design for assembly - part of the design process 1988

8/18/2019 Design for Assembly - Part of the Design Process 1988

1/4

Design for Assembly Part of the Design Process

H. . Warnecke I ) , R. Bal3ler

Received on January

20,1988

Assembl y-ori ent ed pr oduct desi gn of f er s a great pot ent i al f or rati onal i za-

t i on. Assembl y cost s are an i mport ant f actor i n t he overal l costs of t he

product. Theref ore a speci f i c procedur e f or assembl y-ori ent ed pr oduct de-

si gn i s needed.

Beyond a short descr i pti on of wel l - known methods of desi gn f or assembl y

t hi s paper pr esent s an assembl y- ori ent ed desi gn process as a new devel o-

ped procedure.

Keywords

:

Assembly, Design. C Q s t Evaluation.

1 I nt roducti on

The i ncreasi ng pr essur e of nati onal and i nt ernat i onal

compet i t i on i s f orci ng f i rms t o rati onal i ze even

f urt her, especi al l y i n t he f i el d of assembl y. I n order

t o perf orm assembl y tasks w t h the l east possi bl e

expendi t ure of t i me, assembl y f aci l i t i es, space re-

qui r ement s and per sonnel , i t has become necessar y t o

i ncl ude these obj ecti ves i n the devel opment st age of

t he pr oduct . Theref ore, assembl y- ori ent ed desi gn now

pr ovi des a good opport uni t y f or rat i onal i zati on

/ I / .

Assembl y- ori ent ed product desi gn means t hat t he pr o-

duct s shoul d be desi gned i n such a way t hat expen-

di t ure on assembl y and product i on cost s are reduced to

a mni mum

/ 2 /

I gnor i ng t he techni cal aspect s of assembl y dur i ng t he

devel opment st age of t he product f r equentl y l eads to

costl y assembl y systems bei ng i nstal l ed. A r epr esen-

t ati ve sampl i ng carr i ed out f or t he German M ni st r y

of

Resear ch and Technol ogy

/3 /

showed t hat t he r equi r e-

ment s f or assembl y- or i ent ed product desi gn are not

t aken i nt o account suf f i ci ent l y dur i ng the desi gn

process. The same r epr esentat i ve sampl i ng al so con-

f i rmed thi s si t uati on w th r egard t o obst acl es t o

aut omat i on i n t he f i el d of assembl y, as shown by

f i gure

1.

I t i s f or t hese reasons t hat hol i sti c met hods are

needed for product desi gn sui t abl e f or assembl y:

methods whi ch can be i ntegrat ed i nto t he manufacturi ng

pr ocess ri ght f r omt he out set . The two most i nt er -

nat i onal l y wel l - known methods of Boot hroyd and

Dewhurst and of Hi t achi are t hus expl ai ned bel ow

af t er whi ch t he assembl y-ori ent ed desi gn

pr ocess devel oped at t he I PA i s presented.

2

Known Met hods f or Desi gn f or Assembl y

2.1 The Boothroyd and Dewhurst Method

Thi s method i s ai med at m ni m zi ng assembl y t i mes and

cost s f or exi sti ng products

or

pr oduct desi gns, by

m ni m zi ng the number of i ndi vi dual part s and op-

t i m zi ng t he desi gn of t he part s i n

so

f ar

as

concerns

handl i ng and j oi ni ng.

Thi s method i s i mpl ement ed i n t he st ages shown i n

f i gure

2 :

-

Choi ce of t he assembl y pr i nci pl e

-

Anal ysi s of t he assembl y tasks and

- I mprovement of t he desi gn.

Assembl y pri nci pl es ar e di f f erent i ated i nt o manual

assembl y, aut omat i c si ngl e pur pose assembl y, and

assembl y by i ndust r i al r obots. The assembl y t asks are

t hen anal ysed i n r el ati on t o the assembl y pr i nci pl e.

The handl i ng and j oi ni ng t i mes f or t he part s, and the

t heoreti cal m ni mumnumber of i ndi vi dual part s are

cal cul ated f or manual assembl y usi ng t wo spreadsheets .

