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Minimizing waste (off-cuts) using cutting stock model: the case of one dimensional cutting stock problem in wood working industry

Abstract

Purpose: The main objective of this study is to develop a model for solving the one dimensional cutting stock problem in the wood working industry, and develop a computer program for its implementation. Design/methodology/approach: This study adopts the pattern oriented approach in the formulation of the cutting stock model. A pattern generation algorithm was developed and coded using Visual basic.NET language. The cutting stock model developed is a Linear Programming (LP) Model constrained by numerous feasible patterns. A LP solver was integrated with the pattern generation algorithm program to develop a one - dimensional cutting stock model application named GB Cutting Stock Program. Findings: Applying the model to a real life optimization problem significantly reduces material waste (off-cuts) and minimizes the total stock used. The result yielded about 30.7% cost savings for company-I when the total stock materials used is compared with the former cutting plan. Also, to evaluate the efficiency of the application, Case I problem was solved using two top commercial 1D-cutting stock software. The results show that the GB program performs better when related results were compared. Research limitations/implications: This study round up the linear programming solution for the number of pattern to cut. Practical implications: From Managerial perspective, implementing optimized cutting plans increases productivity by eliminating calculating errors and drastically reducing operator mistakes. Also, financial benefits that can annually amount to millions in cost savings can be achieved through significant material waste reduction. Originality/value: This paper developed a linear programming one dimensional cutting stock model based on a pattern generation algorithm to minimize waste in the wood working industry. To implement the model, the algorithm was coded using VisualBasic.net and linear programming solver called lpsolvedll (dynamic link library) was integrated to develop a one dimensional cutting stock Program.

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Minimizing waste (off-cuts) using cutting stock model: the case of one dimensional cutting stock problem in wood working industry

Author: Ogunranti, Gbemileke A.,Oluleye, Ayodeji E.
Publisher: OmniaScience
Year: 2016
DOI: 10.3926/jiem.1653
Source: https://upcommons.upc.edu/bitstream/2117/91389/1/1653-8954-1-PB.pdf
Jou nal o Indus ial Enginee ing and Managemen
JIEM, 2016 – 9(3): 834-859 – Online ISSN: 2013-0953 – P in ISSN: 2013-8423
h p://dx.doi.o g/10.3926/jiem.1653
Minimizing Was e (O -cu s) Using Cu ing S ock Model:
The Case o One Dimensional Cu ing S ock P oblem in
Wood Wo king Indus y
Gbemileke A. Ogun an i1 , Ayodeji E. Oluleye2
1D exel Uni e si y (Uni ed S a es)
2Uni e si y o Ibadan (Nige ia)
gao32@d exel.edu, [email protected]
Recei ed: Augus 2015
Accep ed: Augus 2016
Abs ac :
Pu pose:
The main objec i e o his s udy is o de elop a model o sol ing he one dimensional
cu ing s ock p oblem in he wood wo king indus y, and de elop a compu e p og am o i s
implemen a ion.
Design/me hodology/app oach:
This s udy adop s he pa e n o ien ed app oach in he
o mula ion o he cu ing s ock model. A pa e n gene a ion algo i hm was de eloped and coded
using Visual basic.NET language. The cu ing s ock model de eloped is a Linea P og amming
(LP) Model cons ained by nume ous easible pa e ns. A LP sol e was in eg a ed wi h he
pa e n gene a ion algo i hm p og am o de elop a one - dimensional cu ing s ock model
applica ion named GB Cu ing S ock P og am.
Findings:
Applying he model o a eal li e op imiza ion p oblem signi ican ly educes ma e ial
was e (o -cu s) and minimizes he o al s ock used. The esul yielded abou 30.7% cos sa ings
o company-I when he o al s ock ma e ials used is compa ed wi h he o me cu ing plan.
Also, o e alua e he e iciency o he applica ion, Case I p oblem was sol ed using wo op
comme cial 1D-cu ing s ock so wa e. The esul s show ha he GB p og am pe o ms be e
when ela ed esul s we e compa ed.
