UNIVERSITY OF PADUA
DEPARTMENT OF INDUSTRIAL ENGINEERING
MASTER COURSE IN ADVANCED MATERIALS SCIENCE AND
ENGINEERING
E alua ion o manu ac u ing p ocesses, ma e ials, and ene gy
e iciency in he I alian Eyewea Indus y: The po en ial o elec ic
hea ing me hods owa ds indus y 5.0
P o . Fab izio Dughie o
José Da id Be ancou h Mendoza
2102711
Academic yea 2023/2024
1
1 Index
Summa y ...................................................................................................................... 3
In oduc ion .................................................................................................................. 4
1. I alian eyewea indus y ....................................................................................... 5
2. Ma e ials and manu ac u ing p ocesses o eyewea ............................................. 6
2.1 His o ic de elopmen o eyeglasses .............................................................. 6
2.2 Ma e ials used o eyeglasses ........................................................................ 6
2.2.1 Ma e ials used o eyeglasses lenses ...................................................... 6
2.2.2 Ma e ials used o me al ames ............................................................. 7
2.2.2.1 Monel (Ni-Cu alloy) ........................................................................... 7
2.2.2.2 Nickel ................................................................................................. 7
2.2.2.3 Nickel sil e ....................................................................................... 8
2.2.2.4 S ainless s eel ..................................................................................... 8
2.2.2.5 Ti anium.............................................................................................. 9
2.2.2.6 Aluminum ......................................................................................... 10
2.2.2.7 Be yllium and Cobal ....................................................................... 10
2.2.3 Ma e ials used o plas ic ames ......................................................... 11
2.2.3.1 Cellulose ace a e ............................................................................... 11
2.2.3.2 Cellulose p opiona e ......................................................................... 12
2.2.3.3 Polyca bona e ................................................................................... 13
2.2.3.4 Polyamide ......................................................................................... 13
2.3 Manu ac u ing p ocesses o eyeglasses ....................................................... 14
2.3.1 Me al eyeglasses manu ac u ing .............................................................. 15
2.3.1.1 Me allic emples ............................................................................... 16
2.3.1.2 Eye wi es .......................................................................................... 16
2.3.1.3 Finishing ........................................................................................... 16
2.3.2 Plas ic eyeglasses manu ac u ing............................................................. 17
2.3.3 Cellulose ace a e eyeglasses manu ac u ing ............................................ 18
2.3.3.1 CA F ame on s and emples ........................................................... 19
3. Elec ic hea ing heo e ical backg ound ............................................................. 20
3.1 Induc ion hea ing ......................................................................................... 21
3.1.1 Ma hema ical equa ions ....................................................................... 21
3.2 Dielec ic hea ing ........................................................................................ 23
2
3.2.1 Radio equency hea ing ....................................................................... 23
3.2.1.1 Ma hema ical equa ions .................................................................... 23
3.2.2 Mic owa es hea ing ............................................................................. 28
3.3 P ope ies o dielec ic ma e ials ................................................................. 30
3.3.1 Elec onic Pola iza ion ......................................................................... 30
3.3.2 Ionic Pola iza ion ................................................................................. 30
3.3.3 Dipola Pola iza ion ............................................................................. 30
3.3.4 Volume Pola iza ion ............................................................................. 31
4. Polyme ic dielec ic ma e ials ............................................................................ 32
4.1 Dielec ic p ope ies o polyme s ................................................................ 32
4.2 Cellulose ace a e (CA) as dielec ic polyme . ............................................. 33
5. Ene gy e iciency in Eu ope’s indus ies ........................................................... 34
6. Indus y 5.0 in Eu ope’s indus ies..................................................................... 35
7. Elec ic hea ing, and o he good p ac ices o be applied in he I alian eyewea
indus y owa ds Indus y 5.0 and sus ainabili y. ....................................................... 37
7.1 Elec ic hea ing o eyewea indus y .......................................................... 37
7.2 Bes A ailable Techniques o di e en sec o s ela ed o eyewea indus y ..
..................................................................................................................... 38
7.3 O he good p ac ices ound in li e a u e ...................................................... 39
7.4 Sus ainable Eyewea .................................................................................... 40
8. Conclusions ........................................................................................................ 43
Re e ences .................................................................................................................. 44
3
Summa y
Wi h he Eu opean Union’s (EU) goal o mode nize manu ac u ing p ocesses and
economic ac i i ies owa ds Indus y 5.0, he I alian eyewea indus y, enowned
globally o i s excellence and inno a ion, aces he challenge o adap ing o he
p inciples o a egene a i e, ci cula economy. This app oach emphasizes minimizing
was e, maximizing esou ce ci cula ion, and inc easing he use o enewable ene gy
and sus ainable ma e ials. This hesis s udies he cu en manu ac u ing p ocesses,
ma e ials, and ene gy e iciency wi hin he indus y, and explo es he po en ial o
elec ic hea ing me hods (induc ion, adio equency, and mic owa e) o enhance
ene gy e iciency, p oduc quali y and aceabili y. Pa icula a en ion is gi en o he
applica ion o mo e e icien hea ing echnologies and he ecen de elopmen o
sus ainable ma e ials. By e e encing he EU Re e ence Documen s on Bes A ailable
Techniques (BREFs) and ele an esea ch, his s udy aims o p o ide a amewo k o
he I alian eyewea indus y o imp o e p oduc i i y and achie e sus ainable
manu ac u ing p ac ices.
4
In oduc ion
The I alian eyewea indus y, a global leade enowned o i s inno a ion and
c a smanship, aces he challenges and oppo uni ies p esen ed by Indus y 5.0. The
Eu opean Union (EU) has se ambi ious goals o ans o m i s indus ial sec o s in o
mo e sus ainable, human-cen ic, and echnologically ad anced ope a ions. The shi
owa ds a egene a i e and ci cula economy, which emphasizes he minimiza ion o
was e, he maximiza ion o esou ce ci cula ion, and he inc eased use o enewable
ene gy and ma e ials.
In his con ex , he I alian eyewea indus y, adi ionally cha ac e ized by i s high
s anda ds o quali y and design, mus adap o hese new pa adigms o main ain i s
compe i i eness. This hesis in es iga es he cu en manu ac u ing p ocesses,
ma e ials, and ene gy e iciency wi hin he indus y wi h a speci ic ocus on how hese
elemen s can e ol e o mee he demands o Indus y 5.0 and sus ainabili y.
A key a ea o explo a ion is he po en ial o elec ic hea ing echnologies, pa icula ly
induc ion, adio equency, and mic owa e hea ing o enhance ene gy e iciency,
p oduc quali y, and aceabili y in eyewea p oduc ion. These me hods o e
signi ican ad an ages in e ms o p ecision, speed, and ene gy consump ion, making
hem a sui ed solu ion o he complex and di e se demands o mode n eyewea
manu ac u ing. The hesis also s udies he ecen de elopmen o mo e sus ainable
ma e ials, and p ac ices, which a e c i ical o aligning he indus y wi h he EU’s
en i onmen al and sus ainabili y goals.