For

aut omati c si ngl e pur pose assembl y, as wel l as

for

assembl y by i ndust r i al r obots, a tot al of

4

r

6

spreadsheet s ar e used

to

cal cul ate t he handl i ng and

j oi ni ng cost s and the t heoret i cal m ni mumnumber of

i ndi vi dual part s.

I n addi t i on t o the assembl y cost s, a desi gn ef f i ci ency

( DE) f act or

i s

cal cul ated i n respect

of

assembl y

sui t abi l i t y. The actual number of i ndi vi dual part s i s

mul t i pl i ed by t he actual assembl y t i mes

or

costs. Thi s

val ue i s t hen compar ed w t h the product made f r omt he

t heoreti cal m ni mum of i ndi vi dual part s, mul t i pl i ed by

t he assembl y t i mes or costs f or i ndi vi dual part s of

opt i mumdesi gn. Thus a

DE

f i gur e of between ( poor)

and 1 (i deal pr oduct desi gn sui t abl e f or assembl y) i s

obt ai ned.

The theoreti cal m ni mumnumber of i ndi vi dual par t s i s

det er m ned by consi der i ng t he f ol l ow ng quest i ons: -

. Must t wo component s whi ch ar e connected to each

other move rel at i ve t o each other duri ng t he per -

cept i on of t he pr oduct f uncti on?

. Must t wo component s whi ch ar e connect ed t o each

other be made of di f f erent mater i al s?

.

Must t wo component s whi ch ar e connect ed to each

ot her be separat ed dur i ng assembl y

or

di sassembl y

of

ot her component s

or

dur i ng percept i on of t he pr oduct

f unct i on?

Al most al l anal yti cal st eps i n the Boot hr oyd and

Dewhur st method ar e avai l abl e i n t he f orm of PC sof t -

ware. A r api d appl i cat i on of t he method i s t hus

possi bl e.

2. 2

The Hi t achi Method

Hi t achi devel oped i t s Assembl abi l i t y Eval uati on Method

( AEM) sever al year s ago, and has al r eady sol d i t t o

many f i rms. These f i r ms have sl i ght l y modi f i ed and

f ur t her devel oped t he met hod. Hi t achi i t sel f has

al r eady t aught t he method t o more t han 1500 desi gners

and pr oj ect engi neers i n tr ai ni ng cour ses and se-

mnars. I t i s est i mated t hat t he method has

so

far

achi eved resul t s amount i ng t o sever al m l l i on dol l ars.

The method i s based on t he use of i nst r ument s f or

quant i f yi ng t he sui t abi l i t y f or assembl y. The ant i ci -

pat ed assembl y cost s can be deduced; t he est i mat ed

cost s do not di f f erent i ate between manual and aut o-

mat i c assembl y. The pr ocedur e i s shown i n f i gur e

3 .

The r esearch team cal cul ates the j oi ni ng sequence w t h

t he hel p of draw ngs and sampl es or usi ng the com

pl et ed AEM f orms. As a resul t t he j oi ni ng pr ocess i s

deci ded upon and recor ded i n t he f orm of j oi ni ng

symbol s on the f orms. The i nt erpret ati on of t he f orms

i s achi eved usi ng compar at i ve t abl es and a f ormul a

val ue. The pr ocess gi ves t he val ue E f or t he assembl y

sui t abi l i t y and t he val ue K, whi ch gi ves t he est i mated

r el ati onshi p of t he assembl y cost s of a new pr oduct t o

that of an i ni ti al product.

I f t he val ues

E

and

K

were t o reveal a pr oduct t o be

unaccept abl e, t hen t he known weaknesses of t he product

woul d have to be i mproved. The actual product desi gn

i s t hen the r esponsi bi l i t y of t he desi gner, who must

seek out ways of r educi ng t he number of par t s and t he

j oi ni ng movement s.