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Resea ch limi a ions/implica ions:
This s udy ound up he linea p og amming solu ion o
he numbe o pa e n o cu .
P ac ical implica ions:
F om Manage ial pe spec i e, implemen ing op imized cu ing plans
inc eases p oduc i i y by elimina ing calcula ing e o s and d as ically educing ope a o mis akes.
Also, inancial bene i s ha can annually amoun o millions in cos sa ings can be achie ed
h ough signi ican ma e ial was e educ ion.
O iginali y/ alue:
This pape de eloped a linea p og amming one dimensional cu ing s ock
model based on a pa e n gene a ion algo i hm o minimize was e in he wood wo king indus y.
To implemen he model, he algo i hm was coded using VisualBasic.ne and linea p og amming
sol e called lpsol edll (dynamic link lib a y) was in eg a ed o de elop a one dimensional cu ing
s ock P og am.
Keywo ds:
1D-cu ing s ock p oblem, cu ing s ock model, pa e n gene a ion algo i hm, linea
p og amming
1. In oduc ion
A cu ing s ock p oblem (CSP) basically consis s o cu ing la ge pieces a ailable in s ock o p oduce
smalle pieces (called i ems) in o de o mee a gi en demand. The cu ing is planned o minimize was e
o he s ock ma e ial (o he objec i es may a ise). These objec i es may be o minimize im loss, he
numbe o cu ing lines o p oduc ion cos , maximize p o i and so on. In a cu ing plan, he equi ed se
o pieces om he a ailable s ock leng hs mus be ob ained. The objec i e is o minimize he numbe o
used s ock leng hs o , equi alen ly, im loss (was e) (Mu a , U a & Ahme , 2011). This ype o p oblem
occu s in se e al indus ies such as pape , aluminium, s eel, glass, and u ni u e indus y among o he s.
Kall a h, Rebennack, Kall a h and Kusche (2014) sol ed cu ing s ock p oblem in he pulp and pape
indus y wi h he objec i e o minimizing he numbe o olls and he pa e ns, he eby p e en ing
o e p oduc ion.
The one-dimensional cu ing s ock p oblem (1D-CSP) can be s a ed as ollows: Gi en a se o i ems I,
each i em i ∈{1, ..., m} o leng h li and demand o bi pieces, o be cu ou o a i ually in ini e supply o
s ock leng h L (whe e 0 < li ≤ L,  i  I), in o de o minimize he numbe o s ock objec s used
(Ga a a, Salassa, Vanc oonenbu g, Be ghe & Wau e s, 2014). The p oblem conside ed in his pape is o
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ind a cu ing plan ha would minimize he was e ma e ial when a se o o de s di e en in leng h and
quan i y is o be cu om a pack o s ocks wi h cons an leng h (Yang, Sung & Weng, 2006).
The pu pose o his pape is o de elop a ma hema ical model o sol ing he one dimensional
cu ing s ock p oblem in he wood wo king indus y and de elop a use iendly compu e p og am
o i s implemen a ion. Many wood wo king companies a e seeking ways o minimizing p oduc ion
was e (and maximize p o i ) bu aced wi h lack o echnical know-how and compe ency o so do.
Thus, he e is need o a e y easy o ope a e and in e p e cu ing s ock p og am o imp o ing
ope a ional e iciency. Based on he p oblem encoun e ed, a me hodology o in eg a ing he cu ing
pa e ns gene a ion algo i hm wi h LP sol e was de eloped. In o de o achie e he was e
minimiza ion objec i e, he cu ing s ock model was coded in o a compu e applica ion using Visual
Basic.NET language.
This pape is o ganized as ollows: sec ion 2 e iews he ela ed wo k on he cu ing s ock p oblem. In
sec ion 3, he me hodology and solu ion app oach a e p esen ed. Sec ion 4 p o ides he p oblems sol ed
o demons a e p ac ical applica ion o he model. Sec ion 5 p esen s esul s ob ained by applying he one
dimensional cu ing s ock model. Finally, he las sec ion concludes he s udy and op imal cu ing using
he 1D-cu ing s ock p og am was p oposed.
