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Design for Assembly Time estimation Design Rules Redesign

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Page 1: Assembly Short

Design for Assembly

Time estimation

Design Rules

Redesign

Page 2: Assembly Short

Time Estimation for Assembly

Handling pick up orient

Insertion location (obstructed view? Self locating?) hold down and resistance securing method

Page 3: Assembly Short

Symmetry

Handling Issues

36001809000β

360360901801800α Size Fragile/Sharp

Nest/TangleSlippery/Flexible

Page 4: Assembly Short

B-D Manual handling chart

Page 5: Assembly Short

Insertion Issues

Obstructed Access/View

AlignmentInsertion Force

Page 6: Assembly Short

B/D chart 2-2 first &second

B-D Manual insertion chart

Page 7: Assembly Short

1 – screw(2) (steel)not easy to align

2 – cover(steel) not easy toalign – assembly worker’sfingers must be used toalign edges3 – spring(steel) (closed ends)

subject to continuous cycling andmust be spring steel

4 – piston stop(plastic)edge is chamfered for easeof alignment5 – piston(aluminum) obstructed

access for insertion of spindle intobottom of bore

6 – main block(plastic)depth of bore is 28mmwith small through hole forpiston spindle

Pneumatic PistonSub-Assembly

Page 8: Assembly Short

B-D Manual handling chart

piston

screws coverspring

Page 9: Assembly Short

B-D Manual insertion chart A

coverpiston

spring

Page 10: Assembly Short

B-D Manual insertion chart B

screws

Page 11: Assembly Short

Pneumatic Piston Sub-Assembly

1 2 3 4 5 6 7 8 9 Name of Assembly

Pa

rt I

.D.

No

.

nu

mb

er

of

tim

es t

he

opera

tion is c

arr

ied

ou

t co

nse

cu

tive

ly

two-d

igit m

anual

handlin

g c

ode

manual handlin

g

tim

e p

er

pa

rt

two-d

igit m

anual

insert

ion c

ode

manual in

sert

ion

tim

e p

er

pa

rt

op

era

tio

n t

ime

,

seconds

(2)*

[(4)+

(6)]

opera

tion c

ost,

cents

0.4

*(7)

fig

ure

s f

or

estim

atio

n o

f

the

ore

tica

l m

inim

um

part

s PNEUMATIC

PISTON

6 1 30 1.95 00 1.50 3.45 1.38 1 MAIN BLOCK

5 1 10 1.50 10 4.00 5.50 2.20 1 PISTON

4 1 10 1.50 00 1.50 3.00 1.20 1 PISTON STOP

3 1 05 1.84 00 1.50 3.34 1.34 1 SPRING

2 1 23 2.36 08 6.50 8.86 3.54 0 COVER

1 2 11 1.80 39 8.00 19.60 7.84 0 SCREW

43.75 17.50 4 design efficiency 0.27

TM CM NM = (3*NM)/TM

Page 12: Assembly Short

Boothroyd/Dewhurst Design Rules

Reduce part count and part typesStrive to eliminate adjustmentsDesign parts to be self-aligning and self-locatingEnsure adequate access and unrestricted visionEnsure the ease of handling of parts from bulkMinimize the need for reorientations during

assemblyDesign parts that cannot be installed incorrectlyMaximize part symmetry if possible or make parts

obviously asymmetrical

Page 13: Assembly Short

Rules to reduce part count

During operation of the product, does the partmove relative to all other parts already assembled?

Only gross motion should be considered – small motionsthat can be accommodated by elastic hinges, for example,are not sufficient for a positive answer

Must the part be of a different material than or beisolated from all other parts already assembled?

Only fundamental reasons concerned with materialproperties are acceptable

Must the part be separate from all other partsalready assembled because otherwise necessaryassembly or disassembly of other separate partswould be impossible?

Page 14: Assembly Short

1 – snap on cover andstop (plastic)

2 – spring(steel)

3 – piston(aluminum)

4 – main block(plastic)

Redesign:Pneumatic PistonSub-Assembly

Page 15: Assembly Short

Re-design

1 2 3 4 5 6 7 8 9 Name of Assembly

Pa

rt I

.D.

No

.

nu

mb

er

of

tim

es t

he

opera

tion is c

arr

ied

ou

t co

nse

cu

tive

ly

two-d

igit m

anual

handlin

g c

ode

manual handlin

g

tim

e p

er

pa

rt

two-d

igit m

anual

insert

ion c

ode

manual in

sert

ion

tim

e p

er

pa

rt

op

era

tio

n t

ime

,

seconds

(2)*

[(4)+

(6)]

opera

tion c

ost,

cents

0.4

*(7)

fig

ure

s f

or

estim

atio

n o

f

the

ore

tica

l m

inim

um

part

s

PNEUMATIC

PISTON

(re-design)

4 1 30 1.95 00 1.50 3.45 1.38 1 MAIN BLOCK

3 1 10 1.50 00 1.50 3.00 1.20 1 PISTON

1 1 05 1.84 00 1.50 3.34 1.34 1 SPRING

2 1 10 1.50 30 2.00 3.50 1.40 1 COVER & STOP

13.29 5.32 4 design efficiency 0.90

TM CM NM = (3*NM)/TM

Page 16: Assembly Short

See master mechanic electric screw driver