get130: engineering technology fall 2016jsumey/cet490/n08-designrepresentation.pdfget130: intro to...
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GET130: Intro to Engineering Technology Fall 2016
Design Representation 1
GET130 Intro to Engineering TechnologyFall 2016
Once a design is conceptualized, it must be representedand communicated to others in a complete and technically accurate fashion.
Communication methods:• oral presentations• written documents• technical drawings• demonstration of model / prototype
Different engineering fields use different types of representations and symbology.• and tools (software packages) to work with them
symbology, def: a system of symbols†
† www.merriam-webster.com2
sketch: generally refers to a freehand drawing• including artistic implications
• subjective/ambiguous impressions• like you did in the problem solving lab
drawing: result of using drawing instruments or technology• ruler/compass• drafting board• computer with CADD software
CADD: Computer Aided Design and Drafting
3
civil• grading, landscaping, etc.• topological & relief maps
architectural• plan, section, elevation, perspective• http://blog.visual.ly/visualization-in-architecture-drawing-types/
construction• electrical, mechanical (HVAC), plumbing
patent• http://www.uspto.gov/patents/ General Info Drawing Standards
engineering• clearly defines requirements for engineered items…
4
block diagram computer/software engineering:
• flowchart electrical engineering:
• schematic mechanical:
• layout• part/detail• assembly / exploded view• arrangement
bill of materials (BOM)
5
high-level presentation of a system to show overall concepts without implementation details• aka system diagram• used in all engineering fields
symbology:• blocks – denote principle parts or functions of the system• lines – show relationships between the blocks
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GET130: Intro to Engineering Technology Fall 2016
Design Representation 2
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a visual diagram tool that shows the sequencing of a process or algorithm to solve a specified problem
typically used to design/document/analyze computer programs, program flowchart
symbology:• blocks – describe the steps to be performed• lines – show the order of the process
how it works…
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Alternate process(entry)
Process
Predefined process(subroutine)
On-page connector
Off-page connector
Decision
Data input/output
Terminator
• a good (free) diagramming tool: Diagram Designer
GET130: Intro to Engineering Technology Fall 2016
Design Representation 3
Scenario:
You jump in your car, hit the key, but your car won’t start.
What to do?
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car won't start
willkey turn
?
put car in park
doesengine crank
?check battery
batterygood
?
NN
N
N
Y
Y
replace battery
gotgas?
get gas!N
is carin park
?
Y
Y
Y
callservice
technician
carstart now
?
done,be happy
Y
N
done,pay da man
A
A
from the flowchart given, determine the output of x, y, and i
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START
i=0x=10y=1
x > y?
x=x/y
y=y+i
i=i+1
Outputi,x,y STOP
N
Y
x y ix y i10 1 0x y i
10 1 010 1 1
x y i10 1 010 1 110 2 2
x y i10 1 010 1 110 2 25 4 3
x y i10 1 010 1 110 2 25 4 3
1.25 7 4
an abstract representation of a system using an appropriate symbology
heavily used in electronics (but not only!)• aka circuit diagram
Electronic Design Automation (EDA) computer tools provide for schematic capture and editing◦ ex: National Insruments’ Multisim
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audio power meter:
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7-segment display†:
† this schematic done in Multisim
GET130: Intro to Engineering Technology Fall 2016
Design Representation 4
a really nice table of electrical and electronic symbols may be found at RapidTables.com• http://www.rapidtables.com/electric/electrical_symbols.htm
they also have another table of some electronic components with photos!• http://www.rapidtables.com/electric/Electronic_components.htm
another library of 800+ electronic symbols & photos:• http://www.electronic-symbols.com/
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include:
are drawn in conformance to industry standards• ex: ASME Y14.24 drawing standards Table of Contents
• required by Department of Defense (DoD) policies
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• layout • modify• detail • control• assembly • interface• installation • mechanical schematic• arrangement • electrical schematic
shows design requirements of major system components via pictorial, notational, and dimensional data
used during development to prepare other engineering drawings
not typically used for fabrication
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click drawing to open PDF
provides complete definition of the part or parts shown including dimensioning and tolerances, also identifies the parts
includes materials and fabrication info
may be either for a single part (monodetaildrawing) or multiple parts (multidetail)
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GET130: Intro to Engineering Technology Fall 2016
Design Representation 5
Notice: dimensioning tolerances title block identification
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shows how individual parts fit together to form an assembly
may be in the form of an exploded view
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depicts the physical relationship of significant components using appropriate projections or perspective views
may include reference dimensions, but not item identification info
used to convey general description of the configuration and location of significant items, i.e. ancillary info
not normally used to control design
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GET130: Intro to Engineering Technology Fall 2016
Design Representation 6
sank 11/01/1995 off Palungitak Island in northern Newfoundland due to “loss of situational awareness”
3 crew members lost
1 survivor paddled 2 hours to shore
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in technical drawings, various views are used to describe an object or item
these views basically fall into two categories:• Isometric (pictorial)• Orthographic (plan)
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shows 3 surfaces of an object in a 2D fashion
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• perspective view – attempts to replicate what is seen by human eye or camera
• lines of depth converge to one or two vanishing points on an imaginary horizon
• most complex but most accurate
• isometric view – uses only vertical and 30º lines to “simulate” perspective
• easy to create and widely used
• supported by CAD tools
illustrates a 3D object via 2D views of two or more of the object surfaces
“a collection of views of an object formed by projectors onto and perpendicular to the desired plane of projection”• in English please???