2. Li e a u e Re iew
2.1. Cu ing and Packing P oblems
Cu ing and packing p oblems a e combina o ial op imiza ion p oblems. As wi h many o he
p oblems o his kind, hey a e easy o s a e, and di icul o sol e. Ma sumo o, Ume ani and
Nagamochi (2011) also e e ed o hese p oblems as NP ha d. The s anda d p oblem is de ined as
ollows: gi en a se o small and la ge objec s, how he small objec s should be ob ained om he
la ge ones in o de o op imize a gi en c i e ion. The ypical es ic ions o which a cu ing o packing
plan is submi ed a e he impossibili y o he small objec s o o e lap, and he limi ed capaci y o
leng h o he la ge objec s.
The e a e wo main app oaches o sol e his p oblem: exac and heu is ic me hods. Exac algo i hms a e
mainly based on linea /dynamic p og amming and b anch-and-bound echniques. Vande beck (1999)
in oduced a b anch-and-p ice algo i hm based on column gene a ion app oach o sol ing he cu ing
s ock p oblem. The au ho ocus on how s anda d b anch- and-bound enhancemen ea u es such as
ea ly b anching, a iable ixing, and he use o cu ing planes can be inco po a ed in he b anch-and-p ice
algo i hm. Then, how o selec app op ia e b anching p io i ies, and implemen a ounding heu is ic.
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Mo e ecen ly, Ka ak, Ripa i, Schei haue and Ku z (2014) used algo i hmic app oach based on
exhaus i e enume a ion and in ege linea p og amming o sol e one-dimensional cu ing s ock p oblem
(1CSP) wi h espec o he in ege ound-up p ope y (IRUP).
Mo eo e , heu is ic me hods ha e g ea e lexibili y in aking in o accoun p oblem speci ic cons ain s
and o e a ade-o be ween he quali y o a solu ion and i s compu a ional e o . They a e equi ed o
p o ide good, bu no necessa ily op imal solu ions. Some o he new heu is ics me hods ound in he
cu en li e a u e a e: (Dikili, Takinacı & Pek, 2008; Ma sumo o e al., 2011; A aujo, Poldi & Smi h, 2014;
Che i, A enales & Yanasse, 2013; Ga a a e al., 2014; Cui, Zhong & Yao, 2015). A aujo e al. (2014)
p esen s a heu is ics me hod based on gene ic algo i hm o sol e one-dimensional cu ing s ock p oblem
by conside ing wo con lic ing objec i e unc ions: minimiza ion o bo h he numbe o objec s and he
numbe o di e en cu ing pa e ns used.
P e iously, Dyckho (1990) de ined a o mal ypology o cu ing and packing p oblems by
sys ema ically in eg a ing a ious kinds o p oblems and no ions. This ypology was imp o ed by
Wäesche , HauBne and Schumann (2007) wi h he de ini ion o new ca ego iza ion c i e ia. Table 1
shows he ypology ound in he li e a u e.
