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Chapter 14
Working Drawing
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TOPICS
Introduction
Detail drawing
Assembly drawing
Assembly section
Dimensioning
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In t roduc t ion
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DEFINITION
Work ing d rawing is a set of drawing usedduring the work of making a product.
Working d raw ing
Detaildrawing
A s s e m b l ydrawing
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DEFINITION
Detai l dr awin g is a m ult iv iew representa t ion
of a single part with d imens ions and notes .
Ass em bly d raw ing is a drawing of variousparts of a machine or structure assembled in
their relative working positions.
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Detai l dr awin g conveys the in fo rmat ion and i n s t ruc t i ons for manufacturing the part.
4. functional relationship among various
components.
1. completed shape of the product.
2. overall dimensions.
PURPOSE
Ass em bly d rawing conveys
3. relative position of each part.
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Detai l Draw in g
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INFORMATION IN
DETAIL DRAWING
2.1 Shape description
2.2 Size description
2.3 Specifications
1. General information
2. Part s information
Title block
Objects
views
Notes
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GENERAL INFORMATION Name of company
Title of drawing (usually parts name)
Drawing sheet number
Name of drafter, checker
Relevant dates of action
(drawn, checked, approved etc.)
Revision table Unit
Scale
Method of projection
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PART S INFORMATION
Orthographic drawing Pictorial drawing
Dimensions and Tolerances
Specifications
General notes
Type of material used
Surface finish
General tolerances
Part number, name,number required
Shape
Size
Heat treatment
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If not the case ,
- apply enou gh spac ing between parts.
-draw all parts using the sam e sc a le .
-Otherwise, the scale should be clearly note
under each parts drawing .
Draw one part to one sheet of paper .
RECOMMENDED PRACTICE
Standard parts such as bol t , n u t , p in , bear ing
do not require detail drawings.
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Part No., Part name, material, Number required
NotesUnit, fillets & rounds sizes etc.
Completed dimension
orthographic drawing
Title block
PLACING AN INFORMATION(This course)
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EXAMPLE : Interpreting detail drawing
General note
Revision table
Title block
1. Orthographicviews
2. Dimensions& Tolerances
3. Surfacefinishing
ProjectionGen. tolerance
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A ss em b ly Draw ing
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1. Exploded assembly drawings
3. Detail assembly drawings
TYPES OF ASSEMBLY DRAWING
2. General assembly drawings.
The parts are separately display, but they are aligned
according to their assembly positions and sequences.
All parts are drawn in their working position.
All parts are drawn in their working position with a
completed dimensions.
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1. EXPLODED ASSEMBLY
Pictorial representationFinished product
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1. EXPLODED ASSEMBLY
Orthographic representation
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2. GENERAL ASSEMBLY
Pictorial Orthographic
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Only dimensions relate tomachines operation aregiven.
Only dimensions relate to
machines operation are given
in tabulated form (not shown).
2. GENERAL ASSEMBLY
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2. GENERAL ASSEMBLY
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3. DETAILED ASSEMBLY(working-drawing assembly)
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- Assembled parts
- Reference numbers
General notesTitle block
Part list
PLACING AN INFORMATION(This course)
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PART LIST (BOM) (This course)
NO. PART NAME REQD. MATL. & NOTE
1 SUPPORT 2 Cast Iron
2 SHAFT 1 Stainless Steel
3 SET SCREW 1 Stainless Steel,M3 HEX SOCK CUP PT
Locate above or beside the title block.
Fill the table from the bottom.
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EXAMPLE : Another allowable place for BOM
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STEPS TO CREATEASSEMBLY DRAWING
4. Draw a view of m ajor par t s according to a
selected viewing direction.
3. Choos e major pa r ts , i.e. parts that have
several parts assembled on.
1. Analyze geometry and dimensions of all partsin order to understand the assembly steps and
overall shape of device or machine.
2. Select an appropriate view.
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6. Applysec t ion t echn iqu e
where relativepositions between adjacent parts are needed
to clarify.
7. Add bal loons , notes and dimens ions (if any).
5. Add detail view of the remaining parts at their
working positions.