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projection onto the frontal plane
projection onto the horizontal plane
projection onto the profile plane
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envision the object contained in a glass box wrapped with paper
each of the 6 sides shows its unique projection
cut & unfold paper into its 2D form
all planes are hinged to the front plane, except for back which is hinged to left side
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GET130: Intro to Engineering Technology Fall 2016
Design Representation 7
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note that rarely do we need all 6 views• 3 views is typical, some objects need only 2• or even 1 as in the previous metal handle
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a system of standard symbology and conventions used on the detail drawing to convey maximal design details while keeping it neat and uncluttered
is a language of communication between designer and fabricator
based on ASME Y14.5 Dimensioning and Tolerancing standard
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essential components needed on every drawing to ensure correct interpretation• standard symbols for particular items• clear lettering (UPPERCASE only)• standard drawing views• clear consistent lines, dimensions & units• appropriate clarification notes• title block: drawing title designer/drawer’s initials & date material & finish specifications allowable tolerances (variations)
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metric dimensions include 0 before decimal point (0.5 mm); inch do not (.25 in)
line types:• extension lines – emanate from object with visible
separation gap• dimension lines – have break for the numbers, 10mm
from the object; 6mm for subsequent lines; shortest closest to object and longer lines further away
• leader lines – indicate surfaces & hole diameters; angled & pointing towards hole center
• hidden (dashed) lines – indicate a feature better seen in another view
• center lines (di-dashed) – indicate a cylinder object
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dimension lines
leader line
hidden line
cylinder line
extension lines
stacked dimensions
tolerance specifications
GET130: Intro to Engineering Technology Fall 2016
Design Representation 8
refers to allowable variation of a dimension• to accommodate imperfect manufacturing
processes• indicated with ± notation
specify only as tightly as needed• because tighter tolerances result in increased
manufacturing costs• and possibly use of more expensive equipment
tolerances are specified:• with a dimension line,• in a drawing note, or• in the title block as a drawing default
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from the ASME standard grouped by types
• form, profile, orientation, location, runout
ex: a piece thickness spec’d at .500±.003 in• it could vary between .497 - .503
in look for these in CADD
software!
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A bill of materials (BOM) is a list of the raw materials, sub-assemblies, intermediate assemblies, sub-components, parts and the quantities of each needed to manufacture an end product†.
used for communication between manufacturing partners (external BOM), or confined to a single manufacturing plant (internal BOM)
can be used in various contexts:• engineering BOM – design• electronics BOM – circuit board components• sales BOM – ordering/procurement/inventory• service BOM – maintenance
45† http://en.wikipedia.org/wiki/Bill_of_materials
BOMs can be created/maintained with• spreadsheet program (Excel)• purpose-built applications
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Diagram Designer• flowcharts, illustrations• http://logicnet.dk/DiagramDesigner
Autodesk Inventor Dassault Systems SolidWorks National Instruments Multisim◦ circuit schematics and PCB layout
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American Society of Mechanical Engineers (ASME)• https://www.asme.org/
“Engineering drawing”• http://en.wikipedia.org/wiki/Engineering_drawing
Engineering Drawing and Sketching [tutorial]• http://www.me.umn.edu/courses/me2011/handouts/drawing/blanco-tutorial.html
“Engineering Drawing Practices”◦ http://www.dtic.mil/ndia/2008technical/GastonEngineeringDrawingsY14_24a.pdf
“Flowchart”• http://en.wikipedia.org/wiki/Flowchart
GD&T Reference Guide• http://www.jus-rite.com/gdtguide.html
The United States Patent and Trademark Office (USPTO)• http://www.uspto.gov/patents/
Technical Drawing• http://machineshop.olin.edu/resources/documents/Technical%20Drawing%20-
%20Class%20Handout.pdf
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