Dyckho ’s C&P ypology Waesche ’s imp o ed C&P ypology
Dimensionali y
1
2
3
N
One-dimensional
Two-dimensional
Th ee-dimensional
N-dimensional
1
2
3
N
One-dimensional
Two-dimensional
Th ee-dimensional
N-dimensional
Kind o assignmen
B
V
All la ge objec s and a selec ion o small objec s
A selec ion o la ge objec s and all small objec s
OM
IM
Ou pu alue maximiza ion
Inpu alue minimiza ion
Asso men o la ge objec s
O
I
D
One la ge objec
Many iden ical la ge objec s
Di e en la ge objec s
O
SO
One La ge objec
OA all Fixed dimensions
OO one a iable dimension
OM mo e a iable dimensions
Se e al La ge objec s
SI Iden ical La ge objec s
SW weakly he e ogeneous asso men
SS s ongly he e ogeneous asso men
Asso men o small objec s
F
M
R
C
Few small objec s o di e en igu es
Many small objec s o many di e en igu es
Many small objec s o ela i ely ew di e en igu es
Many iden ical small objec s
IS
W
S
Iden ical small i ems
Weakly he e ogeneous asso men
S ongly he e ogeneous asso men
Table 1. Dyckho ’s (1990) and Waesche ’s (2007) ypologies o C&P p oblems
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Dyckho classi ies he solu ion o one dimensional cu ing s ock p oblem in o wo: i em o ien ed and
pa e n-o ien ed app oaches. I em o ien ed app oach is cha ac e ized by indi idual ea men o e e y i em
o be cu . In he pa e n o ien ed app oach, a i s , o de leng hs a e combined in o cu ing pa e ns, o
which - in a succeeding s ep - he cu ing equencies a e de e mined in o de o sa is y he demands. The
cons ain s in he pa e n-o ien ed app oach a e based on he algo i hm o Gilmo e and Gomo y (1961,
1963). Howe e , a pa e n-o ien ed app oach is possible only when he s ock is o he same leng h o o
se e al s anda d leng hs. An i em-o ien ed app oach is used when all s ock leng hs a e di e en and
equencies canno be de e mined.
2.2. One Dimensional Cu ing and Packing Models
In he li e a u e, esea che s ha e used di e en exac and heu is ics solu ion app oaches o suppo
cu ing s ock decision making in he indus y (Kall a h e al., 2014). Mos ecen ly, Delo me, Io i and
Ma ello (2016) p o ides a comp ehensi e e iew o he main ma hema ical models and algo i hms
de eloped o exac ly sol ing he one-dimensional bin packing and cu ing s ock p oblems. The p oblems
conside ed in hei e iew a e classi ied as 1-dimensional SBSBPP (Single Bin Size Bin Packing P oblem)
and 1-dimensional SSSCSP (Single S ock Size Cu ing S ock P oblem). Also, a su ey o cu ing s ock
p oblems wi h usable le o e s can be ound in Che i, A enales, Yanasse, Poldi and Vianna (2014) as
hese p oblems does no i he classi ica ion based on he ypology p oposed by Wäsche e al. (2007).
Mos o he app oaches o sol ing he s anda d cu ing and packing p oblems in a single dimension
based on linea p og amming models ha ha e been p oposed can be di ided in o ou ca ego ies:
a) The Assignmen Fo mula ions
b) The Pa e n-O ien ed Fo mula ions
c) The One-Cu Fo mula ions
d) The Flow Models
2.2.1. The Assignmen Fo mula ions
The i s in ege linea p og amming o mula ion was p oposed by Kan o o ich (1960), based on
assignmen o a iables as ollows.
(1)
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Subjec o:
(2)
(3)
(4)
(5)
Whe e: he abo e model has bina y and gene al in ege a iables; wi h yj been he choice o oll j, Xij is
he numbe o i ems o size wi assigned o oll j and Wi is he capaci y o he bin i. Equa ion 3 is he
knapsack cons ain s, one o each oll, while equa ion 2 is he demand (bi) cons ain s wo king as he
linking cons ain s. Whe e n is a known uppe bound on he numbe o olls needed, yj = 1, i oll k is
used, and 0 o he wise, and a iable Xij is he numbe o imes i em i is cu in oll j. A lowe bound o he
op imum can be ob ained om he op imum o i s LP elaxa ion, which esul s om subs i u ing he wo
las cons ain s o 0 ≤ yj ≤ 1 and Xij ≥ 0.
Ma ello and To h (1990) showed ha he lowe bound p o ided by he LP elaxa ion can be e y weak.
This model’s main d awback is ha i p oduces poo lowe bound wi h la ge was e. Good quali y lowe
bounds a e o i al impo ance when using LP based app oaches o sol e in ege p oblems (Ca alho,
2002).
