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2.008 Design & Manufacturing II Spring 2004 Assembly & Joining. 2.008-spring-2004 S.Kim . 1. Dexter ’ s Plastic Can. -cool ? -gas leakage ? -recycling?.

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slide1

2.008 Design & Manufacturing

II

Spring 2004

Assembly & Joining

2.008-spring-2004

S.Kim

1

slide2

Dexter’s Plastic Can

-cool ?

-gas leakage ?

-recycling?

2.008-spring-2004 S.Kim 2

slide3

A 2002 Yo-Yo vs. a free gift

2.008-spring-2004 S.Kim 3

slide4

Guidelines to Assembly Design

Minimize parts

Design assembly process in a layered fashion

Consider ease of part handling

Utilize optimum attachment methods

Consider ease of alignment and insertion

Avoid design features that require adjustments

2.008-spring-2004 S.Kim 4

slide5

Manufacturing

Market

Research

Conceptual

Design

Contributions on the final cost?

Unit

Manufacturing

Processes

Assembly and

Joining

•Machining

•Injection molding

•Casting

•Stamping

•Chemical vapor

deposition

•Welding

•Bolting

•Bonding

•Soldering

Factory,

Systems &

Enterprise

2.008-spring-2004 S.Kim 5

slide6

Cost of Design Changes

time

J.Chun and

http://www.lboro.ac.uk/departments/mm/research/product-

realisation/res_int/ipps/dfa1.htm

2.008-spring-2004 S.Kim 6

slide7

Typical Cost Breakdown

Selling Price

Engineering

14%

R&D

5%

Manufacturing Costs

Plant

Admin, sales

Machinery

24%

12%

Manufacturing

38%

Parts,

Material

50%

Indirect

labor

26%

Profit

19%

Direct

labor

12%

2.008-spring-2004 S.Kim 7

slide8

Assembly business

Industry % Workers in Assembly

Automobile

Aircraft

Telephone & Telegraph

Farm Machinery

Home appliances

Two-wheel vehicles

M. Culpepper

2.008-spring-2004 S.Kim 8

slide9

Optical Connectors

MT connector

Alignment errors

2.008-spring-2004 S.Kim 9

slide10

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 10

slide11

The automobile industry, 1980’s

Problem “fine and fix”

Product Launch

(US company)

Problem prevention

(Japanese company)

Design Changes per Week

SOP

Months Relative to Product Launch

Sullivan, 1986

2.008-spring-2004 S.Kim 11

slide12

Good Design

DFMA (Design for Mfg. & Assembly)

Simplicity for both human operators and robots

Even Kids can do.

http://order.tupperware.com:8080/coe-

images/items/10044822000_detail.jpg

2.008-spring-2004 S.Kim 12

slide13

DFA guide

Simplicity is the best DFA. Minimize part numbers,

operations, simplify assembly sequence (steps) and

set-ups

 Standardize components, use suppliable common

parts

 Minimize assembly directions (layered structure)

Figure 3.3. Can and bottle opener. This bottle/can opener satisfies two FRs: (1) opens cans,

and (2) opens bottles. If the requirement is not to perform these two functions simul-

taneously, then this physically integrated device satisfies two independent FRs.

N. Suh

2.008-spring-2004 S.Kim 13

slide14

DFA guide (cont.)

Modular design, product families, assembly

friendiness

Use symmetrical parts

Physical integration

Minimize sharp, delicate, flexible, slippery part

Relax tolerances on non-critical locations.

Approachable, line of sight

Fragile/Sharp

Symmetry

Size

Slippery/Flexible

2.008-spring-2004 S.Kim 14

slide15

DFA Guide (cont.)

Material for DFA, avoid flexible components

Concurrent engineering

Design for disassembly (recycling, repair,

retrofit)

2.008-spring-2004 S.Kim 15

slide16

DFMA

Hitachi assemblability evaluation method

Lucas DFA

 Boothroyd-Dewhurst DFA (BD)

2.008-spring-2004 S.Kim 16

slide17

Design for Assembly

Number of parts

2.008-spring-2004 S.Kim 17

slide18

Pneumatic Piston Sub-Assembly

screw

1 – snap on cover and

stop (plastic)

cover

spring

2 – spring(steel)

3 – piston

(aluminum)

piston stop

piston

4 – main block

(plastic)

main block

Redesigned

T. Gutowski

2.008-spring-2004 S.Kim 18

slide19

DFA: Examples

Pa rt ca n jam when Tape ring the hol e

inserted into hole . facilitates part insertion.

