Mechanical Engineering By Mohammed Imran 114 GPT Karwar

Department of Collegiate and Technical Education

Conventional representation (1)

Machine drawing( III Semester)

Mechanical Engineering

By Mohammed Imran

114 GPT Karwar

Mechanical engineering– 15ME34D

Unit 1 Conventional representation of some

standard material

Machine drawing 15ME34D

Convention for long and short Break

in pipe, rod & shaft


Various section :half and removed


Standard convention for some

common feature 1. Knurling


Chain wheel

Spur gear and

Helical gear


COUNTER BORE

COUNTER SUNK Machine drawing 15ME34D

Unit 2 Threaded fasteners


Conventional representation of external and internal

thread


Top and front view of hexagonal headed bolt with

nut across flat and corner


Square headed bolt with view across corner


Square headed bolt with view across flat

• Width across flat =1.5d+3mm

• Thickness of bolt head =tb=0.8d

• Thickness of nut=tn=0.9d

• Angle of chamfer=30


Eye bolt • The head of the bolt is in the form of circular form of

rectangular cross section it is generally used in inspection

covers lids etc.


Locking devices


2. For square sunk key w=t=d/4


Unit 3 Riveted joints

• Riveted joints are Permanente fasteners and rivet is one of the

commonly used method of producing rigid and Permanente

joints

Types of riveted joints

1.Lap joints

2.Butt joint


Empirical portion of riveted joints

• 1.Diametere of rivet d=6√t

• 2. Longitudinal pitch p=3d

• 3. Margin m=d

• 4. Distance of center of rivet to the edge of plate =1.5d

• 5. Transverse pitch Pt=0.6p (Zig zag)

Pt=0.8p (Chain)

• 6. Thickness of single cover plate t1=1.125t

• 7. Thickness of double cover plate t2=0.7 or 0.8t

• 8 Diametere of snap head =1.6d

• 9.Diagnol pitch Pd=(2p+d)/3 Machine drawing 15ME34D

Sectional front & top view of single riveted lap joint


Sectional front and top view of Double riveted lap joint chain and zigzag


Sectional front and top view of single riveted butt

joint with single and double cover plate


Double riveted but joint with chain riveting with

double cover plate

Double riveted but joint with zigzag riveting

with double cover plate


Unit 4 Limits fits and tolerances


TERMINOLOGY • Basic size: It is the size of a part to which all limits of variation are

determined.

• Actual size: It is the actual measured dimension of a part.

• Limits :There are two extreme possible sizes of a component.

• largest permissible size for a component is called upper limit and

smallest size is called lower limit

• Deviation :It is the algebraic difference between any given size and

Basic size

• Actual deviation: It is the algebraic difference between the actual

Measured size & basic size.

• Lower deviation: it is the algebraic difference between the minimum

limit of size &the basic size

• Upper deviation: It is the algebraic difference between the maximum

limit and the basic size

• Zero line: It is the straight line corresponding to the basic size. The

deviations are measured from this line. Machine drawing 15ME34D

TOLARANCE

• Tolerance :total permissible variation from specified basic size of the part, the difference between the maximum and minimum limits of size. It is always positive.

• Types of tolerances

• 1.Unilateral tolerances: when tolerance is given in one side of the nominal size either above or below known as unilateral tolerance eg 25 +0.005 30 -0.008

• 2.Bilateral tolerances when the tolerance is given on both side of the nominal size it is known as bilateral tolerances

eg 25 +0.005 30 +0.005

-0.008 -0.008


Fits and its types

• The relationship between the two mating parts that are to be

assembled, that is, the hole and the shaft, with respect to the

difference in their dimensions before assembly is called a fit.

• An ideal fit is required for proper functioning of the mating

parts. Three basic types of fits can be identified, depending on

the actual limits of the hole or shaft:

• 1. Clearance fit

• 2. Interference fit

• 3. Transition fit


• Clearance fit: The largest permissible diameter of the shaft is

smaller than the diameter of the smallest hole.


• Interference fit: The minimum permissible diameter of the shaft exceeds the maximum allowable diameter of the hole.


Transition fit

• Transition fits are a compromise between clearance and

interference fits. They are used for applications where accurate

location is important but either a small amount of clearance or

interference is permissible

• This option means that the maximum shaft size is bigger than the

minimum size of the hole. At the same time, the minimum shaft

size is also smaller than the maximum size of the hole.


Fundamental tolerance Machine drawing 15ME34D

• Lets chose the diameter of the shaft 60mm, and Tolerance grade

H8f7; Calculation for Fundamental deviation, Tolerances and Limit

of size for Hole and, Shaft.