3

I nf l uenci ng t he Desi gn Pr ocess

I n or der t o desi gn pr oduct s i n an assembl y-ori ent ed

manner , t he t echni cal r equi r ement s r egardi ng t he

assembl y of t he f i nal product need t o be known. Know-

l edge of t he requi r ement s, t he pr oduct mounti ng, t he

vari ous methods of i mpl ement i ng manual , par t l y

or

f ul l y automated assembl y syst ems must be avai l abl e at

t he devel opment st age of t he pr oduct and must be

i nt egr ated i nto t he product desi gn. The assembl y

process must be taken i nto consi der at i on when t he

pr oduct i s f i r st creat ed. Dur i ng the devel opment of

t he product , t he assembl y pr ocess must be anal ysed and

pl anned i n paral l el ( w t h a sl i ght t i me l ag) w th t he

desi gn. Onl y i n t hi s way can pr oduct s be desi gned f or

Anna ls

of

the

lRP Vol 37/1/1988


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si mpl e assembl y i n such a way as t o make f ul l use of

the pot ent i al f or rati onal i zat i on off ered by assembl y-

ori ent ed pr oduct desi gn / 4/ .

The t echni cal aspect s and r equi r ement s of t he assembl y

process must be consi der ed bef ore pl anni ng t he assem

bl y process i . e. bef ore the desi gn of t he pr oduct has

been compl eted. They shoul d be i ntegrat ed i nto t he

desi gn pr ocess as earl y as possi bl e. Those measur es

f or assembl y- ori ent ed pr oduct desi gn whi ch most af f ect

assembl y cost ( such as t he overal l mounti ng arr ange-

ment and t he subassembl i es) can onl y be successf ul l y

appl i ed when they ar e consi der ed at a very ear l y st age

of t he desi gn process.

The desi gn pr ocess i s di vi ded i nt o f our st ages

( pl anni ng, r ough desi gn, dr af t i ng and detai l ed desi gn)

/ 5 /

and t he needs f or assembl y- ori ent ed product

desi gn w l l vary w th di f f erent desi gn acti vi t i es.

I n order t o i nf l uence a desi gn pr ocess dur i ng i t s

di f f erent st ages, ai ds are r equi red. Some of t hese

ai ds ar e al r eady avai l abl e and some are par t l y used

f or di f f erent pur poses i n manuf act ur i ng practi ce.

However , some of t he ai ds essent i al f or t he appl i ca-

t i on of assembl y-ori ent ed product desi gn ei t her do not

yet exi st

or

ar e not pr operl y adapt ed t o t he pur pose.

I t i s vi tal that t he possi bi l i t i es for i nf l uenci ng the

sui t abi l i t y f or assembl y of t he desi gn be support ed by

t he ri ght ai ds at t he ri ght ti me. I n fi gure

4

t he ai ds

f or assembl y- ori ent ed pr oduct desi gn are l i st ed i n

accor dance w t h t he di f f erent desi gn stages.

4 Assembl y- or i ent ed Desi gn Process

The devel opment of t echni cal products i s car r i ed out

i n accordance w t h t he syst emati c desi gn procedures

descri bed i n

/5/.

I n order t o f ul f i l t he many r equi r e-

ment s made on a product , a great number of ai ds ar e

necessary. The t echni cal probl ems of assembl y must be

systemati cal l y i ncl uded i n t he convent i onal desi gn

process. On the one hand, t he necessary techni cal

r equi r ement s of assembl y are i ncl uded i n the desi gn of

t he pr oduct at var i ous st ages dur i ng t he desi gn pro-

cess. On t he ot her hand, t hi s causes i t erati ve l oops

dur i ng t he desi gn process. Al t hough t hese l oops become

more f r equent because of t he consi st ent appl i cati on of

ai ds, t hey are al so si gni f i cant l y short er . Thi s means

t hat at var i ous s t ages of t he assembl y- ori ent ed desi gn

process ther e w l l be the possi bi l i t y of checki ng t he

sui tabi l i ty for assembl y af ter rel ati vel y short i nter-

val s and, i f necessary,

of

maki ng t he appropr i ate

i mprovements.

I n

t hi s way i t i s possi bl e t o avoi d ti me

and ef f or t consumng product devel opment s whi ch mght

need t o be changed af t er t est i ng. Fi gur e

5

speci f i es

the al l ocati on of t he ai ds det ai l ed i n f i gur e 4 and

summari ses themf or an assembl y- or i ent ed desi gn pro-

cess

/2 / .