8. Create BOM.
STEPS TO CREATEASSEMBLY DRAWING
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GENERAL PRACTICE
The num ber o f v iews can be one, two, threeor more as needed, but it should be minimum .
A good view ing d i rec t ion is that represents all
(or most) of the parts assembled in their working
position.
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Part A Part B
EXAMPLE : Selection of a necessary view
Given
Student A Student B
Which is an appropriate view for assembly drawing ?
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GENERAL PRACTICE
Hidden l ines usually omit unless they areabsolutely necessary to illustrate some
important feature that the reader might
otherwise miss.
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EXAMPLE : Hidden lines omit o r n o t ?
Part A
Part B
A
B
C
Good Poor
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EXAMPLE : Hidden lines omit o r n o t ?
Part A
Part B
A
B
Good Poor
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EXAMPLE : Hidden lines omit o r n o t ?
Part A
Part B
A
B
Good Poor
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GENERAL PRACTICESec t ion t ech n ique is usually need to clarify
mating of the parts.
Correct
Better
Part A
Part B
OFF
Use different section line styles for adjacent parts.
ONColor
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Do no t draw section lines on sectional view of
standard parts.
- Threaded fastener
- Washer- (longitudinal cut of) Solid shaft, Pin, Key
SECTION LINE PRACTICE
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EXAMPLE 1 : Assembly steps
3 PIN, Steel, 1 REQD.
2 ARM, Steel, 1 REQD.
1 CLEVIS, Steel, 1 REQD.
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EXAMPLE : Section line practice
A
BWhich is an appropriate
full section view of thisassembly ?
Good Poor
OFF ONColor
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EXAMPLE 2 : Assembly steps
3 TAPER PIN, Steel, 1 REQD.
2 SHAFT, Steel, 1 REQD.
1 SUPPORT, Steel, 1 REQD.
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EXAMPLE : Section line practice
A B
Good Poor
Which is an appropriatefull section view of thisassembly ?
C D
OFF ON
Color
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EXAMPLE 3 : Assembly steps
3 PIN, Steel, 1 REQD.
2 ARM, Steel, 1 REQD.
1 CLEVIS, Steel, 1 REQD.
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EXAMPLE : Section line practice
A
B
Good Poor
OFF ONColor
Which is an appropriate
section view of the joint ?
C
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LEADER LINE PRACTICE
Drawn in the ob l ique direction.
Drawn from the inside of the part to the balloon
and placed a filled circle at the beginning of a line.
12
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Shaft
Housing
Bearing
Coverplate
Capscrew
EXAMPLE
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1. Assemble steps.
2. Function of each part in machine.
3. Design concept.
INTERPRETING ASSEMBLYDRAWING
EXAMPLE 1 S h f hi h i
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EXAMPLE 1 : S haft support on a machine housing
Assemble steps
1. Install bearing to the shaft.
2. Install the bearing-shaft unit to
the housing.
3. Install the cover plate.
4. Tighten the screw.
EXAMPLE 1 S h f hi h i
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1. B earing :
Support the rotating shaft.
2. Cov er :- Control an axial movement.
- Prevent the bearing unit from
rotation.
Functions of main parts
EXAMPLE 1 : S haft support on a machine housing
EXAMPLE 1 S h f hi h i
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Av o i d direct contact between
rotating shaft and housing as well
as cover plate by using a bearingand clearance holes.
EXAMPLE 1 : S haft support on a machine housing
Design concept
EXAMPLE 2 L k i i
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1. Wrap a packing to the shaft.
2. Install studs to the casing.
3. Install the gland ring where its
holes align with stud.
4. Place the washer and
tightening the nut.
PackingCasing
Gland
EXAMPLE 2 : Leakage prevention unit
Assemble steps
EXAMPLE 2 L k ti it
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1. Pack ing :- Preventing the leakage of a
fluid inside the casing.
2. Gland :- Press the packing to make it
radial expand and press theshaft surface.