Fu he mo e, he hesis e e ences he EU’s Re e ence Documen s on Bes A ailable
Techniques (BREFs) o p o ide a comp ehensi e amewo k o imp o ing
p oduc i i y and sus ainabili y in he eyewea indus y. By in eg a ing hese ad anced
hea ing echnologies and sus ainable p ac ices, he hesis aims o p esen a amewo k
o he indus y o achie e mo e e icien and en i onmen - iendly manu ac u ing
p ocesses, posi ioning i o long- e m esilience and g ow h in a apidly e ol ing
global ma ke .
5
1. I alian eyewea indus y
The op ical p oduc s indus y o igina ed in I aly, wi h Venice as i s epicen e , whe e
he i s eyeglasses we e p oduced in 1285 using ma e ials such as lea he , wood, and
me al o he use by he a is oc acy. The indus ial p oduc ion o eyeglasses also began
in I aly a he end o 19 h cen u y unde he leade ship o Angelo F escu a, an op ician
om Belluno, who de eloped he plas ic ames ha expanded he ange o s yles
a ailable. [1]
The eyewea indus y is one o he mos impo an indus ies in he no h-eas o I aly,
wi h he dis ic loca ed in Belluno being esponsible o he 80% o he coun y’s
p oduc ion. This indus y is known o he inno a ion applied in manu ac u ing
p ocesses and ma e ials, such as ligh weigh and du able componen s.[2]
The Belluno dis ic has expe ienced signi ican ans o ma ion since 1970, when he
companies Sa ilo and Luxo ica began hei pa ne ship wi h Gio gio A mani, wo king
oge he o combine ex e nal ashion expe ise wi h local manu ac u ing knowledge,
c ea ing p oduc s wi h s yle and quali y. This collabo a ion led o inno a ion and
e olu iona y changes in o he dis ic s, such as he Mon ebelluna dis ic , known o
spo swea , which is an example o combining ex e nal and in e nal knowledge wi h
esul s as he “plas ic e olu ion”.[3]
I alian companies lead he eyewea indus y, p oducing almos 25% o he wo ld’s
eyewea ames, p ima ily h ough small and medium-sized en e p ises concen a ed
in he Belluno dis ic . Companies such as Luxo ica, Sa ilo, De Rigo, and Ma colin
a e among he wo ld’s op en p oduce s, demons a ing I aly’s s eng h in he global
eyewea indus y.[4]
To summa ize he impo ance o he I alian eyewea indus y i can be said ha i is
he leading manu ac u e and expo e o sunglasses and ames in Eu ope, he second
la ges expo e o sunglasses and ames in he wo ld, and he leading manu ac u e
and expo e o sunglasses and ames in he high-end p oduc ange. App oxima ely
90% o i s p oduc ion is des ina ed o expo and o e 75% o i s u no e is de i ed
om he expo o i s p oduc s.[5]
6
2. Ma e ials and manu ac u ing p ocesses o eyewea
2.1 His o ic de elopmen o eyeglasses
The e olu ion o eyeglasses om i s scien i ic basis o hei cu en s a us as a ashion
accesso y da es back o he beginning o he 11 h cen u y when he Alhazen’s “Book
o Op ics”[6] i s desc ibed he ounda ion o oday’s op ics s udies. Then in he 13 h
cen u y, he i s ecognizable eyeglasses we e de eloped in I aly, p oducing ad ances
in bi ocals and as igma ism lenses wi h imp o ed unc ionali y.
Finally, in he 1970s, he ise o designe eyewea began, making eyeglasses a way o
exp ess pe sonal s yling, wi h inno a ions in bo h unc ionali y and design.[7]
2.2 Ma e ials used o eyeglasses
The i s ma e ials used as eyeglasses we e con ex qua s lenses su ounded by
oakwood ames, in en ed in Flo ence I aly in 13 h cen u y.[8]
2.2.1 Ma e ials used o eyeglasses lenses
Eyeglasses lenses we e made exclusi ely o glass un il he in oduc ion o polyme ic
o plas ic ma e ials. The i s polyme wi h good op ical p ope ies used was he
polyme ized me hyl me hac yla e (PMMA) hen an ac ylic esin made o allyl diglycol
ca bona e (now known as CR-39®).[9]
Glass being a highly anspa en ma e ial, chemical esis an , ha ing he p ope y o
no discolo wi h ime, and being ela i ely sc a ch- esis an was ideal o op ical use,
hen wi h he addi ion o alkaline me al oxides, he c ea ion o hinne lenses o high
e ac i e index and chemical esis ance was possible.[10]
Plas ic lenses made o polyme s wi h long-chain molecules, in e connec ing b anches,
and c osslinks p o ide g ea e lexibili y and be e impac esis ance han glass.
Ma e ials like polyca bona e and polyu e hane esins a e used o p oduce lowe densi y
and ligh weigh lenses.[9]
Hea ea men s like empe ing, a e used o educe de ec s, polish, and p e o m he
lenses, o be la e p essed and cooled.[11]
7
2.2.2 Ma e ials used o me al ames
Many ma e ials a e used o di e en pa s o he ames o he glasses, o example
o he nosepiece a ms and end pieces, he nickel is used because o i s s eng h and
abili y o be pliable, making his ma e ial sui able o pa s ha will be ben and
adjus ed.
2.2.2.1 Monel (Ni-Cu alloy)
Monel is an alloy o nickel and coppe . I is he mos common ma e ial used o c ea e
me al designs. Monel is a s ong, s able ma e ial ha can also be used o make nose
pads a ms, b idges, and end pieces. I is esis an o co osion and is economical o use
in he ame manu ac u ing p ocess.
Figu e 9 shows Monel eyeglasses.
Figu e 9 Monel eyeglasses.
1
2.2.2.2 Nickel
Nickel is a s ong elemen ha gene ally bends wi hou b eaking, making i sui able
o end pieces and nose pad a ms. Nickel is also used wi h o he me als o o m alloys
ha a e used o make eyeglass ames, such as s ainless s eel.
Figu e 10 shows Nickel ames eyeglasses.
1
Image sou ce: h ps://enc yp ed- bn0.gs a ic.com/images?q= bn:ANd9GcRaCsys7-D-
sDHAPaBjb0275Ebl3Fi3IsobQQ&s
8
Figu e 10 Nickel eyeglasses.