The assembl y- or i ent ed desi gn process shows t hat among

t he l arge number of appl i cabl e ai ds the most i mpor t ant

are the syst emati cal l y appl i ed desi gn r ul es and the

eval uat i on of t he sui t abi l i t y f or assembl y. Dur i ng the

var i ous st ages of t he desi gn pr ocess, di f f er ent r ul es

can i nf l uence t he pr oduct desi gn f r omt he techni cal

poi nt of vi ew of assembl y. Af t er compl eti ng each stage

of t he desi gn process, an eval uati on

of

i t s sui t abi l i -

ty f or assembl y i s necessary i n order t o determ ne if

t he desi gn needs t o be i mproved f or assembl y pur poses.

An assembl y-ori ent ed r evi eww l l pr ovi de i nf ormati on

on whi ch weak poi nts of a product must be i mproved

w th respect to i t s sui tabi l i ty f or assembl y.

Desi gn r ul es and t he eval uat i on of t he sui t abi l i t y f or

assembl y are dom nant among t he ai ds f or assembl y-

ori ent ed pr oduct desi gn. Ther ef ore, t hey w l l be

descri bed i n great er det ai l .

4. 1 Desi gn Rul es f or Assembl y-ori ent ed Product Desi gn

Desi gn r ul es repr esent a set of known and wel l - t r i ed

sol ut i ons f or cer t ai n desi gn t asks and can be con-

veni ent l y summari zed i n catal ogues. These cat al ogues

must meet cer t ai n general r equi r ement such as

:

-

qui ck, task- ori ented accessi bi l i ty

-

comprehensi ve r ange

of

sol uti ons

-

appl i cabi l i ty

to

convent i onal as wel l as to com

put er- ai ded desi gn /6/.

I n or der to f aci l i t at e usabi l i ty and to ensure f ast

access, t he cat al ogues must be sui t abl y cl assi f i ed i n

mai n and subsi di ary part s. These part s must r el aLe

Lo

t he st age

of

compl eti on and t he compl exi t y of t he

r ecor ded sol ut i ons. Thi s ki nd of cat al ogue st r uct ur e

has proved t o be more r eadi l y accepted by t he de-

si gners. I n t he devel oped catal ogue / 2/ the cl assi f i -

cat i on part

i s

di vi ded up i nt o

1

Measures f or t he product st r ucture

2 .

Measures f or subassembl i es

3 .

Measures f or i ndi vi dual components

4. Measur es f or j oi ni ng t echni ques.

I n t he mai n part of t hi s cat al ogue, t he act ual desi gn

rul es are l i sted i n det ai l , as shown by an extr act i n

f i gure 6 The access charact er i st i cs f or t hi s cat a-

l ogue are:

-

val i di t y of t he r ul es dur i ng the desi gn pr ocess

-

i mport ance of t he rul es ( A- , B- and C- rul es).

4 . 2

Eval uat i on of Sui tabi l i ty of Products f or

Assembl y

I n order t o eval uate the sui t abi l i ty of products f or

assembl y, i t i s necessary to consi der and eval uate al l

t he f actors of i nf l uence, i . e. the ent i r e spectr umof

assembl y- ori ent ed product desi gn.

The eval uat i on of t he sui t abi l i t y f or assembl y

of

pr oducts i n r el ati on t o the di f f erent st ages of t he

desi gn pr ocess requi r es t hat cruci al f act ors of i n-

f l uence be eval uated

/7 / .

Thi s can be achi eved usi ng

vari ous pri nci pl es. I n the case of t he assembl y-

ori ent ed desi gn pr ocess shown i n f i gur e 5 t he eval ua-

t i on a and b was car r i ed out w t h check l i st s whi ch

examne pr eci sel y t hose f actors whi ch are i mport ant

dur i ng t he var i ous st ages. AS f r omeval uati on C, t he

sui t abi l i t y f or assembl y can be eval uated w t h an

appr opr i ate procedure. The basi c i dea of t hi s pr oce-

dur e i s t hat t he pr oducts must be desi gned to f ul f i l

t he r equi r ement s and f unct i ons l i st ed on t he speci f i -

cat i on sheet . The pr oduct s ar e t hen assembl ed f rom

separ ate components and subassembl i es, each cont r i -

but i ng a share of t he t otal f unct i on of t he product:

t hi s assembl y met hod i nvol ves a cer t ai n ef f ort .