• Calculation of the Standard tolerance Unit;

• The size range for 60mm Diameter would be 50-80mm from the

ISO 286 table

• D=√ 50 +80 mm=63.25mm

• i=0.45D ^(1/3)+0.01x63.25 i=1.865 ϻm

• For Shaft of f7 "i" value standard unit from the table;

• Tolerance=16i=16x1.865=0.030mm

• For Hole of H8 "i" value standard unit from the table;

• Tolerance=25i=25x0.001865=0.046mm


• Since design based on Hole basis, the fundamental

deviation of hole is zero. Fundamental deviation for

Shaft;

• =-5.5xD^0.41

• =-5.5x63.25^0.41

• =-30.114 microns=0.030mm

• Shaft;

• Higher Limit=Basic size-Fundamental Deviation=60-

0.030=59.97mm

• Lower Limit=Higher Limit-Tolerance=59.97-

0.03=59.94mm

• Hole;

• Lower Limit=Basic Size=60mm

• Higher Limit=Lower

Limit+Tolerance=60+0.046=60.046mm Machine drawing 15ME34D

Unit 5 Production drawing

A production drawing provides information like dimension

with limits, tolerance and special finishing process such as

heat treatment,hoining ,lapping surface finish and material

used etc

Surface finish after marching the machined surface depends

on the material machined, cutting condition such as

sharpness of tool ,coolant used, depth of cut, amount of feed

etc

The quality of surface finish required for the surface is

indicated on the drawing and is known as surface texture.

Symbols for indicating surface Texture

Indication of surface roughness by values The values of surface roughness Ra is expressed in micrometere.

Indication of surface roughness by Symbols

Unit 6 DETAILS TO ASSEMBLY

• A drawing which displays the parts of a machine or a machine unit

assembled in

• their relative working positions is known as assembly drawing.

• The assembly drawing would be such that it should satisfy:

• (i) Manufacturing requirements

• (ii) Operational requirements

• (iii) Maintenance requirements.

Norms to be observed in preparing assembly

drawings • (i) Selection of views: The main or important view which is

usually in section should show all the individual parts and their

relative locations. Additional views are shown only when they add

necessary information.


• (ii) Sectioning: The parts should be sectioned according to

the requirements (i.e. half-section or partial section) to show

important assembly details. Code of the BIS ( SP:46-1988)

for general engineering drawings must be observed

• (iii) Dotted lines: The dotted lines should be omitted from

the assembly drawing when a proper section is taken. If the

view of a part is drawn by the half-section, then in un

section portion of the view, the dotted lines may be drawn to

clarify details of the part. (iv) Dimensions: The overall

dimensions and center-to centre distances showing the

relationship of parts to the machine as a whole, are

sometimes shown.

• (V) Detailed dimensions are given on working assembly

drawings when the detailed drawings are not prepared.


Bill of Materials • Bill of materials: Each part of the machine is identified on

assembly drawing by the leader line and number, which are used in

the detail drawing and in the bill of material. The height of the

number may be approximately 5 mm and encircled by 9 mm

diameter. Leader lines are drawn radially touching the respective

parts.

• The bill of materials also shows the following:

(a) Number of parts (e) Method of projection

(b) Material of parts (f) Shop processes required for one unit

(c) Standard norm for (g) Name of the company

(d) Scale (h) Designed by, drawn by

(i) Any special remark.


Sequences of preparing the assembly drawing

• (i) Study functional requirements of each component and their

inter relationship.

Learn the actual working of a machine.

• (ii) Study carefully the views of each component in the detail

drawing and decide the relative location of each part for the

proper functioning of the machine

.

• (iii) Decide the mating dimensions between two components

which are required to be assembled.

• iv) Prepare free-hand sketch of the main view or an important

view (generally front-elevation). Add additional views, if

necessary. Machine drawing 15ME34D

• (v) Select a suitable scale for the entire assembly drawing.

• (vi) Layout the views of the assembly drawing so that it

become easier to Understand.

• (vii) Prepare the bill of materials.

• (viii) Label each component by the leader-line and number it

.

• (ix) Show overall dimensions.

• (x) Draw the section-lines according to the convention

• (xi) Show required fits and tolerances between the two mating

components.

SOCKET AND SPIGOT JIONT


COTTER AND SPIGOT JOINT ASSEMBLY

3

2 1


KNUKCLE JOINT


KNUCKLE JOINT ASSEMBLY

1

2

3

4

5


DETAILS OF UNIVERSAL COUPLING


ASSEMBLY OF UNIVERSAL COUPLING 1 2

3

7

4

6

5


DETAILS OF PROTECTED TYPE FLANGED

COUPLING


ASSEMBLY OF PROTECTED TYPE FLANGED

COUPLING 1 2

5 3 4

6


DETAILS OF SCREW JACK


SCREW JACK ASSEMBLY


DETAILS OF PLUMMER BLOCK


ASSEMBLY OF PLUMMER BLOCK


Mechanical Engineering By Mohammed Imran 114 GPT Karwar

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