2
2.2.2.3 Nickel sil e
Also known as alpaca o Ge man sil e , nickel sil e is an alloy o coppe , zinc, sil e ,
and nickel. I is a s ong, igid ma e ial sui able o hinges, end pieces, b idges, and
deco a i e im. This ma e ial is b i le, making i a poo choice o ame on s o hin
pa s. Howe e , when used as an inne co e o plas ic emples, i imp o es he
du abili y o he p oduc and allows o longe las ing adjus men s.
Figu e 11 shows Nickel-Sil e eyeglasses.
Figu e 11 Nickel-Sil e eyeglasses.
3
2.2.2.4 S ainless s eel
S ainless s eel ames a e popula o hei s eng h, e en in hin, s eamlined designs.
This alloy o manganese, nickel, i on, and ch omium is igid and ough, making some
adjus men s di icul . As a esul , hese ames should i well ini ially. S ainless s eel's
2
Image sou ce: h ps://lune es-shop.de/en/Vin age-Glasses/S yle-E a/1900-1940/nickel-spec acles-
black.h ml
3
Image sou ce: h ps://www.op icianonline.ne /cpd-a chi e/4377/
15
2.3.1 Me al eyeglasses manu ac u ing
The making o he componen s p ocess consis s o ou s eps: shaping, g inding,
cu ing, and bending each indi idual me al pa s such as ings, emples, b idges, e c.
The shaping can be done ei he by manual me hods o using oil p ess machines wi h
molds, his p ocess is called s amping and empe a u es anging om 400°C o 700°C
a e needed depending on he me al alloy. The shaped componen s a e immed o
emo e sha p edges and bu s, hen a e ben in o hei inal shape.
Figu e 17 shows a s amping machine used o me allic eyeglasses componen s shaping
Figu e 17 S amping machine o eyeglasses componen s shaping.
13
The inal componen s a e assembled and joined by solde ing, being lase solde ing
mos ly p e e ed due o i s high p ecision and he minimal impac done on he me al,
al hough adi ional solde ing can be used when joining di e en me als. The
empe a u e needed o solde ing depends on he solde ma e ial, solde ing a 180°C-
300°C o so solde s such as Tin (Sn), Lead (Pb), Bismu h (Bi), e c., and up o 600°C
o Sil e (Ag) solde , he las is o en used o componen s unde high mechanical
s esses.[14]
Figu e 18 shows an example o solde ing o eyeglasses componen s
13
Image sou ce: h ps://www.linkedin.com/pulse/how-manu ac u e-me al-eyewea -s ep-sean-yang/
16
Figu e 18 Lase solde ing o eyeglasses componen s.
14
The manu ac u ing p ocesses o me al and plas ic ames a e desc ibed as ollows,
and he in o ma ion (unless o he wise no ed) is aken om he same sou ce.[13]
2.3.1.1 Me allic emples
One manu ac u ing me hod used o hese componen s is o s amp he emples om
he me al shee , in o he cases a me al cylinde is used and is s e ched in o he desi ed
leng h o being molded in o i s inal o m.
2.3.1.2 Eye wi es
These pa s a e made o i anium o alloys such as s ainless s eel o nickel-coppe (Ni-
Cu) alloys. These componen s a e ben in o he desi ed shape by using cu ling
machines.
2.3.1.3 Finishing
In he inal s age o eyewea manu ac u ing, solde ing o spo welding is used o a ach
pa s such as nose pad a ms and b idges. This p ocess is done by hand bu can be
eplaced wi h au oma ed ul asonic and lase solde ing o imp o e adhesion and
du abili y.
14
Image sou ce: h ps://www.zen ech.com/images/welding-lase -sml.jpg
17
One o he inal s ages o p oduc ion is he gal anizing o he me al pa s by imme sing
hem in a se ies o ho ba hs o p o ec he me al pa s om en i onmen al isks and
make hem mo e aes he ically a ac i e and du able.
2.3.2 Plas ic eyeglasses manu ac u ing
The o e all p ocess consis s o h ee main s eps: shaping (which can be done by o
he mo o ming o by injec ion molding), polishing and colo ing. In he he mo o ming
p ocess he ini ial pa is cu om he ma e ial shee and is hea ed o so en he ma e ial
a empe a u es om 150°C o 250°C depending on he polyme used, hen a e shaped
unde p essu e using molds.
In he injec ion molding p ocess, plas ic pelle s a e mel ed in o a liquid s a e o be hen
injec ed unde high p essu e ough a nozzle in o a mold, a empe a u es om 160°C
o 320°C depending on he polyme used.
Figu e 19 shows injec ion molding molds used o manu ac u ing eyeglasses ames.
Figu e 19 Molds used in injec ion molding.
15
The polishing s ep in ol es emo ing manu ac u ing ma ks, connec ion poin s, and
umbling in wood pelle s, also hand polishing is done o mo e p ecise a eas, his s ep
is also a p epa a ion o he colo ing s ep, which can be done by using colo ed plas ic
ma e ials o pain ing.[15]
Figu e 20 shows eyeglasses a e polishing p ocess wi h wood pelle s.
15
Image sou ce: h ps://www.linkedin.com/pulse/how-p oduce-plas ic-eyewea - om-sc a ch-sean-
yang/? ackingId=Qh%2BlEsFeS2aZ%2BN1luIXZCw%3D%3D
18
Figu e 20 Polished eyeglasses wi h wood pelle s.
16
2.3.3 Cellulose ace a e eyeglasses manu ac u ing
Cellulose ace a e (CA) is he mos commonly used ma e ial o he p oduc ion o
polyme ic ames because i is s able, ligh and o e s unlimi ed colo ing possibili ies.
This ma e ial is mixed wi h addi i es (which will be explained la e ) o o m a
composi e ha is la e comp essed by hea ed olle s o o m shee s o blocks o made
in o g anula o ms ha a e hen mel ed and used o make injec ion molded ames.
The CA shee s a e cu in o smalle blocks ha a e hea ea ed o p e en sh inkage,
his hea ea men is called oas ing and is done a 60°C o one week, hese ea ed
shee s a e cu in o he di e en componen s using CNC machines and hen a e bended
o shaped using he same he mo o ming p ocess desc ibed be o e.
Bo h plas ic and CA eyeglasses equi e he inse ion o a me al co e inside he emples
o gi e mo e s abili y and a oid de o ma ion o he polyme ic componen s, his is done
by hea ing he emples a empe a u es o 100°C o 150°C o so en he polyme
making i easie o inse he me al co e, using a s amping machine he me al co e is
placed in he co ec posi ion.[16]
Figu e 21 shows he p ocess o me al co e inse ion in he emples.
16
Image sou ce: h ps://www.linkedin.com/pulse/how-p oduce-plas ic-eyewea - om-sc a ch-sean-
yang/? ackingId=Qh%2BlEsFeS2aZ%2BN1luIXZCw%3D%3D
19
Figu e 21 Me al co e inse ion in CA emples.