Accor di ng t o t he basi c pr i nci pl es of val ue anal ysi s

( det er m nati on of f uncti onal cost and f uncti onal

expendi t ure), t he rel ati on of t he f uncti onal cont ent

of a component t o t he r equi r ed assembl y expendi t ure

provi des one of t he cri t er i a f or assessi ng t he sui t a-

bi l i t y of an assembl y pr ocedur e. The eff i ci ency of an

assembl y procedure i s i mproved when component s w t h a

hi gh f unct i onal cont ent can be assembl ed w t h l ow

assembl y expendi t ure, compared t o cases where compo-

nent s w t h a l ow f uncti onal cont ent r equi r e a consi -

derabl e assembl y ef f ort .

TO carr y out such an eval uati on, t he f ol l ow ng st eps

are necessary:

1 t he sett i ng up of a funct i onal st r uct ur e

2 .

t he wei ghti ng of f unct i ons and t he det erm nat i on

of

3 .

t he sett i ng up of a subassembl y st r ucture

4 .

al l ocat i ng t he f uncti onal cont ent s to t he di f f er ent

5.

det erm nat i on of t he assembl y sequence

6. determ nat i on of assembl y expendi t ur e

7 . det er m nati on of val ues measur i ng t he sui t abi l i t y

f or assembl y

8

i dent i f i cat i on of t echni cal probl ems dur i ng assem

bl y.

t he f uncti onal cont ent

components

When usi ng conventi onal desi gn methods, a f unct i onal

st r uct ur e needs t o be creat ed. The f unct i onal cont ent

of t he di f f er ent f uncti onal uni t s can be deri ved f r om

thi s. Paral l el t o worki ng out t he det ai l s of t he

desi gn, t he subassembl y st r ucture can al so be est a-

bl i shed i n detai l ,

so

t hat i t becomes possi bl e to

al l ocat e the f uncti onal cont ent t o t he separ ate com

ponents and based on thi s, t o determ ne t he sequence

of assembl y. Al r eady dur i ng t he f i r st r ough desi gn, a

speci al l y devel oped pr ocedur e makes i t possi bl e t o

f i r st est i mate t he assembl y expendi t ure and t hen,

af t er f urt her detai l i ng of t he desi gn, t o determ ne i t

w t h gr eater preci si on. Wt h t he functi onal cont ent

det erm ned under poi nt

4

and t he corr espondi ng assem

bl y expendi t ure determ ned under poi nt

6,

t he val ue

f or t he sui t abi l i t y f or assembl y of t he respecti ve

assembl y procedure can be determ ned. AS a r esul t ,

compar abl e val ues of i ndi vi dual assembl y pr ocedures

are obt ai ned. The assembl y procedures w t h t he l owest

val ues are anal ysed f ur t her w t h t he hel p

of

a check-

l i st i n order t o i dent i f y t he act ual weak poi nt s of

t he techni cal aspects of assembl y. Thi s way, concr ete

pr oposal s f or a syst emati c r e-desi gni ng of t he weak

poi nt s can be worked out . Af t er t hi s r e-desi gn, t he

eval uati on of t he sui t abi l i t y f or assembl y may be

car r i ed out agai n,

Thi s pr ocedur e devel oped f or t he eval uati on of sui t a-

bi l i t y f or assembl y makes i t possi bl e to eval uate

di f f er ent product desi gns at di f f er ent st ages of

det ai l . Li nked t o the compl eti on st age of a pr oduct

desi gn, t he sui t abi l i t y f or assembl y can be repeat edl y

checked and i mproved as necessar y. Thi s cr eat es nume-

r ous shor t l oops i n t he desi gn pr ocess, as shown i n

2


3/4

f i gur e

5.

These shor t l oops r epresent an i t e ra t i ve

devel opment of assembl y- or i ent ed product s. Thereby

t he l a te recogn i t i on o f weak po i n ts and t he resu l t i ng

r epet i t i on of work can be avo i ded . The eval udt i on

procedure can be appl i ed r i ght up to t he f i nal st age

o f t he pr oduct des i gn ( eva l uat i on s t ep H) .