2.2.2. The Pa e n-O ien ed Fo mula ions
The pa e n o ien ed model o Gilmo e and Gomo y (1961) ollowed he assignmen o mula ion o
Kan o o ich. Gilmo e and Gomo y (1961) o mula ed he cu ing s ock p oblem as an in ege
p og amming p oblem. The cu ing s ock p oblem can be modelled as:
(6)
Subjec o:
(7)
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(8)
(9)
(10)
Whe e,
L is he leng h o he objec s in s ock;
li is he leng h o he i ems, i = 1, 2, …, m;
bi ep esen s he demand o i em i, i = 1, 2, …, m;
Aj = (a1j, …, aij, …, amj)T be a cu ing pa e n, i = 1, 2, …, n, whe e aij is he numbe o i ems i in he
pa e n;
Xj be he equency ha he pa e n j is cu .
The di icul y in using his model is he la ge numbe o pa e ns o be enume a ed in p ac ical p oblems.
Since, he possible pa e ns numbe s inc eases exponen ially as he numbe o di e en i ems and he
demands inc eases.
2.2.3. The One-Cu Fo mula ions
In he one-cu models, independen ly p oposed by Rao (1976) and Dyckho (1981), he p inciple is o
de e mine how o apply a single cu (a one-cu ) on an o iginal o esidual piece o ma e ial. A one-cu
di ides he aw ma e ial in wo pieces: an o de ed i em and a esidual objec as shown in he igu e below.
Figu e 1. One-Cu
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The la e pa can be im loss, a po ion o be cu u he , o ano he o de ed wid h. The model
p oposed by Dyckho conside s he case in which di e en s ock leng hs a e a ailable. In he sequel, D
ep esen s he se o i em wid hs o cu om he s ock olls whose leng hs belong o S = {W1, ..., WK}.
The se o esidual objec s whose leng h is su icien ly la ge o cu an i em is deno ed by R. The decision
a iables yp,q indica e he numbe o imes a piece wi h leng h p is o be cu so as o p oduce an i em o
wid h q, and a esidual objec o wid h p−q. The zk a iables indica e he numbe o s ock olls wi h
leng hs Wk ha a e used. The Dyckho ’s model is as ollows:
(11)
Subjec o:
(12)
(13)
(14)
(15)
(16)
Whe e,
S is he se o he (sizes o he) o iginal objec s, p ∈ {W1, W2, …, WK}  N
R be he se o he (sizes o he) esidual pieces ob ained a e cu ing an i em om an objec o a
esidual piece i sel
D be he se o he (sizes o he) i ems q ∈{w1, w2, …, wm} ⊂N. We assume wi hou loss o gene ali y
ha S ∩ D = Φ
yp,q be he numbe o pieces o size p ha a e di ided in o a piece o size q, and a esidual piece o
size p – q
zk deno es he numbe o objec s o size Wk used
Nq s ands o he demand o i ems o size q
Bp is he numbe o objec s o size p in s ock, p = 1, 2, …, K.
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The majo disad an age o his model is he inc easing numbe o a iables as he numbe o i ems
inc eases. The possible sizes o esidual pieces can be la ge and hey need o be enume a ed o sol e he
p oblem. This model also canno be ex ended, a leas in a s aigh o wa d manne o bi-dimensional o
mul idimensional cu ing s ock p oblems.
2.2.4. The Flow Models
The a c low o mula ions a e based on low a iables. Le G = (V, A) be an acyclic di ec ed g aph wi h
e ices V = {0, 1, 2,…, W} whe e W is he size o he objec in s ock and A = {(i, j ): 0 ≤ i < j ≤ W} is
he se o a cs. The e exis s a di ec ed a c (i, j ) in his g aph G i he e is an i em d o size wd and j – i = wd.
Ca alho (1999) modelled he one-dimensional cu ing s ock p oblem as an a c low model. In his
model, a uni o low om node 0 o node W co esponds o a cu ing pa e n since i de ines a pa h
om node 0 o node W whe e he addi ion o he sizes o he i ems in co espondence o he a cs in his
pa h is smalle han he size o he objec . The ma hema ical o mula ion o he a c low model is gi en
below:
(17)
Subjec o:
(18)
(19)
(20)
(21)
(22)
Whe e,
Z is he low in a eedback a c, om e ex W o e ex 0
Xij is he low in a c (i, j )
bd is he demand o i em d, d = 1, 2, …, m.