17
2.3.3.1 CA F ame on s and emples
The on s o he ames a e milled om small shee s o cellulose ace a e using
pan og aph machines, which mill he emples i s on he inside and hen on he
ou side.
The manu ac u ing p ocesses a e desc ibed as i ollows, and he in o ma ion is aken
om a manu ac u e o eyeglasses in I aly.[17]
• Block p ocess: is a handc a p ocess used o ob ain h ee-dimensional
designs anging om na u al e ec s, h ough he ep oduc ion o ab ics, o
geome ic e ec s o g ea complexi y. The aw ma e ials used in his p ocess
a e cellulose ace a e powde , plas icize s, and sol en s; hese aw ma e ials a e
combined un il a malleable mix u e is ob ained, hen he impu i ies a e
elimina ed by hea y il a ion. The colo in he mix u e is applied h ough a
calende ing p ocess ha homogenizes he colo s and smoo hs he mix u e. The
esul ing shee s a e supe imposed in p esses and mel ed by means o hea and
p essu e. A e he las p essing, he inal shee s a e cu and s aigh ened o he
desi ed hickness, and he sol en is emo ed om hem by e apo a ion.
• Ex usion p ocess: is an indus ial p ocess used o ob ain shee s om
colo ed g anules. This p ocess in ol es he use o a co-ex usion line whe e
g anules o di e en colo s a e mel ed and passed h ough a dye. Once ou side
he dye, he shee is cooled and cu o he app op ia e size.
• Comp ession p ocess: is a p ocess ha uses semi- inished p oduc s coming
om he i s wo p ocesses, which a e e en ually cu in o p ede e mined
17
Image sou ce: h ps://www.linkedin.com/pulse/ace a e-eyewea -bulk-p oduc ion-b eak-down-
sean-yang/? ackingId=Qh%2BlEsFeS2aZ%2BN1luIXZCw%3D%3D
20
shapes, mel ed again in a mold ha allows o ob ain he inal shee wi hou
using sol en s as in block p ocess.
• Lamina ion p ocess: allows o mul iply some desi ed isual e ec s in a
new shee by combining di e en componen s, ob ained om he p e ious
h ee p ocesses, h ough lamina ion. Fo example, by combining di e en colo
ex uded shee s and lamina ing hem.
• Die cu ing: is pe o med a e p ehea ing he ma e ial uni o mly a a
empe a u e a ound 50°C, his is mos ly done by high- equency hea ing
de ices. I he p ocess is done a a oo low empe a u e, chipping on he su ace
can be p oduced.
• Co e inse : is done keeping he empe a u e o he elec odes used o
hea ing he emples o hea he co e, inse ing, and posi ioning i wi hou
causing dis o ions, changes, o de o ma ion o he ma e ial due o excessi e
hea ing.
• The mo o ming o bending: is used o de o m he shee s in o cu es o
ounded endings keeping hei o m s able o e ime, o ensu e his, i is
necessa y o pe o m he bending a a empe a u e ha is su icien o dele e
he elas ic memo y o he polyme . This is done by using a empe a u e 10-
15°C highe han he glass ansi ion empe a u e (Tg) o he polyme ,
commonly used empe a u es a e 90, 100, 110, 120, and 130°C.
The hea ing sys ems ha a e mos equen ly used a e:
• Hea ing by in a ed ays (IR).
• Hea ing by ho pla es ( esis o s).
• High equency (Radio equency RF o Mic owa es MW).
• Liquid ba hs (glyce in).
3. Elec ic hea ing heo e ical backg ound
Elec ic hea ing, also called “elec ohea ” consis s o a ious echnologies ha
ans o m elec ical ene gy in o hea o di e en indus ial applica ions. The elec ic
hea ing p ocesses a e cha ac e ized by he abili y o deli e high empe a u es, high
powe densi ies, all in sho imes and high equency, and wi h high ene gy
e iciency[18].
21
This wo k will in oduce and desc ibe he elec ic hea ing echnologies o induc ion,
adio equency, and mic owa e hea ing.
3.1 Induc ion hea ing
Induc ion hea ing is based on he hea p oduced on elec ically conduc ing ma e ials
unde he in luence o cu en s induced by al e na ing magne ic ields. The
ansmission o he elec omagne ic ene gy is done wi hou di ec con ac om he
induc o o he wo kpiece. The main ad an ages o he p ocess ely on he gene a ion
o hea sou ces inside he wo kpiece o be hea ed in a e y sho ime, he possibili y
o concen a e he hea in speci ic a eas[19], and i s high e iciency o elec ical ene gy
use compa ed o uel hea ing. F om a echnological poin o iew, his p ocess has a
wide accep ance because o i s capabili y o epea abili y, he hea ing cha ac e is ics,
and i s high p oduc ion a es due o high powe densi ies possible wi h his p ocess.
Nowadays he ull heo e ical unde s anding o he physical phenomena in ol ed,
combined wi h nume ical simula ion so wa e, gi es he abili y o design new and
mo e e icien induc o s. The use o new solid-s a e componen s like gene a o s allow
he de elopmen o high powe and e iciency equency con e e s o deli e a whole
equency ange o di e en applica ions.[20]
3.1.1 Ma hema ical equa ions
The induc ion hea ing is based on he mechanism o hea gene a ion in he subs a e
om induced elec ic cu en s. The induc ion o cu en s is a consequence o Fa aday’s
law, which implies ha an al e na ing magne ic ield 𝐵 gene a es an elec ic ield
𝐸[21], as desc ibed in equa ion (EQ1).
𝑟𝑜𝑡 𝐸=−𝜕𝐵
𝜕𝑡
I an elec ically conduc i e ma e ial is exposed o an elec ic ield, elec ic cu en s
a e induced acco ding o Ohm’s law[22], desc ibing he elec ic cu en densi y 𝐽 as
shown in equa ion (EQ2).
𝐽=𝜎𝐸
(EQ1)
(EQ2)
22
The induced elec ic ield c ea es Eddy cu en s wi hin he ma e ial, which has h ee-
dimensional elec ical conduc i i y 𝜎.
The olume ic hea gene a ion a e o powe densi y 𝑃 can be calcula ed wi h Joule’s
law desc ibed in equa ion (EQ3).
𝑃=𝐽𝐸=𝜎𝐸2
Based on he olume ic hea gene a ion a e, he empe a u e dis ibu ion is ob ained
by sol ing Fou ie ’s equa ion o hea conduc ion in solids as desc ibed in equa ion
(EQ4).[23]
𝜌𝐶𝑝𝜕𝑇
𝜕𝑡=−𝑟𝑜𝑡(𝑘 𝑟𝑜𝑡 𝑇)+𝑃
Whe e:
𝜌 Densi y o he ma e ial (Kg/m3)
𝐶𝑝 Speci ic hea capaci y (J/Kg⋅K)
𝑇 Tempe a u e (K)
𝑘 The mal conduc i i y (W/m⋅K)
𝑃 Powe densi y (W/m2)
Induc ion hea ing is in luenced by he skin e ec , which causes he cu en o
concen a e nea he su ace o he conduc o , his can be ep esen ed by he pene a ion
dep h 𝛿 ha de e mines how deeply he cu en pene a es he ma e ial and a ec he
e iciency and he dis ibu ion o he hea ing. Equa ion (EQ5) desc ibes he pene a ion
dep h.