4.3 Appl i c at i o n of t he Assess ment Met hod

I n t h e l ef t - ha nd pa r t o f f i gur e

7

a concr et e exampl e

i s g i ven whi ch assess es t he assembl y processes Of an

assembl y i n

so

f ar a s conc er n s i t s s ui t a bi l i t y f o r

assembl y. The i t em zat i on of t he assembl y weak poi nts

was carr i ed out dur i ng the assembl y pr occoscs wi t h l ow

c ha r ac t e r i s t i c v al u es , i . e. t h ose deno t e d i n f i g ur e 7

by an ar r ow. These assembl y processes were t hen r e-

desi gned, and are r epr esent ed by t he val ues i n the

r i ght - hand par t

of

f i gur e 7. The appropr i a te des i gns

f r o m f i gur e 7 ar e compar ed i n f i gur e 8.

On the bas i s o f t he ana l ys i s o f t he assembl y p rocess ,

i t

was est abl i shed, by compar i ng t he funct i ons of t he

i ndi v i dual components and t he r esul t i ng assembl y

cost s , t hat t he or i gi nal des i gn shows a number o f

i ndi v i dual par t s, whi ch among ot her t h i ngs need t o be

a sse mbl e d i n di f f e r ent j o i n i ng di r e c t i o ns , e xhi bi t f c w

j o i ni ng ai d s , r e qu i r e addi t i o na l sec ur i ng d ev i c es a nd

expens i ve t ypes o f connec t i on, and exhi b i t f ew o rder

and h andl i ng c har a c t e r i s t i c s .

Based on these weak poi nt s t he act ual r e- desi gni ng was

under t aken, as can be seen on the r i ght - hand s i de o f

f i gur e

8.

The f o l l owi ng re - des i gni ng t asks were

c ar r i e d o ut :

-

The r epl acement of t he spr ung shutt ers by cat ch

hooks and t he i ntegrat i on of t hese i nt o t he assembl y

housi ng ( no addi t i onal component s to be pr eassem

bl ed

) .

component housi ng ( so-ca1. l ed ext r uded f i l m)

t he r emova l o f t he shut t e r pro j ect i on.

be j o i n ed f r o m t op t o bot t om

-

The i n tegr a t i on o f t he bl i nd cover i ng i n to the

- ' The i mprovement of accessi bi l i t y at t he l ower end by

- The r a i s i ng o f t he p ropor t i on o f t he components t o

The new assessment of t he re- desi gn gave a s i gni f i cant.

i mprovement o f t he charac te r i s t i c va l ues f o r t he

sui t a bi l i t y f o r as se mbl y , a s c an be se en f r o m t he

compar i son i n f i gur e 8. W t h t h i s r e - de s i gn t h e i mp or -

t ant ass embl y weak poi nt s coul d be r emoved. F o u r of

t he wors t assembl y process es wer e abandoned and t hei r

f unct i ons were i n tegr a ted i nt o the hous i ng. The cha -

r a ct e r i s t i c val ue f or s u i t a bi l i t y f or a s s embl y o f t h e

overal l assembl y

hds

al most doubl ed dur i ng t he r e-

desi gni ng

to

1. 15. Thus i t was poss i bl e , wi t h respec t

t o assembl y, t o consi der abl y i mprove the assembl y by

t he del i bera te r e -des i gni ng o f t he weak poi n ts i dent i -

f

i ed.

T hi s a ct i o n sh ows , t h at p r e c i se anal y s i s o f t h e a ssem

bl y p rocess a t t he des i gn s t age i s ef f ec t i ve. A method

of assessment o f t he su i t abi l i t y fo r assembl y o f

product s

or

de s i g ns i s a pr e r e qui s i t e f o r d i s c ov er i ng

and r emovi ng weak poi nts . Thi s met hod of ass ess ment

was devel oped wi t h t he ai d of comput er s and used on

PCs

so t hat t he work st ages 1 - 7 of t he ni et. hod ca n

bc rapi dl y execut ed on a comput er. A ver y rapi d

pur pose f ul app l i ca t i on o f i ns t r ument s i s t hus r ender ed

pos s i bl e.