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4. The op imal cu ing pa e n is now selec ed by sol ing he LP model (wi h ou applica ion) which
minimizes he o al was e.
5. Clicking on sol e bu on on he GB cu ing s ock p og am, he esul s displays on wo di e en
abs (Tex solu ion and Visual solu ion espec i ely).
6. The o al s ock ma e ials used (Summa ion o all Xj) is gi en as:
(30)
To al cos o s ock shee used is es ima ed using equa ion 31 s a ed below.
(31)
7. F om he ex solu ion o he LP model, he o al was e (o -cu s) can be e alua ed om he alue
o he objec i e unc ion o he model
8. A isual solu ion is p esen ed showing i ems and o -cu s (was e) on each op imal cu ing pa e n
wi h di e en colou on he second esul ab.
4. Model Applica ion
To demons a e he applicabili y o he model, wo p ac ical cases a e p esen ed in his pape . Case I
ela es o he cu ing p oblem encoun e ed a a Fu ni u e and Joine y Company while Case II he cu ing
p oblem a a gene al wood wo ks company in Nige ia. Bo h companies a e p i a ely owned.
4.1. Case I
Twel e (12) lush doo s a e o be p oduced om 55mm wid h wood o s anda d leng h 12 (3660mm).
Fi e 55mm wid h wood can be cu om a s anda d plank, since 10mm wid h is cu o o s aigh en he
s anda d plank edges and he blade wid h akes abou 4mm away a each cu .
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Pa Numbe Pa Leng h(mm) Numbe Requi ed o a Doo To al Numbe Requi ed
1 2000 2 24
2 710 4 48
3 540 2 24
4 620 2 24
5 625 5 60
Table 2. Requi emen s o he O de
F om he cu en p ac ice in he company I, hi een (13) planks we e used o ul il his ask. Since, a
plank o dina ily yields i e 55mm wid h wood, he e o e a o al o six y- i e (65) 55mm wid h wood is
equi ed. The cos pe uni o plank is one housand wo hund ed nai a (#1200). Fi e 55mm wid h wood
can be ob ained om a plank; his implies ha a uni o 55mm wid h wood echnically cos s wo hund ed
and o y nai a (#240).
4.2. Case II
Two p oduc s we e selec ed ou o he da a collec ed om Company II. The p oduc s a e as ollows:
4.2.1. P oduc I: Con e ence Chai s
Tables 3 and 4 summa ise he da a equi ed o p oduce 30 pieces o con e ence chai s as equi ed.
Wid h Numbe Used Planks Used
9cm 32 11
7cm 10 3
5cm 12 2
To al Planks Used 16
Table 3. Numbe o s ock leng h used by cu en p ac ice o p oduce he chai s
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Pa s Componen Leng h (cm) Numbe pe Chai Numbe Used
9cm wid h
1 A ms 64 2 60
2 F on legs 58 2 60
3 C osses (F on & Back) 54 2 60
7cm Wid h
1 Sides 58 2 60
5cm Wid h
1 Back legs 68 2 60
Table 4. De ails o Pa s lis o he con e ence chai
4.2.2. P oduc II: Panel Doo s
The s anda d size o a panel doo is 206cm X 84cm. Cu en p ac ice e ealed ha en (10) panel doo s
a e p oduced om hi y (30) planks based on he p esen cu ing echnique. A panel doo consis s o
h ee di e en ypes o he s ock ma e ial om which each equi ed leng h is ob ained. These a e o
wid hs 28cm, 15cm and 10cm. The de ails o each equi ed componen is gi en on Table 5 below.
Pa s Componen Leng h (cm) Numbe pe Doo Numbe Used
28cm wid h
1 Small panel 32 2 20
2 La ge panel 64 4 40
15cm Wid h
1 Up igh 206 2 20
2 C osses 76 3 30
10cm Wid h
1 C osses 76 3 30
2 V. small c oss 33 1 10
Table 5. De ails pa s lis o he Panel Doo s
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5. Resul s and Discussion
The So wa e p esen s esul s in wo o ms: The ex solu ion and he isual solu ion. The ex solu ion
gi es he desc ip ion o pa e ns o be cu , o al numbe o s ock o be used and i s cos ; while isual
solu ion shows he diag am o how he op imal pa e n is o be cu .