𝛿=√2𝜌
𝜋𝜇0𝜇𝑟𝑓
Whe e:
𝜌 ma e ial esis i i y (Ωm)
(EQ3)
(EQ4)
(EQ5)
23
𝜇0=4𝜋∙10−7 magne ic pe meabili y o acuum (H/m)
𝜇𝑟 ela i e magne ic pe meabili y o ma e ial
𝑓 equency (Hz)
3.2 Dielec ic hea ing
Dielec ic hea ing is based on he he mal e ec ha a high equency al e na ing
elec ical ield p oduces in a dielec ic ma e ial. These dielec ic ma e ials a e
cha ac e ized by bo h low elec ical and he mal conduc i i y. The he mal e ec is
due o he pola iza ion p ocess which consis s in mo ing , o ien ing, and o a ing he
ions (i any) o dipole molecules inside he ma e ials by applying an ex e nal elec ic
ield, c ea ing cu en and hea .
Dielec ic hea ing can be done bo h by adio equency and mic owa es.
Con en ionally he hea ing p ocesses using a equency ange be ween 1 and 100 MHz
a e conside ed as adio equency hea ing, while p ocesses using highe equencies
a e conside ed as mic owa e hea ing.[20]
3.2.1 Radio equency hea ing
In an RF hea e , a high- equency ield is c ea ed be ween he elec odes o a wo king
capaci o , he shape o he elec odes de e mines he shape o he ield. Al hough
a ious elec ode shapes a e possible, od and pla e elec odes a e he mos common.
A lossy dielec ic is placed be ween o o e he elec odes o induce hea ing. The
elec ic ield s eng h is de e mined by equency, applied ol age, and elec ode
spacing. The p ac ical elec ode spacing is limi ed by he applied ol age, as inc easing
spacing equi es highe ol ages o main ain ield s eng h. The maximum elec ode
spacing, and p oduc hickness a e limi ed o p e en a cing be ween he
elec odes.[24]
3.2.1.1 Ma hema ical equa ions
The speci ic elec os a ic ene gy pe uni olume 𝑤𝐸 o a dielec ic ma e ial in which
an elec ic ield 𝐸 and an elec ic lux densi y 𝐷
a e p esen , can be exp essed by he
equa ion (EQ6).
24
𝜕𝐷
𝜕𝑡
𝑤𝐸=𝐸∙𝐷
2
Wi h:
𝐷
=𝜀0𝐸+𝑃=(1+ 𝑃
𝜀0𝐸)𝜀0𝐸=(1+𝜒𝑒)𝜀0𝐸=𝜀0𝜀𝐸
Whe e:
𝑃=𝜒𝑒𝜀0𝐸 dielec ic pola iza ion ec o
𝜀0=8.86×10−12 dielec ic cons an o acuum (F/m)
𝜒𝑒 dimensionless quan i y known as elec ic suscep ibili y o
ma e ial.
The i s Maxwell equa ion in a domain whe e 𝐸 and 𝐷
a e p esen can be no ed by
he equa ion (EQ7).
𝑟𝑜𝑡 𝐻
=𝜎𝐸+𝜕𝐷
𝜕𝑡
Whe e:
𝐻
magne ic ield in ensi y (A/m)
𝜎 elec ical conduc i i y (S/m)
𝐻
= 𝜎𝐸 conduc ion cu en densi y (A/m2)
Displacemen cu en densi y (A/m2)
Unde he in luence o an al e na ing elec ic ield, he pola iza ion is no
ins an aneous, he ec o 𝑃 lags o he applied elec ic ield. This is why he coe icien
𝜒𝑒 is a complex numbe and he e o e he ec o 𝐷
lags o he elec ic ield 𝐸 a an
angle 𝛿𝑝 which desc ibes he ac i e powe deli e ed in he dielec ic ma e ial du ing
he pola iza ion p ocess.
(EQ6)
(EQ7)
31
3.3.4 Volume Pola iza ion
I is a pola iza ion phenomenon obse ed in mul i-componen ma e ials whe e one
componen consis s o la ge olumes o conduc i e ma e ial. Examples include we
ma e ials con aining wa e , o subs ances such as ood and wood, which a e
cha ac e ized by a cellula s uc u e. Inside hese cells is a conduc i e luid, while he
cell bounda ies a e made o dielec ic ma e ial. When an elec ic ield is applied, ions
and ee elec ons mo e wi hin he conduc i e pa s, causing he conduc i e inclusions
o unc ion as la ge-pola ized molecules wi h dipole momen um. Due o he non-
uni o m s uc u e o he ma e ial, cha ge mo emen is con ined o he mac o-
inclusions, which beha e like bound cha ges.[20]
The ma e ial pola iza ion beha io depends on he equency, empe a u e, and mois .
Depending on he equency he dipoles will mo e o no , in s eady s a e (ω=0), he
dipoles do no mo e , also when equency is maximum (ω=ꚙ), he dipoles will no
ha e ime o mo e, so in bo h cases he losses a e equal o ze o ( gδ=0). This beha io
is ep esen ed in Figu e 26.
Figu e 26 Ci cula diag am o complex dielec ic pe mi i i y as a unc ion o equency. [20]
The e a e o he ac o s ha a ec he dielec ic p ope ies o ma e ials; o example,
o wa e , he dissipa ion ac o is highly dependen on empe a u e and chemical s a e
( ee, ionized, c ys allized, con ined).
The loss ac o o any ma e ial depends on condi ions such as empe a u e, in e nal
humidi y, equency, chemical and physical s a e o he ma e ial, and he di ec ion o
he applied elec ic ield.
32
Unde s anding he heo e ical backg ound o dielec ic hea ing is c i ical o he
applica ion o hese echnologies o speci ic ma e ials, pa icula ly polyme s, which
play a key ole in he eyewea indus y. The dielec ic p ope ies o hese polyme s a e
undamen al o op imize he hea ing p ocesses desc ibed be o e.
4. Polyme ic dielec ic ma e ials
Bo h low and high pe mi i i y dielec ics play c i ical oles in he elec onics indus y.
