic size and the minimum permitted size of the part.

▪ LD = |Basic size – Dmin|

Tolerance Designation • Fits are specified by using the: – fundamental deviation (letter) – IT# (International Tolerance Grade #). • When specifying the fit: – The hole = upper case letter – The shaft = lower case letter

Available Metric Fits Hole Basis H11/c11

Shaft Basis C11/h11

Fit Loose running

H9/d9 H8/f7

D9/h9 F8/h7

Free running Close running

H7/g6 H7/h6 H7/k6 or H7/n6 H7/p6 H7/s6

G7/h6 H7/h6 K7/h6 or N7/h6 P7/h6 S7/h6

Sliding Locational clearance Locational transition

H7/u6

U7/h6

Force

Locational interference Medium drive

QUIZ No. 2 Next Week, Date and Time will be communicated through COE office

Lecture 10, 11, 12 & Lab Sessions

Thank you….

Geometric Tolerance  Tolerances are used to control the variation that exists on all manufactured parts.  Toleranced dimensions control the amount of variation on each part of an assembly.

Feature of Control Frame

Feature of Control Frame

Tolerance Designation Fits are specified by using the: fundamental deviation (letter)

IT# (International Tolerance Grade #).

When specifying the fit: The hole = upper case letter The shaft = lower case letter

Available Metric Fits Hole Basis H11/c11

Shaft Basis C11/h11

Fit Loose running

H9/d9 H8/f7

D9/h9 F8/h7

Free running Close running

H7/g6 H7/h6 H7/k6 or H7/n6 H7/p6 H7/s6

G7/h6 H7/h6 K7/h6 or N7/h6 P7/h6 S7/h6

Sliding Locational clearance Locational transition

H7/u6

U7/h6

Force

Locational interference Medium drive

Geometric Tolerance  Tolerances are used to control the variation that exists on all manufactured parts.

 Toleranced dimensions control the amount of variation on each part of an assembly.

Feature of Control Frame

Feature of Control Frame

1.Part Drawing

1. Orthographic views 2. Dimensions & Tolerances 3. Surface finishing Title block General note Gen. tolerance Projection Revision table

End of Lecture 14 Thank you….

3. DETAILED ASSEMBLY (working-drawing assembly)

ME-102 Engineering Graphics Lecture # 15

Assembly Drawings

Faculty of Mechanical Engineering Ghulam Ishaq Khan Institute of Engineering Sciences & Technology

3. DETAILED ASSEMBLY (working-drawing assembly)

End of Lecture 15 Thank you….

Welding Symbols in Engineering Drawing

Pitch and length of the Weld( Explained in The Picture)