PERFORMANCE EVALUATION OF CORRUGATED
PACKAGING - A KEY TO SUCCESS FOR
PAPERMAKERS AND CORRUGATORS
Sanjay Tyagi, B. P. Thapliyal, R. D. Godiyal, Prachi Kaushik and
Manoj Kumar
CENTRAL PULP AND PAPER RESEARCH INSTITUTE
SAHARANPUR- 247001
• Pulp & Paper industry is one of the largest
industrial sector in world producing 404
million MT of paper & paper board annually.
• Asia contributes highest production with 182
Mmt followed by Europe (106 Mmt) and
North America (85Mmt)
Paper and PaperBoard Production (%)
50
45
40
35
30
25
20
15
10
5
0
Asia
Europe
North
America
Latin
America
Oceania
Africa
(Source: Compendium of Census Survey of Indian Paper Industry, CPPRI (2015))
Region-wise Production of Paper and Paperboard
Global Production Trends
• Global Pulp & Paper industry shows positive
growth despite a decline in production in
graphic paper in North America and Europe.
• Positive growth of tissue and packaging grades
has offset the retreat of graphic paper.
• According to FAO, paper and board packaging
product will continue to represent industry’s
largest segment with contribution of more than
50% of worldwide paper production.
Paper and paper board
Production (%)
40%
35%
30%
25%
20%
15%
10%
5%
0%
37%
26%
14%
8%
Corrugated Printing
Paper
Material and Writing Board for
Paper
Packaging
Tissue
Paper
8%
7%
Otherpaper Newsprint
(Source: Compendium of Census Survey of Indian Paper Industry, CPPRI (2015) )
Grade-wise Global Production of Paper
Global Paper Consumption
• Highest consumption of paper is registered
for Asia, Europe & North America
• China accounts for 25% of world demand
against 26% of global production of paper
and board.
• Europe consumes 24% of paper against the
contribution of 27% of global paper
production.
Consumption of Paper (%)
50%
45%
40%
35%
30%
25%
20%
15%
10%
5%
0%
46%
24%
20%
7%
Asia
Europe
North
America
Latin
America
2%
1%
Africa
Oceania
(Source: Compendium of Census Survey of Indian Paper Industry, CPPRI, 2015)
Region- wise Global Consumption of Paper
221
200
215
159
156
150
126
100
75
50
50
47
23
13.2
Af
r ic
a
In
dia
Ch
Ko
ina
re
a,
Ta
iw
Re
an
st
of
As
ia
O
ce
an
La
ia
tin
Am
er
ica
O
EU
th
er
Eu
ro
pe
Ja
pa
n
Am
er
ic
a
0
No
rth
Per Capita Consumption
250
(Source: Compendium of Census Survey of Indian Paper Industry, CPPRI (2015))
Paper Consumption kg/capita
8
Fact sheet of Indian Paper industry
Number of Mills
813
Total installed capacity, MMT
22.15
Operating Installed capacity, MMT
19.27
Production of Paper, board & newsprint, Mtpa
14.99
Capacity utilization, %
80
Per capita consumption (kg)
13.2
Contribution to exchequer, Rs. crores
4500
Employment Direct, million people
0.5
Indirect Employment, million people
1.5
Indian share in world’s production
3.7
(Source: Compendium of Census Survey of Indian Paper Industry, CPPRI (2015))
Indian Paper Industry segment based on
Products
Variety
Raw Material
Writing
Printing Grade
Wood Based
2.67
Agro Based
0.54
Recycled Fibre
Based
2.00
Wood Based
0.85
Agro Based
1.07
Recycled Fibre
Based
6.37
Wood Based
0.02
Agro Based
Nil
Packaging
Grade
Newsprint
Grade
Recycled Fibre
Based
Total Production
Production
(Mtpa)
Total
production
Mtpa
% Contribution
5.21
35*
8.29
55*
`1.49
10*
14.99
100
1.47
(Source: Compendium of Census Survey of Indian Paper Industry, CPPRI (20150))
Projected requirement of different
varieties of Paper
• It is estimated that production of paper will
reach 21.94 million tons in 2025 against
present production of 14.99 million tons.