Low dielec ic cons an ma e ials se e p ima ily as insula o s, o en e e ed o as
passi a ion ma e ials. They a e used o isola e signal-ca ying conduc o s, acili a e
as signal p opaga ion, se e as in e laye dielec ics o mi iga e esis ance-
capaci ance (RC) ime delays, minimize c oss alk, and educe powe dissipa ion in
high-densi y, high-speed in eg a ion scena ios.[31]
Ac i e componen s aim o high ε alues, ideal o capaci o s, elec omagne ic wa e
de ices, ec i ie s, semiconduc o de ices, piezoelec ic ansduce s, dielec ic
ampli ie s, and memo y elemen s. While inhe en ly non-pola , ma e ials can be
pola ized wi h ace impu i ies, enabling signi ican cha ge s o age e en unde
minimal elec ic ields. One example is poly inylidene luo ide wi h impu i ies as
chlo o i luo oe hylene demons a es his e ec .[32]
4.1 Dielec ic p ope ies o polyme s
The dielec ic esponse o polyme s is mainly associa ed wi h dipola , a omic, and
elec onic pola iza ion. Dipola pola iza ion depends on he elaxa ion o elec ic
dipoles esponding o he al e na ing elec ic ield in a equency ange up o 108 Hz
and lead ma e ials o exhibi high dielec ic cons an s. In he case o a omic
pola iza ion, he phenomenon is caused by nucleus displacemen , which occu s a
in a ed equency (1013 Hz). Elec onic pola iza ion is due o elec ons mo emen ,
which can be p oduced in he ul a iole equency domain (1015 Hz), is also ela ed
o he bandgap o he dielec ics.[33]
Figu e 27 shows a g aphical demons a ion o he pola iza ion mechanisms men ioned
be o e.
33
Figu e 27 Pola iza ion mechanisms o polyme ic-dielec ic ma e ials as a unc ion o equency. [34]
Polyme s exhibi lowe dipole momen and dipola co ela ion compa ed wi h
e oelec ic ce amics; hese ac o s joined wi h highe ba ie s o he dipole’s o a ion
p esen in polyme s a e he majo causes o lowe dielec ic cons an ound in
dielec ic polyme s.[35]
Ce ain s uc u es and elemen s, such as a oma ic ings, sul u , iodine, and b omine,
exhibi high pola izabili y, leading o an inc ease in dielec ic cons an . F ee olume,
de ined as unoccupied space wi hin a polyme , also in luences dielec ic cons an ; he
p esence o po es dec eases i because ai occupies his space wi h a ela i e
pe mi i i y o abou one.
Tempe a u e a ec s dielec ic p ope ies by a ec ing in e molecula o ces, inc easing
he mal agi a ion, and allowing pola g oups o o ien mo e eely, hus a ec ing he
dielec ic cons an . A lowe empe a u es, chain segmen al mo ion dec eases,
educing he dielec ic cons an , while a highe empe a u es, s ong he mal mo ion
dis up s dipole o ien a ion, again dec easing he dielec ic cons an .[6]
4.2 Cellulose ace a e (CA) as dielec ic polyme .
Polyme dielec ics a e gene ally amo phous o semi-c ys alline s uc u es, and hose
subjec ed o high empe a u es mus ha e a high glass ansi ion empe a u e (Tg) and
a high mel ing empe a u e (Tm).[36]
Cellulose ace a e is a semi-c ys alline biopolyme and has a epo ed Tg o 83.40°C, i
is insoluble in wa e , i s chemical p ope ies a e unique as i con ains he ca boxyl
34
g oups (C=O) in i s s uc u e. In addi ion, i has good ilm o ming p ope ies due o
i s in e molecula hyd ogen bonds, he e o e cellulose ace a e ilms ha e high
mechanical s eng h.[37]
Analysis o dielec ic pa ame e s o cellulose ace a e such as ε’ and ε’’ shows ha a
low equencies he e is an inc ease due o he o ma ion o a space cha ge egion a
he elec ode in e ace, known as non-Debye ype beha io . This beha io is a ibu ed
o ion di usion[38]. A low equencies, ε’ and ε’’ a e high due o in e acial
pola iza ion and ee cha ge mo ion[39]. A high equencies, howe e , mobile ions
ha e di icul y o ien ing due o apid elec ic ield e e sals, leading o sa u a ion, o
dec eased dielec ic cons an [40].
5. Ene gy e iciency in Eu ope’s indus ies
The Eu opean Union (EU) has se ambi ious ene gy e iciency goals, looking o a
leas 32.5% imp o emen by 2030 compa ed o he p e ious goal o 20% by 2020.
These a ge s d i e inno a ion and in es men in indus y, p omo ing he de elopmen
o ene gy-e icien echnologies and p ac ices. Adop ing imp o ed ene gy e iciency
p ac ices, can esul in educ ions in ene gy bills, g eenhouse gas emissions, heal h
issues, and in imp o emen in quali y o li e, all o his helping he EU o achie e he
commi men s o he Pa is Ag eemen on clima e change.[41]
The Ene gy E iciency Di ec i e equi es EU coun ies o educe hei annual ene gy
consump ion by an a e age o 4.4% by 2030. This di ec i e aims o educe ene gy
consump ion, and Eu ope’s dependance on ene gy impo s, by s imula ing in es men
in new echnologies, and p o iding be e in o ma ion on ene gy bills so ha
consume s know how o con ibu e o a mo e sus ainable, inno a i e, and p ospe ous
EU.[42]
The indus ies in Eu ope accoun o 25% o he o al inal ene gy consump ion, om
which 73% is needed o hea ing and cooling, he o he 27% is used o mechanical
applica ion d i en by elec ici y. The indus y is di e se, and some p ocesses equi e
di e en empe a u es anging om 160°C and up o 2000°C, o example, he
p oduc ion o plas ics equi es empe a u es om 180°C o 290°C, while d ying
echnologies equi e a empe a u e ange om 160°C o 180°C.
35
In 2020 he use o enewable ene gy o hea ing and cooling was 21.5% and is expec ed
o be 27-31% in 2030 and 47-54% in 2050. [43]
Some app oaches sugges sa ings po en ials in he indus y by applying mo e han 230
ene gy sa ing measu es, om which 100 a e ela ed o hea p ocess. These measu es
include in eg a ed con ol sys ems, exhaus gas and low empe a u e hea eco e y, he
use o highe e iciency bu ne s (o hea sou ces), and ma e ials subs i u ion. The
applica ion o hese measu es would be ansla ed in o a 20% educ ion o ene gy
consump ion and 4-5% ene gy sa ings by 2030 and 8-10% by 2050. [44]
The imp o emen a eas o indus y wi h highe ene gy e iciency ely on inno a i e
and e icien echnologies, p ocess in ensi ica ion, and he in eg a ion o enewable
sou ces. The p ocesses imp o emen can be achie ed h ough he use o e icien
equipmen such as e icien boile s, s eam sys ems, and he use o s a e-o - he-a
kilns.[43]
S a e-o - he-a kilns a e ad anced indus ial hea ing sys ems designed o maximize
ene gy e iciency, p ecision, and pe o mance in a ious manu ac u ing p ocesses.[45]
These sys ems include mode n and e icien hea sou ces, ad anced insula ion
ma e ials o minimize hea loss, hea eco e y sys ems o cap u e and euse was e hea
and au oma ed con ol sys ems, ha can include solid-s a e powe elec onics such as
gene a o s o con ol he powe deli e y p ecisely and mo e e icien ly.