F om Table 6, he model ecommends he o al s ock (55mm wid h wood) o be used is 42. Since, i e
pieces 55mm wid h wood a e ob ained om a plank; o y- wo (42) 55mm wid h wood will gi e 8.4planks
(app oxima ely 9 s anda d size planks should be used). Nine planks yield o y- i e 55mm wid h wood,
he eby allowing wo 55mm wid h wood o be kep as ese e in case o mis akes while cu ing. Figu e 4
shows he op imal cu ing pa e ns o be used. The esul s ob ained show ha 9 planks should be used
ins ead o he cu en 13, which esul in a sa ing o 30.7%.
5.1. Tex Solu ion
The ex solu ion ob ained om he model can be summa ized below:
Pa e n No. (
j
) LP Solu ion (
Xj
) Numbe Cu Leng hs (mm) To al Was e(
WjXj
)
mm
2000 710 625 620 540
2 21.6 22 22 44 - - - 5280
8 2.4 2 2 - - - 8 120
9 0.96 1 - 5 - - - 110
35 15 15 - - 60 15 15 0
50 1.8 2 - - - 10 2 40
To al 41.76 42 24 49 60 25 25 5550
Table 6. Solu ion o Case I p oblem (Flush Doo )
Pa e n No. (
j
) LP Solu ion (
Xj
) Numbe Cu Leng h (cm) To al Was e (
WjXj
)
cm
64 58 54
3 15 15 60 - 30 30
21 15 15 - 60 30 390
To al 30 30 60 60 60 420
Table 7. Numbe o 9cm wid h o be used o p oduce P oduc I (Case II)
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Pa e n No. (
j
) LP Solu ion (
Xj
) Numbe Cu Wid h (cm) To al Was e (
WjXj
)
cm
9 7 5
1 3.17 4 12 - - 12
2 10 10 20 10 10 -
7 0.5 1 1 - 4 1
To al 13.67 15 33 10 14 13
Table 8. To al numbe o planks o be used o Case II P oduc I (Con e ence Chai s)
Pa e n No. (
j
) LP Solu ion (
Xj
) Numbe Cu Leng h (cm) To al Was e (
WjXj
)
cm
64 32
2 8 8 40 8 112
7 1.09 2 - 22 28
To al 9.09 10 40 30 420
Table 9. Numbe o 28cm wid h o be used o p oduce P oduc II (Case II)
Pa e n No. (
j
) LP Solu ion (
Xj
) Numbe Cu Leng h (cm) To al Was e (
WjXj
)
cm
206 76
1 5 5 5 - 800
2 15 15 15 30 120
To al 20 20 20 30 920
Table 10. Numbe o 15cm wid h o be used o p oduce P oduc II (Case II)
Pa e n No. (
j
) LP Solu ion (
Xj
) Numbe Cu Leng h (cm) To al Was e (
WjXj
)
cm
76 33
2 6.92 7 28 7 203
3 0.77 1 3 4 6
To al 7.69 8 31 11 209
Table 11. Numbe o 10cm wid h o be used o p oduce P oduc II (Case II)
Pa e n No. (
j
) LP Solu ion (
Xj
) Numbe Cu Leng h (cm) To al Was e (
WjXj
)
cm
28 15 10
1 10 10 10 - - 20
2 10 10 - 20 - 0
4 2.67 3 - - 9 0
To al 22.67 23 10 20 9 420
Table 12. Solu ion o Case II P oduc II (Panel Doo )
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5.2. Visual Solu ion
Figu e 4 p esen an illus a ion o he isual solu ion ab o he applica ion. This shows he numbe o
each i em p oduced pe pa e n and he o – cu s (was e). Simila ly, GB Cu ing S ock P og am p o ides
isual solu ion o all o he cu ing plan solu ions.