• Industry requires an addition of 6.95 million
ton production capacity over a period of 10
years i.e an addition of 0.69 million ton
/annum.
Projected Growth of different varieties of
Paper
Paper Grade
Growth rate in %
Writing/Printing Paper
• Coated Paper
10
• High grade maplitho
08
• Copier Paper
15
• Cream wove
05
Industrial Paper and Board
• Container and Corrugated board
10
• Carton Board
08
Newsprint
06
Specialty Paper
05
(Source: Compendium of Census Survey of Indian Paper Industry, CPPRI (2015))
Use of Paper and Paperboard for Packaging
• Bags, wrapping and infusible tissues e.g. Tea and coffee bags, sachets,
pouches, over wrap, sugar and flour bags, carrier bags
• Multiwall paper sacks
• Folding car tins and rigid boxes
• Corrugated and solid fiberboards boxes
• Paper based tubes, tubes and composite containers
• Fiber drums
• Liquid packaging
• Labels
• Sealing tapes
• Cap liners (sealing wads) and diaphragms (membranes)
•
•
•
•
•
Contain the product.
Protect goods from mechanical damage
Preserve products from deterioration.
Information to customer / consumer.
Provide visual impact through graphical and
structural design.
Technical Requirement of Paper and Paper Board for
Packaging
• All papers and paper board properties depend on the
ingredients used e.g. type and amount of fiber and other
materials, together with the manufacturing process.
• These related to the visual appearance and technical
performance of packaging incorporating such materials.
• Appearance that relates to color, visual impression and the
needs of any processes such as printing which have a major
impact on the appearance of the packaging.
• Performance that relates to strength, product/consumer
protection and the efficiency of all the production operations
involved in making and using the packaging.
Corrugated fiber board packaging
• Corrugated fiber board packaging in terms of
weight, is the commonest type of paper and
paper board based packaging.
• It function is mainly the protection of
products during distribution.
• Popularity of corrugated board as packaging
material is primarily because of its high
strength- to- weight ratio
Relative price verses relative strength of
various packaging materials
Source: Alf dr Ruvo, “Development trends in packaging”, PRIMA supplement in Paper
Europe, volume3, number 4, July 1991)
Structure of Corrugated Board
• Corrugated board has a sandwich material
structure.
• It comprises a central paper (called the
corrugating medium or simply the medium)
which has been formed using heat, moisture
and pressure in a corrugated i.e. fluted,
shape on a corrugators and one or two flat
papers (called liners) have been glued to the
tips of the corrugations
Structure of Corrugated board
a
Single Face
b
Single wall
c
Double wall
d
Triple wall
Corrugating Flutes Profiles
Flutes
D
K
A
C
B
E
F
G
O
Average
Number of
flutes / m
75
95
110
129
154
295
310
350
360
Pitch (mm)
Take up factor
14.96
1.70
8.60
7.95
6.50
3.50
2.40
1.80
1.25
1.48
1.50
1.53
1.42
1.31
1.24
1.22
1.21
1.14
‘Technical Corrugating Roll Data’,BHS Corrugated brochure by
Edmund Bradatsch and Lothar Jobst – July 2000)
(Sourse:
Properties of corrugated paper board and
their test procedure
•
•
•
•
•
•
•
•
•
•
Weight per unit area (grammage)
Thickness (caliper)
Bursting Strength
Rigidly or bending stiffness
Edge Crush test
Flat crush test and hardness
Concora Medium Test
Puncture Test
Adhesion Test and Score cracking
Box Compression Test
Weight per unit area (grammage) and
thickness (caliper)
• Grammage = L1 + (a x F) + L2
where L1 and L2 are the liners, F is the medium and ‘a’ is takeup factor.
• The take- up factor defines the length of the
medium (fluting) material used in a
corrugated fiberboard structure compared
with the length of the facings.
Thickness or Caliper
• The thickness (caliper) is measured under 20 kPa pressure
Average value of thickness for different flutes in given below
Flute
Caliper or Thickness (mm)
D
8.0
K
6.5
A
4.8
C
4.2
B
2.8
E
1.7
F
1.2
G
1.0
O
0.7
Why measuring the corrugated caliper is
important?