As indus ies in Eu ope y o become mo e ene gy e icien , he eme gence o Indus y
5.0 p o ides an oppo uni y o in eg a e hese e o s wi h b oade echnological
ad ancemen s. Indus y 5.0 no only aims o enhance ene gy e iciency, bu also o
e olu ionize he way indus ies ope a e by inco po a ing human-cen ic, sus ainable,
and echnologically ad ance p ac ices.
6. Indus y 5.0 in Eu ope’s indus ies
Acco ding o he Eu opean Commission[46], Indus y 5.0 is de ined by echnologies
ha include human-cen ic solu ions and human-machine-in e ac ion, bio-inspi ed
echnologies and sma ma e ials, eal- ime-based digi al wins and simula ion, cybe
sa e da a ansmission, s o age, and analysis echnologies, A i icial In elligence (AI)
and echnologies o ene gy e iciency and us wo hy au onomy.
36
Indus y 5.0 o e s a ans o ma i e app oach o Eu opean indus y ha no only ocus
on e iciency and p oduc i i y, bu also on he de elopmen o mode n, esou ce-
e icien , and sus ainable indus ies. This means he c ea ion o new echnologies ha
p omo e ci cula p oduc ion models, espec ing he limi s o he plane while
inc easing p ospe i y. The sus ainabili y app oach o Indus y 5.0 aims o educe
ene gy consump ion and minimize was e. Resea ch and inno a ion a e cen al o his
ision, p omo ing indus y esilience and be e equipping hem o u u e challenges.
Indus y 5.0 also p omo es he use o sma senso s and equipmen , connec ed de ices,
and ad anced da a analy ics, enabling eal- ime moni o ing and con ol o ene gy
consump ion, minimizing was e, and imp o ing ene gy e iciency. The educ ion in
esou ce consump ion con ibu es o en i onmen al sus ainabili y.[47]
The eyewea indus y was unde going signi ican ans o ma ion d i en by Indus y
4.0 which was de ined by he in eg a ion o ad anced inno a i e echnologies like AI,
addi i e manu ac u ing, and obo ics in o manu ac u ing p ocesses. These
echnologies ha e allowed g ea e cus omiza ion and enhancemen o p oduc design,
and mo e op imized supply chains. Companies like Ke ing and Luxo ica ha e
implemen ed au oma ed sys ems o make ope a ions mo e e icien . Wi h hese
echnologies he indus y has imp o ed bo h p oduc quali y and p ocesses
inno a ion.[48]
Howe e , as he indus y ad ances echnologically, he e is he need o sus ainable
business models o mi iga e he en i onmen al impac o he inc eased ene gy and
esou ce consump ion. While Indus y 4.0 ocuses on business op imiza ion and
economic g ow h, i misses key elemen s o he ue sys emic ans o ma ion. Such as
egene a i e indus ial p ac ices, social inclusion, and manda o y en i onmen al
sa egua ds.[46]
Tha is why Indus y 5.0 appea s like a solu ion o achie e clima e neu ali y by 2050,
p omo ing he EU o shi owa ds g een and socially inclusi e indus ial s a egies,
in eg a ing sus ainable and ci cula economic models, p io i izing he wellness o he
wo ke s, and d i ing deca boniza ion ac oss he indus ies. Eyewea indus y is also
encou aged o in eg a e ci cula economy p inciples o educe was e, enhance
sus ainabili y, and mee cus ome expec a ions, all including long- e m p o i abili y.
37
In he nex chap e , his hesis explo es how he I alian eyewea indus y can apply he
elec ic hea ing echnologies p e iously discussed, along wi h o he bes p ac ices
iden i ied in he li e a u e, o align wi h p inciples o Indus y 5.0. By in eg a ing hese
ad anced echnologies and p ac ices, he indus y can achie e mo e sus ainable and
e icien manu ac u ing p ocesses, suppo ing a mo e esilien and inno a i e sec o .
7. Elec ic hea ing, and o he good p ac ices o be applied in he
I alian eyewea indus y owa ds Indus y 5.0 and sus ainabili y.
7.1 Elec ic hea ing o eyewea indus y
As seen be o e, indus ies like he I alian eyewea indus y need he adop ion and
applica ion o echnologies ha allow he educ ion o ene gy consump ion, and o
make he p ocesses mo e sus ainable. One o he ways o do i is he applica ion o
elec ic hea ing me hods such as induc ion, adio equency and mic owa es hea ing
desc ibed be o e.
These me hods a e well known o hei highe e iciency in deli e ing and dis ibu ing
hea in o he wo kpieces in sho ime. The combina ion o hese me hods wi h
au oma ed machines and solid-s a e gene a o s makes hem an ad an ageous
echnology in ene gy consump ion educ ion, cos sa ings, and quali y assu ance o
he p oduc s in he manu ac u ing p ocesses.
Induc ion hea ing can be used in he welding and hea ing p ocesses o
he moplas ics[22][23], which a e he p ima y polyme s used in eyewea
manu ac u ing. The moplas ic con aining pola g oups can be welded using bo h RF
and MW hea ing, he dielec ic loss in he polyme dissipa es ene gy, gene a ing hea
in e nally, and wi h he applica ion o p essu e he welding is comple ed in ypically a
ew seconds[49]. The welding p ocess is gene ally pe o med a 27.12 MHz, applying
RF h ough shaped elec odes. O he equencies like 13.56 MHz can be used o
elemen s wi h la ge a ea o welding, and 70 MHz is used i welding nylon.[20]
RF hea ing is used also o d y and hea a di e si y o ma e ials in an e icien way, and
by using elec onic ma ching ne wo ks i is possible o inc ease he ene gy e iciency
o hea ing o mo e han 90%[50]. Also, RF hea ing can be used o hea - ea men s and
38
su ace hea ing o me als[51], his can be applied as a hea sou ce o hea ing be o e
s amping and shaping he componen s o me allic eyeglasses.