In addi ion, implemen ing he cu ing pa e ns esul shown in Tables 7 and 8 espec i ely o he
con e ence chai s e eals ha i een (15) planks mus be consumed as agains he 16 planks used. This
gi es a sa ing o 6.25% o he o ganisa ion. In a la ge scale ope a ion, he sa ings could be subs an ial in
mone a y e ms.
Simila ly, implemen ing he cu ing pa e ns esul shown Tables 9-12 espec i ely o p oduce he panel
doo s shows ha wen y- h ee (23) planks a e equi ed ins ead o hi y (30) planks used. This leads o a
ne sa ing o 23.3% when compa ed o he numbe o planks used by he o me cu ing plan.
Figu e 4. Op imal Cu ing Plans o he lush doo p oblem.
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5.3. Compa ison S udy
To e alua e he e iciency o GB cu ing s ock p og am, wo comme cial so wa es ha ha e execu able
ial e sion a ailable on he in e ne was used o sol e he p oblem p esen ed in case I. The summa y
esul s ob ained a e as shown on Table 13.
So wa e Ma e ials Used Pa e n Used To al Was e (mm) Ma e ials
To al Cos (#)
GB Cu ing P og am 42 5 5,550 10,080.00
A 42 6 6,300 10,080.00
B 44 6 13,620 10,560.00
Table 13. Numbe o ma e ials, pa e n used, o al was e and cos by each p og am
The websi e o he comme cial so wa es a e lis ed on appendix I as A and B. Comme cial so wa e
package A p oduce he same op imal esul as ou cu ing s ock p og am in e ms o ma e ial used and
u ilized 6 pa e ns as shown in Figu e 5 o implemen he same esul . While comme cial so wa e
package B used he same numbe o pa e ns wi h so wa e A bu mo e ma e ials han bo h GB cu ing
p og am and A. The e o e, GB cu ing s ock is be e because i uses less numbe o pa e ns and educes
ope a ion ime han A and B. See appendix II o op imal cu ing pa e ns solu ion using so wa e B.
Figu e 5. Op imal Cu ing Plans gene a ed using package A
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Also, conduc ing p ice su ey on comme cial so wa e packages e eals ha i would cos wi hin
$100 - $400 (20,000 - 78,000 local cu ency) o pu chase a license. This is cos ly o local woodwo k
indus y in Nige ia which canno ansac in in e na ional cu ency. Thus, GB cu ing s ock p o ides easy
o use p og am wi h no p io compu e knowledge o local woodwo king indus y.
6. Conclusion
The cu ing s ock model and a pa e n gene a ion algo i hm we e de eloped. The algo i hm was coded
using VisualBasic.ne and a ee linea p og amming sol e called lpsol edll (dynamic link lib a y) was
in eg a ed o de elop a one dimensional cu ing s ock p og am named GB cu ing s ock p og am. The
cu ing s ock model signi ican ly educes ma e ial was e, elimina es calcula ing e o s, d as ically educes
ope a o mis akes and minimizes he o al s ock used, he eby imp o es p oduc i i y. Also, he esul s
ob ained we e compa ed agains he bes solu ion gene a ed by wo comme cial so wa es o he same
p oblem. I can be concluded ha GB cu ing s ock p og am yielded a e y good esul a easonable
compu a ional ime and pe o ms be e han he comme cial so wa e in e ms o ope a ional e iciency
ha is i equi es less ime o implemen esul s. Finally, due o i s a o dabili y; implemen ing ou esul
yielded a signi ican cos sa ings o abou 30.7% o company-I when he o al s ock ma e ials used is
compa ed wi h he o me cu ing plan.
Acknowledgemen s
We would like o hank he B i ish Council o suppo ing his wo k unde he AKTP (A ican
Knowledge T ans e Pa ne ship) ini ia i e wi h a G an . We also hank he anonymous e e ees o hei
help ul commen s and all hose who made sugges ions as o making he applica ion simple o use in
p ac ice.
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