a 2002 yo-yo vs. a free gift guidelines to assembly design · 2017-12-28 · 1 2.008-spring-2004...
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2.008-spring-2004 S.Kim 1
2.008 Design & Manufacturing II
Spring 2004
Assembly & Joining
2.008-spring-2004 S.Kim 2
Dexter’s Plastic Can
-cool ?
-gas leakage ?
-recycling?
2.008-spring-2004 S.Kim 3
A 2002 Yo-Yo vs. a free gift
2.008-spring-2004 S.Kim 4
Guidelines to Assembly Design
Minimize partsDesign assembly process in a layered fashionConsider ease of part handlingUtilize optimum attachment methodsConsider ease of alignment and insertionAvoid design features that require adjustments
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Manufacturing
Unit Manufacturing
Processes
Assembly and Joining
Design forManufacture
MarketResearch
ConceptualDesign
Factory, Systems & Enterprise
•Welding•Bolting•Bonding•Soldering
•Machining•Injection molding•Casting•Stamping•Chemical vapor deposition
Contributions on the final cost?
2.008-spring-2004 S.Kim
J.Chun and http://www.lboro.ac.uk/departments/mm/research/product-
realisation/res_int/ipps/dfa1.htm 6
Cost of Design Changes
CONCEPT
DESIGN
X
10X
TOOLING
Assembly
100X
1000X
RELEASE
10,000X
$$$$ time
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Typical Cost Breakdown
Selling Price
Admin, sales24%
Profit19%
R&D5%
Manufacturing38%
Engineering14%
Manufacturing Costs
Direct labor12%
Parts, Material
50%Indirect labor26%
Plant Machinery
12%
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Assembly business
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Optical Connectors
Alignment errors
MT connector
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Initial Quality Study
IQS:
Problems experienced after 90 days of ownership per 100 vehicles
0 to 100, 100 to 200, 200 and over
2.008-spring-2004 S.Kim Sullivan, 1986 11
The automobile industry, 1980’s
SOP
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http://order.tupperware.com:8080/coe-images/items/10044822000_detail.jpg 12
Good Design DFMA (Design for Mfg. & Assembly)
Simplicity for both human operators and robotsEven Kids can do.
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2.008-spring-2004 S.Kim N. Suh 13
DFA guideSimplicity is the best DFA. Minimize part numbers, operations, simplify assembly sequence (steps) and set-upsStandardize components, use suppliable common partsMinimize assembly directions (layered structure)
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DFA guide (cont.)Modular design, product families, assembly friendiness
Use symmetrical partsPhysical integrationMinimize sharp, delicate, flexible, slippery part
Relax tolerances on non-critical locations.Approachable, line of sight
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DFA Guide (cont.)
Material for DFA, avoid flexible componentsConcurrent engineering
Design for disassembly (recycling, repair, retrofit)
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DFMA
Hitachi assemblability evaluation methodLucas DFABoothroyd-Dewhurst DFA (BD)
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Design for Assembly
0.10.20.30.40.50.60.70.80.91.0
024 8 4 2
Annual production volumes :robotic - 200,000automatic - 2,400,000
Ass
embl
y co
st ($
)
Number of parts
1) 2)
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Pneumatic Piston Sub-Assembly
screw
spring
piston
cover
piston stop
main block
Redesigned
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DFA: Examples
Part can jam when inserted into hole.
Tapering the hole facilitatespart insertion.
2.008-spring-2004 S.Kim Kalpakjian, Benhabib 20
DFA for Automation: Examples
Parts are difficult to assemble.
Chamfers assist assem bly.
Parts are difficult to align properly;
jamming can occur.
Changing part geometryallows it to be aligned properly
before it is released.
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Assembly automation
ChallengesParts Feeding
SortingOrienting
Pick-and-placeAssembly
PCB assembly?
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Non-vibratory Feeding
Groove
Rotary mechanism with multiple blades
Hopper
Rotation axisInclined discharge rail
2.008-spring-2004 S.Kim B. Benhabib 23
Vibratory Parts Feeding
Bowl
Outlet
Leaf springs
Base
Electromagnet
Track
Torsional vibration
Translational vibration
2.008-spring-2004 S.Kim B. Benhabib 24
Vibratory Feeding -orientation
Second attachment(rejects and )c d
Third attachment(orients and )e f
Discharge hole
Firstattachment(rejects and )a b
a
Side view
Top view
b c d e f
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Magnetic Parts Feeding
Parts picked up by magnets
Delivery chute
Magnets Parts
Stationary hopper
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DFA for Transporting
Non-functional pegprevents jamming.
Wider edge surfaceprevents overlap.Flat ends prevent jamming.
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Automated Assembly
TransferTransfer linesConveyorAutomated Guided Vehicle
PositionerAssembly Operations
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Transfer Lines
PistonStop
Work carriers Fixed rail
Step
Transfer railSlide
2.008-spring-2004 S.Kim B. Benhabib 29
Rotary Assembly Transfer
Completed pieces
Feedtrack
Vibratory bowl
Positioningunit Riveter
Inspectionstation
Adhesive-bondapplicator
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AGV
Pallet load / unload mechanism
WorkpiecePallet
Safeguards against collision
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Pick & Place Positioner
Linear actuator
Fixed-length arm
Rotary actuator
Rotary actuator
Gripper
Fixed base
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RobotArm
Wrist
Yaw
Pitch
Hydraulic/electric power unit
Robot controllerArm sweep
Elbow extension
Shoulder swivel
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Robots: Components
Manipulatorpositioningpowerstiffnesscontrol
End effectortooling
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Robots: Applications
3 D’s (Dull, Dirty, Dangerous)3 H’s (Hot, Heavy, Hazardous)
Materials handlingSpray paintingSpot weldingArc weldingAssembly
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Good Design Principles:DFM Assembly
Design parts to be self-locating and self-aligningError-proof parts to make incorrect assembly impossibleMinimize the number of parts.Minimize the number and variety tools for assemblyMinimize the number of axes of insertionEnsure clear vision and access for all assembly operationsMinimize the number and complexity of adjustmentsEliminate the need to hold down, clamp or fixture parts
Eliminate special assembly tools
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What assembly process to choose?
Reasons to avoid assemblyReasons that justify assembly
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Workholding
Immobilization of a workpiece for machining or assembly
Jigs: locating and holding workpiece, guiding toolsFixtures: locating and holding
Provide maximum accuracy and ease of mountingDatum
2.008-spring-2004 S.Kim B. Benhabib 38
3-2-1 rule of locating
6 dof, (Dx, Dy, Dz) and (Rx, Ry, Rz)3 support Points (1, 2 and 3) eliminate (Rx and Ry) and (-Dz); 2 points (4 and 5) eliminate (Rz) and (-Dx); and, 1 point (6) eliminates (-Dy).Push or clamp 3 directions, x,y,z.
X
Y
Z
Rx
Ry
Rz
Dz
Dy
Dx
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Direction of resultant clamping force
21 3