design process and engineering drawing
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ME 240
INTRODUCTION TO DESIGN ANDMANUFACTURING
DESIGN PROCESS
AND
ENGINEERING DRAWING
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Steps in the Design Process
Conceptual Design
Detail Design
Preliminary Design
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Preliminary (Embodiment) Design
Prel iminary design is that part of the design p rocess in which,
st ar ti ng from t he concep t o f a technical product, the design i sdeveloped, in accordance with technical and economic criteria to
the point where subsequen t detail design can lead d irectl y to
manufacturing
General objectives:
Fulfillment of technical function
Economic feasibility
Individual and environmental safety
Governing rules:
Clarity Simplicity
Safety
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Preliminary (Embodiment) Design
Principles of Embodiment Design:
Principles of force transmission
Flowlines of force; Uniform strength; short force transmission path; Matched
deformations; etc.
Principle of the division of tasks
Assignment of sub-functions;
Principle of self-help
Self reinforcing solutions; Self balancing; Self protection; etc
Etc.
Methods/Guidelines for Embodiment Design:
Design for X
X = Strength; Deformation; Creep & relaxation; Corrosion; Production; Etc.
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Detail Design
Steps of Detail Design:
Finalizing the definitive layout
Integration of individual components into assemblies
Completion of production documents
Detai l des ign is that par t o f the des ign process which completes the
preliminary/embodiment design with final instructions and informationabout the layout, form, dimensions and surface properties of all
individual components, the def ini tive selection of materials and a f inal
scrutiny of the manufacturing methods and costs.
The most impor tant aspect o f detai l design is the preparat ion of the
production documents and especially of detailed component drawings,
of assembly drawings and of parts l ists (BOMs).
We will focus now on the rules, techniques and methods of
developing detailed component drawings and specifications.
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Example of an Engineering DrawingDimensioned according to ANSI
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Projections
3-D Projections:
Multiview Projections:
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Projections
Projection
Plane
Projection
Plane
View
Point
Perspective
Projection
Orthographic
Projection
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Third Angle Projection
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Standard Views in Third Angle Projection
Preferred
Views
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First Angle Projection
Preferred
Views
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First and Third Angle ProjectionSummary of standard use and symbols:
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Auxiliary Views
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Sections and Detail Views
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Representation of Threaded Features
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Sheet Layout
ANSI s izes
A 8.50” x 11.00”
B 11.00” x 17.00”
C 17.00” x 22.00”
Etc.Title block
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ASSEMBLY DRAWING
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PART DRAWINGS
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Line Usage
EXAMPLE:
Extension (witness) line
Visible line
Hidden line
Center line
Dimension
line
25
Leader line
Outlines, edges of p lanes, etc.
Hidden lines
Center lines (axes of rotation)
Dimension lines
25
25 }
Witness and leader lines
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Dimension PlacementSome impor tant rules:
Dimension lines should lie outside of the outline of the part
whenever possib le
Dimension lines should not cross one another
Dimensions should be included on a view that shows the true
length of the feature
Each feature should be dimensioned only once
Dimension lines should be aligned or grouped to promote
clarity whenever possible
The numerical dimensions and arrows should be placed
between the extension lines where space permits
Dimensions should be no closer than about 10 mm from the
object’s outline
Dimensions should be placed in clear spaces, as close as
possible to the feature they describe
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Dimension Placement
Some important rules (continued):
Extension lines may cross visible lines of the object
Dimension lines and extension l ines should not cross, if
possible.
Extension lines may cross other extension lines
A center l ine may be extended to serve as an extension l ine
Centerlines should not extend from view to view
Leader lines are usually sloped at about 30, 45, or 60 degrees
and are never horizontal or vertical
There should be no redundant dimensions
Dimensions related to function or manufacturing should be
given
Numerical values of dimensions should be centered between
arrowheads Numerical values of dimensions should be standard values i f
possible
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Dimension PlacementExamples of correct and incorrect use:
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Dimension Placement
Examples of correct and incorrect use:
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Dimension PlacementExamples of correct and incorrect use:
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Dimension Placement
Examples of correct and incorrect use:
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Dimension PlacementExamples of correct and incorrect use:
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A Complete Engineering Drawing
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EXAMPLE
6
8
4
3
3
3
6
2
415R
3
Incorrect Drawing
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EXAMPLE
68
4
3
3
6
R15
4
6
3
Improved Drawing
(Incomplete)
6
8
4
3
3
3
6
2
415R
3
Incorrect Drawing6
8
4
3
3
3
6
2
415R
3
Incorrect Drawing