• Caliper is an indirect measure of the compression
stacking of corrugated boxes.
• Low caliper is usually the result of poorly formed
flutes or crushed flutes and often results in poor
corrugated box performance.
• Whenever the caliper of given grade of board is less
than the target value, it failed to achieve the
maximum strength potential.
How to maximize caliper?
• From the flutes to the maximum potential of
the corrugated rolls
• Do not to crush the flutes after we have
formed them.
Strength Properties
• The strength and durability of corrugated
board lies in the strength of the components
it made up of.
• A 20 x 20 x 20 – 200 lbs (976g/m2) test Cflute corrugated box can withstand almost
408 kg of weight before failing, yet it weighs
only 1.02 kg.
• Reason lies in the fact that fluted medium
separating two liners act as columns.
Bursting Strength
• It is indication of the character of the materials
used in the manufacturer of the box.
• Depending on nature and grammage of the
liners, large range of quantities from 800 to 8000
kPa is available.
• This test gives no direct information regarding
the ultimate performance of the design or
construction of a finished container.
• Burst strength test is of critical importance as a
control test in the paper board mill.
• Triple wall corrugated board can not be tested
suitably by the burst test method.
• Testing of double wall is of questionable accuracy
since it is rarely possible to get sufficiently
simultaneous burst of the multiple facing.
• For single wall corrugated board, the following
equation is applied
Burst Strength = L1 + L2 + 100
Where L1 & L2 are the burst strength of the liners in
kPa.
Rigidly or Flexural bending stiffness
• Relates the force required to deflect a flat
specimen of corrugated board through a given
angle.
• Capacity of structural members to resist
bending.
• Greater the flexural stiffness, greater is the load
required to produce a given deflection.
• Combined board flexural stiffness in each
direction is summing the product of elastic
modulus of each component.
• Combined board Stiffness
S = EtH2/2
where E = Elastic modulus of liners
t = liner thickness
H = combined board caliper
• Combined board stiffness is sensitive to
caliper of combined board, thus it is
necessary to avoid crushing the board during
conversion.
• C Flute has higher bending stiffness than B
Flute
• Corrugated fiber board based on kraft liner
has a higher bending stiffness than test liner
of same grammage
• Bending stiffness increases with increasingly
liner grammage.
Edge Crush test
• Evaluate the compression strength of the corrugated board
as per ISO 3037. Expressed as the breaking force divided by
the sample width (kN/m).
• Relates directly to the top to bottom compressive strength
of corrugated shipping container.
• Method is used for comparing the edge wise compression
strength of different lots of similar board or for comparing
different materials combinations
Maltenfort Equation
• ECT = k(σ CL1 + σ CL2 + α σ CF )
where σ C = compression strength of liners & flutting medium
paper measured by any method SCT, RCT, CLT, CCT
α = take – up factor
k = constant depending on manufacturing variables of
corrugated board
• 15 – 20% of ECT potential of corrugated
board is lost during fluting process due to
high bending and tension stresses induced in
medium paper during fluting.
• Application of steaming operation though
relieved stresses but it reduces elastic
modulus and compressive strength of sheet
by 5 – 15%.
Edge Crush Test pieces
25 mm
100 mm
paraffin
Flat crush test and hardness
• Evaluate and classify the performance of the
fluting in accordance with the type and basis
weight.
• Measure of the resistance of the flutes in
corrugated board to crushing force applied
perpendicular to the surface of the board
under prescribed conditions (ISO 3035)
• Measures the flute rigidity of the corrugated
board.
• High FCT value indicates a good combination
of the flute formation and at least adequate
medium strength.
• A low flat crush value indicates a number of
faulty conditions.
Flat Crush Test
• FCT test is satisfactory for single faced or
single wall corrugated board but should not
be used for double wall or triple wall board.