Alignment

2.008-spring-2004 S.Kim 19

slide20

DFA for Automation: Examples

Parts are difficultChanging part geometry

to align properly; allows it to be aligned properly

jamming can occur. before it is released.

Parts are difficult Chamfers assist

to assemble . assem bly.

2.008-spring-2004 S.Kim 20

Kalpakjian, Benhabib

slide21

Assembly automation

Challenges

Parts Feeding

Sorting

Orienting

 Pick-and-place

Assembly

PCB assembly?

2.008-spring-2004 S.Kim 21

slide22

Non-vibratory Feeding

Rotary mechanism

with multiple blades

Groove

Hopper

Rotation axis

Inclined discharge rail

B. Benhabib

2.008-spring-2004 S.Kim 22

slide23

Vibratory Parts Feeding

Track

Outlet

Translational

vibration

Torsional

vibration

Bowl

Electromagnet

Leaf springs

Base

2.008-spring-2004 S.Kim 23

B. Benhabib

slide24

Vibratory Feeding -orientation

Second attachment

(rejects c andd )

First

attachment

(rejects a and b )

Third attachment

(orients e and f )

Discharge hole

Side view

Top view

2.008-spring-2004 S.Kim 24

B. Benhabib

slide25

Magnetic Parts Feeding

Delivery chute

Parts picked up

by magnets

Stationary

hopper

Magnets

Parts

2.008-spring-2004 S.Kim 25

slide26

DFA for Transporting

Non-functional peg

prevents jamming.

Wider edge surface

prevents overlap.

Flat ends prevent jamming.

2.008-spring-2004 S.Kim 26

B. Benhabib

slide27

Automated Assembly

  • Transfer
    • Transfer lines
    • Conveyor
    • Automated Guided Vehicle
  • Positioner
  • Assembly Operations

2.008-spring-2004 S.Kim 27

slide28

Transfer Lines

Work carriers

Fixed rail

Stop

Step

Piston

Transfer rail

Slide

2.008-spring-2004 S.Kim 28

slide29

Rotary Assembly Transfer

Positioning

unit

Riveter

Feedtrack

Vibratory

bowl

Adhesive-bond

applicator

Completed

pieces

Inspection

station

2.008-spring-2004 S.Kim 29

B. Benhabib

slide30

AGV

Workpiece

Pallet load / unload

mechanism

Pallet

Safeguards

against collision

2.008-spring-2004 S.Kim 30

slide31

Pick & Place Positioner

  • Fixed-length arm
    • Linear actuator
  • Rotary actuator
  • Gripper

Rotary actuator

Fixed base

2.008-spring-2004 S.Kim 31

slide32

Robot

Arm

Elbow extension

Hydraulic/electric power unit

Shoulder

swivel

Yaw

Wrist

Arm sweep

Robot controller

Pitch

2.008-spring-2004 S.Kim 32

slide33

Robots: Components

  • Manipulator
    • positioning
    • power
    • stiffness
    • control
  • End effector
    • tooling

2.008-spring-2004 S.Kim 33

slide34

Robots: Applications

  • 3 D’s (Dull, Dirty, Dangerous)
  • 3 H’s (Hot, Heavy, Hazardous)
    • Materials handling
    • Spray painting
    • Spot welding
    • Arc welding
    • Assembly

2.008-spring-2004 S.Kim 34

J. Chun

slide35

Good Design Principles:

DFM Assembly

  • Design parts to be self-locating and self-aligning
  • Error-proof parts to make incorrect assembly impossible
  • Minimize the number of parts.
  • Minimize the number and variety tools for assembly
  • Minimize the number of axes of insertion
  • Ensure clear vision and access for all assembly operations
  • Minimize the number and complexity of adjustments
  • Eliminate the need to hold down, clamp or fixture parts
    • Eliminate special assembly tools

Alignment

2.008-spring-2004 S.Kim 35

slide36

What assembly process to choose?

Reasons to avoid assembly

Reasons that justify assembly

2.008-spring-2004 S.Kim 36

slide37

Workholding

  • Immobilization of a workpiece for machining
  • or assembly
    • Jigs: locating and holding workpiece, guiding tools
    • Fixtures: locating and holding
  • Provide maximum accuracy and ease of
  • mounting
  •  Datum

2.008-spring-2004 S.Kim 37

slide38

3-2-1 rule of locating

6 dof, (Dx,Dy,Dz) and (Rx,Ry,Rz)

3 support Points (1, 2 and 3) eliminate (Rxand 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.

Direction of

resultant clamping

force

2.008-spring-2004 S.Kim 38

B. Benhabib