5

Prospects

An assembl y- or i ent ed desi gn pr ocess was devel oped, t ho

most i mpor t ant a i ds o f whi ch ar e ava i l abl e i n user -

or i ent ated, comput er- a i ded f orm At t he same t i me

i nst r ument s wer e devel oped whi ch can be used t o i nt e-

g r a t e t h e spe ci a l kno wl e dge of di f f e r ent o pe r a t i o na l

a r ea s . T hi s p r o ce dur e i s t he pr e r e qui s i t e for a

success fu l company o rgani za t i on o f any f u tu r e i n te -

grat i on of product devel opment and assembl y p l anni ng.

The next st ep

i s

t h e i nt egr a t i o n o f t hi s pr o c ed ur e

i nt o a CAD sy s t e m ( pa r t i c ul a r l y t h e des i gn c at a l o gue ) .

The des i gner must be prepared t o take the sui t abi l i t y

f o r assembl y i nto account i n hi s desi gn work dur i ng

t he whol e desi gn process usi ng comput er a i ds.

The most i mpor t ant p re requ i s i t e f o r econom cal assem

bl y automat i on i s a ho l i s t i c p roduct des i gn based on

su i t abi l i t y f o r assembl y , wh i ch means , t hat aspec t s of

assembl y t echnol ogy must be bor ne i n m nd r i ght f r om

t he out se t o f t he des i gn pr ocess . Thi s is t he p re re -

qui s i t e f o r t he f ut ur e r e al i z at i on of t h e t o t a l r a -

t i o nal i z at i on po t e nt i al i n t h e ar e a of assembl y. Onl y

t he r at i onal assembl y of products can guarantee l ong-

t e r m i nt e r n at i onal c ompet i t i v i t y .

The i nst r ument s a l r eady aval l abl e f o r p roduct des i gn

based on sui t abi l i t y f o r assembl y must be f u r t her

devel oped and compl et ed

so

as t o become hol i s t i c

i nstr ument s

f or

produc t des i gn su i t abl e

for

produc-

t i o n. T he ai m i s t o de ve l o p i nt e gr a t ed sys t e ms f o r

p roduct des i gn su i t abl e fo r p roduc t i on, so a s t o f u l l y

r e al i z e t he pot e nt i al f or r at i onal i z at i on i n t he ar e a

of product manufact ure.

6

Ref erences

__

/ I / Abel e ,

E . :

Bai G er , R . ; Wo l f , E. , 1984, Anwendungs-

mbgl i chkei t en von f l exi bel aut omat i s i e r t en Mont a -

gesyst emen. Wur zbur g, Maschi nenmar kt , 90:31 - 32.

. - ~ ~r o duk t g es t a l t u ng n d zn K 0 ns t r u k t i o n sp : o z T

St ut t ga r t , Uni ver s i t a t , F ak ul t d t F er t i gungs t e ch-

ni k , Di s s . Dr . - I ng. Spr i nger V er l ag Ber l i n u. a.

/ 3 /

Abel e ,

E.:

Baf l l er , R. ; et al , 1984, Ei nsat zmbg-

/ 2 /

BaBl e r ,

t i .

1988.

I nt e r at i on der monta eger echt en

l i chkei t en von f l exi bel aut omat i s i e r t en Mont age-

sys t emen

.

i n de r i ndus t r i el l en P r o duk t i on,

VDI - Ver l a g Dussel dor f . ( S ch r i f t e nr e i h e Hu ma ni s i e -

r ung des Ar bei t s l ebens Band 61

~

/4/ Sc hr a f t , R. D. : Bai G er , R. , 1984, Pos si bi l i t i es t o

r eal i ze assembl y -o r i ent ed p roduct des i gn.

Proceedi ngs o f t he 5t h I CAA, Par i s .

/5/ N. N. ,

1977,

VDI - R i c ht l i ni e

2222,

Bl at t 1 ,

Konst r ukt i onsmethodi k, Konz i p i eren t echni scher

Produkte . Ber l i n, Co l ogne: Beut h -Ver l ag.