• This test gives the intrinsic performance of
the flutes predicted by the Concora Medium
Test (CMT) and by basis weight
• The FCT thus records how appropriate the
fluting medium is for processing on the
corrugators
Hardness
• In order to evaluate properly the
performance of soft board, the hardness of
corrugated board is other important
criterion.
• Hardness is the resistance of the board in
early stage of FCT. It relates to the real
strength of the flutes whereas FCT is late
yield point.
Effect of crushing force on flutes
Force
3500
6
3000
4
2500
5
2000
2
3
1500
1000
leaning flutes
500
0
Compression
1
1
2
3 mm
PUNCTURE TEST
• This test illustrates the energy required to
penetrate the corrugated board.
• Conducted as per ISO 3036 standard. Values
are reported in mJ/m.
• This test gives better performance of
corrugated box as compared to Burst test.
Concora Medium Test
•It is a test of compression of the paper after fluting
in fluting apparatus.
•The CMT value is the maximal force the sample can with
stand before it breaks.
Concora Medium Tests
Tape
Pin Adhesion Test (PAT) and
Score cracking
• The Pin adhesion Test (PAT) is used to evaluate the
bonding between the fluting and liner.
• Adhesion resistance is the maximum force required
to separate the linerboard from the fluting with the
help of special sample holder.
• In single face bonding, the adhesive is
distributed on each side of the flute tip.
• In double backers, the adhesive deposit is
placed on the top of the tip.
• Score cracking effect occurs during
converting operation due to stress-strain
occurring in folding & erecting.
How Box Collapse?
• In conventional vertical flute boards, with
progressively increasing load, side & end panels
become unstable & deflect laterally.
• Having become unstable, central region of each panel
suffers appreciably reduction to accept further
increase in load & box bow outward or inward.
• Edges carry greatest intensity of load & rupture of box
at edges triggers failure of entire box.
• Box Compression test (BCT) is the best representation
to practical stacking strength of corrugated board
boxes.
Box Compression Test
• Stackability of corrugated boxes is best determined
by box compression test (BCT) expressed as KN or
kg.
• BCT is the top to bottom compression strength.
• To conduct this test, the container is placed
between the platens of the test machine and
compressed at a rate of 0.5 in/min. The maximum
load and deflection at failure is recorded.
Box Compression Tester
• Box Compression strength = K x ECTa x FSb x Dc
where D is the dimension of box (perimeter),
FS is the flexural stiffness of the board,
ECT is the edge crush test of board and
K, a, b and c are empirical constants.
• ECT of combined box is a dominant factor in top
load box compression strength.
• A % increase in ECT strength, contribute three
times greater increase in BCT as compared to %
increase in flexural stiffness & 1 – ½ times the same
increase in box perimeter
Factors negatively affecting the top
load Compression strength
Humidity
Effect of relative humidity o compressive strength property
of corrugated boards
• Corrugated box looses half or more of its
short term top load compression strength
when relative humidity increased by 50%.
• BCT falls from 350±50 kg (at 23°C/50% RH) to
130±15 kg (at 20°C /90%RH)
• With increasing moisture content, ultimate
paper strength properties reduced due to
reduction in inter fiber bondings.
Age
• With number of days the box is under
compression, compression strength of box
began to loose at an alarming rate.
• This is due to creep within the cellulose fiber
structure of the paper and the corrugated
material itself.
• As a thumb rule, 50% of its stacking strength
will be lost over six months period.
Misalignment
• Vibration disturb system stability.
• BCT value of box from 300 kg falls by 40% (170 kg)
due to vibration.
Column stack verse Interlock
Compression strength of corrugated box as a function
of stackability
Pallet Overhang
Effect of pallet overhanging on compression strength of
corrugated boxes
Rough Handling
• Mishandling including dented vertical edges
on the container can result in as much as 50%
decrease in the box compression strength
when compared to the virgin container.
Conclusion
• Growing market has placed demands upon the
corrugated case producers for better quality both in
terms of strength and visual apperance.
• For achieving above points it become very essential
to evaluate the performance parameters of
corrugated boxes at every stage of production and
converting.
• This should be done by adopting the correct
procedure of testing of liner, medium and
corrugated box with state of art equipments by
following standard test methods.