PackingCasing
Gland
EXAMPLE 2 : Leakage prevention unit
Function
EXAMPLE 2 L k g ti it
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Avoid direct contact between
rotating shaft and casing as well
as gland rings hole.
PackingCasing
Gland
EXAMPLE 2 : Leakage prevention unit
Design concept
EXAMPLE 3 Fi i g t h ft
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EXAMPLE 3 : Fixing parts on a shaft .
1. Place the keys on the
key seats.
2. Insert the parts to the
shaft until their surfaces
lean against the shoulder.
3. Insert collar and then pin
or retaining ring into the
groove.
Assemble steps
EXAMPLE 3 : Fi ing parts on a shaft
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EXAMPLE 3 : Fixing parts on a shaft .
1. K ey :
- Preventing rotational
movement of parts.
2. Pin and re tainin g r ing :
- Prevent axial movement
of parts on the shaft.
Function
EXAMPLE : Fixing parts on a shaft
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EXAMPLE : Fixing parts on a shaft .
Retaining ring can resist
lower axial force than collar
& pin unit.
Design concept
EXAMPLE : P arts with tapered holes on tapered shaft
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EXAMPLE : P arts with tapered holes on tapered shaft.
1. Insert the part on the
tapered end of the shaft.
2. Insert the washer(non-standard).
3. Tightening the nut.
Assemble steps
EXAMPLE : P arts with tapered holes on tapered shaft
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EXAMPLE : P arts with tapered holes on tapered shaft.
1. Wash er :
- Improve the distribution
the tightening force on
the part.
Function
EXAMPLE : P arts with tapered holes on tapered shaft
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EXAMPLE : P arts with tapered holes on tapered shaft.
Length of the tapered
portion and depth of the
tapered hole require acalculation.
Design concept
EXAMPLE : Parts having preloaded spring
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EXAMPLE : Parts having preloaded spring
1. Insert the spring into the casing.
2. Tighten the rod to the spring
loader.3. Close the cap and tighten.
Spring infree length
Assemble steps
EXAMPLE : Parts having preloaded spring
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EXAMPLE : Parts having preloaded spring
1. Spr ing p lun ger :
- Transmit a force from rod to
spring.
- Keep the spring in a position.
Function
EXAMPLE : Parts having preloaded spring
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EXAMPLE : Parts having preloaded spring
Spring plunger has a spherical
surface contacts to the cap;
therefore, the rod can align itself
to original position.
Design concept
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Mating o f Par ts
POINTS TO CONSIDER
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1. Surface finishing
2. Tolerance
- Size- Geometry
POINTS TO CONSIDER
SURFACE FINISHING
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SURFACE FINISHING
1. To control the accuracy in positioning and
tightness between mating parts .
2. To reduce the friction, especially for the part
moves relative to other parts.
Surface finishing means the quality of a surface.It relates to the level of roughness of a surface.
Purpose
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Surface Control Why do we need to control surface
characteristics?
Rough surfaces cause friction and wear It is difficult to make accurate measurements
from rough surfaces
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Surface Characteristics Roughness
Small hills and valleys found on a surface
Defined as the arithmetic average of the deviationsabove and below a mean height of a surface
Expressed in microinches or micrometers.
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Waviness
Surface irregularities greater than roughness
Expressed in inches or millimeters
Lay
Direction of tool marks on a machined surface.
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66 Autumn 2009
.25 inches.125 inSur face Cont ro l Sym bol
Material must be removed
Material must n o t be removed
Material removal not specified
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M
Parallel to line representing surface
Perpendicular to the line representing the surface
Both directions to the line representing the surface
Multidirectional marks
Circular
Radial
Lay particulate, non-directional, protuberant
C
R
P
Bar add ed
S y m b o lloca t ion
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24
Average roughness is 0.000024 inches, which isoften referred to as 24 microinches or inches.
Material must be removed.
2814
Maximum average roughness is 28 microinches.Minimum average roughness is 14 microinches.
Material must no t be removed.
45
R
Average roughness is 45 microinchesLines on the surface are radial with respect
to the center of the surface
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Assignment
You are to complete the drawing and thework sheets handed out.
They are due on