/6/ P ahl ,

G.;

Bei t z ,

M .

1986, Kons t r uk t i o ns l e hr e :

Handbuch f u r S tudi umund Prax i s , zwe i t e Auf l age .

Ber l i n , He i del berg , New Yor k , London, Par i s ,

Tokyo : Spr i nger Ver l ag.

/ 7 / Sc hr a f t , R. D. : BhBl er , R. ,

1986,

Mdgl i chkei t en zur

Umset zung des montageger echten Konst r ui er ens.

Tagung: Mont agegerechtes Konst r u i eren, 13t h/ 14t h

Mar ch

1986,

St u t t ga r t . VDI - Be r i c ht

592,

VDI - Ve r l a g, Dussel do r f .

0 crlmn mrc

to

1 5 5

f l r rnr

l - r t than one choice mswblcl

Fi gur e 1: Obst ac l es agai nst aut omati on i n

assembly-

or i ent ed product desi gn

F i gu r e 2 : Pr ocedure

of

t he Boot hr oyd Dewhurs t Met hod

3


4/4

Figure 3:

I

4.

FINAL DESIGN

Evaluation of the assembly suitability by Hitachi

Rules for assembly orlented product deslgn

Maasurrr for subalKernblles

Dtrlnn

of

the b a l k

uult

o.

2.3.1

2.3.2

2.3.3

Mounting

of

subassembl ies on the

ba sk uni t preferably complete

subassembly on one basic Unit)

Basic unit must have good

posltlonal stabil ity

Basic unit must have a preter-

A

B

B

117

i

1117

I

I

I

ably large and plane surface

Figure 6: Design rules for assembly-oriented product

design extract)

I\

I CREATIVE I CORRECTIVE

AIDS

FOR

ASSEMBLY

ORIENTED PRODUCT

: H

t a

n 5

B :

g g

1

STEPS IN THE DESIGN PROCESS

3

: :

1 PLANNING STAGE

1.1 recognlllon of requlrementa

1.2 deflnlllon of

t nnkn

2.2 creale lunctlonal structure

2.5

aelsct nrlnclnlan I I

2.6 prapnre solution vnrlnnla

3.1 drnf llng the maln functlonnl unlts

3.2 drnftlng the remdnlnp luncllonal unlts

3.7 annlyala

of

cost

recovery

3.8 draft comDIellon I

4.3

nnnlyala

of

producllon

data

1 PLANNING STAGE

1.1 rscognlllon

1

requr.m.n*

1.2

dsllnll lm 01

m a k s

4

1.3 create a reaulramenls 111

+

.2

crenle the IYnCllml~I lN C I U I O

-a

2.3 c r e a te m r l a l l o n s 01 the functlanal slmcture

a

EEL

-

__o

r .2

dralllng

the remalnlng luncllonal unlm +

~--+

+

.4

delermlne

i01~tl0ns

or each

luncl lon

4

2.5 se~octpflncwes

2.6

propt.re

aolutlon

varlsnta

+ .7 w o r k

oul

d l l l a r e n l concapls

.8 eve.baIe and solact Ihe dllleranl concept8

3.DRAFTING STAGE

3.1

dralllng Ihe

maln

luncllond u n h 4

Em

-

3.3 s ~ l s c l ullable parla

a1

Ihe droll

t

.4

de la l l ad design 1 the mnln snd auxl l lary luncllonal unlla - - - -

- .5 check and

Improva df8 l tn

3.6 r a ce

Iaulls

and problems

3 1

sna l ya l s

el coil recovery

:z

D 3.8 r l l l eomplallon

__o

3.9

declslon

on

droll

r

.1 dslalllnp

m

a

4.2 vork lng out spsclllcallona 4

4.3 analyds 01 prcducllon

dam

4.4 Inbase 10 DrOdYcllon

Legend wldelln.s and example cata log @ ~asombly-Drlorlly graph

colalog

of n la t lvs cost

a

alui ana ly i ls

valuation of sUItabll l ty tor issembly

~~

Figure 5: Assembly-oriented design process

Q

Figure

8:

Cornparision of t he d esigns

Figure 4: Aids for assembly-oriented product design

4

design for assembly - part of the design process 1988

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