O he esea ch has shown ha MW hea ing can be used o di e en applica ions
depending on he equi ed p ocessing empe a u e, anging om low empe a u es
below 500°C o hea ing polyme s, o mode a e empe a u es om 500°C o 1000°C
o p ocessing ce amics and low mel ing poin me allic ma e ials, o high p ocessing
empe a u es abo e 1000°C o hea ing high densi y ce amics, high mel ing poin
me als, and me allic-ma ix composi es, all wi h ene gy e iciencies as high as
86%.[52]
7.2 Bes A ailable Techniques o di e en sec o s ela ed o eyewea indus y
This chap e desc ibes s a egies o enhance ene gy e iciency in indus ial sec o s
ela ed o he manu ac u ing p ocesses o eyeglasses, which a e he p oduc ion o
me allic and polyme ic ma e ials ha a e he mos ly used g oup o ma e ials in he
eyewea indus y.
The Eu opean Commission h ough he Eu opean Bu eau o Resea ch on Indus ial
T ans o ma ion and Emissions (EU-BRITE) has de eloped he Re e ence Documen s
on Bes A ailable Techniques (BREFs) o speci ic ag o-indus ial ac i i ies ega ding
he bes echnologies and measu es o be applied o di e en indus ies in o de o
enhance sus ainabili y, ene gy e iciency, and educe emissions and ene gy
consump ion in he Eu opean indus ial sec o s.
The Bes A ailable Techniques (BAT) o ene gy managemen o me allic ma e ials
p oduc ion ocus on enhancing ene gy e iciency h ough s a egies such as he
implemen a ion o Ene gy E iciency Managemen Sys ems (ENEMS) like ISO
50001, he use o egene a i e o ecupe a i e bu ne s, he applica ion o me hods o
hea eco e y om was e p ocesses, he use o high e iciency elec ic mo o s, and
au oma ed con ol sys ems o op imize ene gy consump ion.[53]
The goal o hese s a egies is o imp o e ene gy pe o mance ac oss a ious indus ial
applica ions, especially in high- empe a u e p ocesses, by cap u ing and eusing was e
hea and op imizing ene gy consump ion.
The BAT in he p oduc ion o polyme s ocus on he imp o emen o ene gy e iciency,
he educ ion o emissions, and he op imiza ion o esou ces consump ion ac oss he
39
manu ac u ing p ocesses. The s a egies include he implemen a ion o En i onmen al
Managemen Sys ems (EMS), he use o ad anced-design equipmen o minimize ai
pollu an s, he use o sys ems ha eco e hea , sol en apo s, and o he emissions
o euse.
BAT also p omo es he educ ion o ene gy and wa e consump ion h ough
cogene a ion o hea and powe plan s, wa e eci cula ion sys ems and ad anced
ea men me hods o was e and emissions. The adop ion o sus ainable p ac ices such
as he use o ecycled ma e ials, he educ ion o haza dous was e, and he applica ion
o echnologies o minimize ene gy and wa e consump ion a e pa o he ocus o
hese echniques.[54]
O he ele an BAT a e he ones o imp o e ene gy e iciency in indus ial acili ies,
hei goal is o balance en i onmen al p o ec ion and economic iabili y, and o educe
ene gy consump ion, o enhance en i onmen al managemen , and o minimize
pollu ion. The s a egies s a wi h he iden i ica ion o he issues ela ed o ene gy
e iciency, he e alua ion o e ec i e solu ions, and he de e mina ion o he op imal
e iciency le els, conside ing cos s, policy d i e s, and en i onmen al impac . O he
s a egies a e he implemen a ion o ENEMS and ene gy audi s.
The applica ion o measu es such as he op imiza ion o combus ion and s eam
sys ems, wi h he use o hea eco e y echnologies like hea exchange s and
cogene a ion, and he imp o emen o elec ical sys ems wi h high e iciency
ans o me s a e key o enhance ene gy e iciency and o sus ain ene gy
pe o mance.[55]
7.3 O he good p ac ices ound in li e a u e
In he li e a u e esea ch wo ks ha e conduc ed s udies, analysis, and diagnosis o
issues ela ed o ene gy e iciency in p ocesses such as glass p oduc ion, polyme
injec ion molding and o he indus ial plan s, which will be desc ibed below wi h some
sugges ions o sol e hese issues.
The esea ch has been applied on examples in he eyewea indus y, and mo e
speci ically he p oduc ion o eyeglass ames, compa ing he con en ional
manu ac u ing sys ems, wi h dis ibu ed manu ac u ing sys ems (DMS) and 3D
40
p in ing echnology. The s udy shows ha imp o ing he e iciency o 3D p in ing and
using cleane ene gy sou ces can educe he en i onmen al impac , while ma e ial
selec ion, such as he use o polylac ic acid (PLA), can also educe he oxici y- ela ed
impac , as o he polyme s p oduce oxic gases. While DMS o e s po en ial bene i s,
he inc eased consump ion o 3D p in ed p oduc s due o hei ease and low cos o
p oduc ion could e e se he en i onmen al bene i s.[56]
All hese p oduc ion p ocesses ha e high ene gy consump ion, mos ly because o he
ene gy pe o mance o hei equipmen and i s dis ibu ion, o ins ance, esea ch has
shown ha glass indus y is highly ene gy-in ensi e, wi h an app oxima e
consump ion o ene gy o 700 million GJ pe yea . The eplacemen o ine icien
equipmen wi h equipmen o be e pe o mance is a good s a egy o educe ha
ene gy consump ion. The p oposed measu es consis in he ins alla ion o elec ic
usion u naces, elec ic boos ing o ens, ecupe a i e u naces, and bu ne s o use he
hea o he lue gases o p ehea he s eam o he glass sc aps en e ing he p oduc ion
p ocess. Also, he use o he pa en ed “E-Powe Sys em”, which is a passi e il e ha
adjus s he induc ance o ma ch he powe abso p ion equi ed by he sys em, using
elec ici y ans o me s.[57]
O he esea ch p oposes he applica ion o Addi i e Digi al Molding (ADM), which is
an Indus y 5.0-d i en app oach ha in eg a es digi al e e se enginee ing, addi i e
manu ac u ing, and plas ic injec ion molding o mode nize he p oduc de elopmen .
This echnology gi es a amewo k o ac ions ha ocus on enhancing ene gy
e iciency and sus ainabili y in manu ac u ing p ocesses. By u ilizing Indus y 5.0
echnologies such as he In e ne o Things (IoT), Big Da a Analy ics (BDA), and
Digi al Twins o op imize he manu ac u ing p ocesses, educe was e, and imp o e
supply chain anspa ency. These echnologies allow eal- ime decision-making, on-
demand p oduc ion, and esou ce op imiza ion, all con ibu ing o sus ainabili y.[58]
7.4 Sus ainable Eyewea
I is wo h men ioning ha I aly is he coun y in he EU ha has in es ed he mos in
in enewable ene gies, eaching a 37% o he o al in es men s done in Eu ope in
enewable ene gies p oduc ion[59]. And so a , he impo ance o he I alian Eyewea
Indus y has been desc ibed and no ed in his hesis, some p oposals o echnologies
47
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