102
783

 

THE RELATION BETWEEN
EDGEWISE COMPRESSION STRENGTH AND THE
DEGREE OF THE ANGLE PERPENDICUIAR TO
THE COMPRESSWE FORCE OF CORRUGATED
FIBREBOARD

Thesis for the Degree of M. S.
MICHIGAN STATE UNIVERSITY
JAMES FRANCIS 3086
1972

 

ABSTRACT

THE RELATION BETWEEN EDGEWISE COMPRESSION
STRENGTH AND THE DEGREE OF THE ANGLE
PERPENDICULAR TO THE COMPRESSIVE
FORCE OF CORRUGATED FIBREBOARD

BY

James Francis Borg

This study was undertaken to determine what, if any,
differences exist in edgewise compression strength of
corrugated fibreboard, when the angle of the score, perpen-
dicular to the compressive force, is varied from unscored,
180 degrees, through the angles of 135, 90, 45, and 30
degrees. From this data a ratio or ratios of length to
width (L/W) for maximum compressive or stacking strength
was determined. Samples of B-flute, ZOO-lb. test corrugated
fibreboard, twelve inches square were compressed, with the
height remaining constant and the distance from the score
varying one inch from the edge, perpendicular to the direc-
tion of the compressive load, to a maximum of six inches
from that edge. This was repeated for all angles tested.

A ratio of the length to width (L/W) of between 1.20 and
1.40 and a 90 degree angle was found to be the combination

that gave the greatest compressive strength.

THE RELATION BETWEEN EDGEWISE COMPRESSION
STRENGTH AND THE DEGREE OF THE ANGLE
PERPENDICULAR TO THE COMPRESSIVE

FORCE OF CORRUGATED FIBREBOARD

BY

James Francis Borg

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

School of Packaging

1972

v. ‘- . r
«as:

.
‘.r
wi.

pun?

i Fx
5' ‘ '

ACKNOWLEDGMENTS

The author wishes to acknowledge and thank Dr. Wayne
Clifford and Mr. Sergei Guins for their invaluable help in
preparing this thesis.

A special acknowledgment is also made to Mr. Fred
Holcomb and Mr. Harry Vick, Jr., of the Quaker Oats Company

for their encouragement and advice.

ii

TABLE OF CONTENTS

Page
ACKNOWLEDGWNTS O O O O O O O O O O O 0 O 0 ii
LIST OF TABLES . . . . . . . . . . . . . . iv

LIST OF FIGURES . . . . . . . . . . . . . . V

Chapter
I. INTRODUCTION . . . . . . . . . . . . 1
II. EXPERIMENTAL PROCEDURE . . . . . . . . . 6
Design of Study . . . . . . . . . . 6
Preparation . . . . . . . . . . . 7
Apparatus . . . . . . . . . . . . 7
Test Method . . . . . . . . . . . 7
Compression Test . . . . . . . . . 8
III. ANALYSIS OF DATA . . . . . . . . . . . 14
Analysis of Test Results . . . . . . . 14
IV. CONCLUSIONS . . . . . . . . . . . . 24

BIBLIOGRAPHY O O O O O O O O O O O O O O O 25

APPENDIX 0 O O O O 0 O O O O O O O O O O 27

iii

Table

1.

LIST OF TABLES

180 Degrees, Unscored, B-Flute, ZOO—lb
Test (Maximum Compression, Pounds per

Inch) . . . . . . . . .

135 Degrees, B-Flute, ZOO-lb. Test
(Maximum Compression, Pounds per

90 Degree, B-Flute, ZOO-lb. Test
(Maximum Compression, Pounds per

90 Degrees, B-Flute, ZOO-lb. Test
(Maximum Compression, Pounds per

45 Degrees, B-Flute, ZOO-lb. Test
(Maximum Compression, Pounds per

30 Degrees, B-Flute, ZOO-lb. Test
(Maximum Compression, Pounds per

iv

Inch)

Inch)

Inch)

Inch)

Inch)

Page

15

15

16

17

18

18

Figure

1.

LIST OF FIGURES

Page
Configuration of Test Specimen . . . . . . 9
Baldwin-Emery SR-4 Testing Machine Model FGT . ll

Baldwin Microformer Stress-Strain Recorder
Model MAlE . . . . . . . . . . . . 12

Graph of 90, 135, 45, 30, and 180 Degrees
Results . . . . . . . . . . . . . 19

Graph of Additional 90 Degrees Results . . . 20
Unscored (180 Degrees) . . . . . . . . . 23

Jig for Preparing Samples . . . . . . . . 28

CHAPTER I

INTRODUCTION

In the corrugated fibreboard industry, today, the
Mullen Burst Test is used, almost exclusively, to specify
the strength of corrugated board. Although the real
strength and protective qualities of corrugated board may
vary widely for the same test of board, the Mullen Burst
Test is still used because of transportation tariff regu-
lations, its ingrained nature in the industry and because
the Burst Test is "quick and easy." The opinion that the
burst strength of corrugated board is unsatisfactory as a
test method and is only very indirectly related to the
service strength of the end use of corrugated board, the
box, is widely held.1

If the standard by which corrugated board is rated,
today, is so ineffective, then what should the industry use
as a standard in rating and specifying corrugated board?

In the last ten to fifteen years many notable authorities

of the corrugated industry, including McKee, Gander,

 

lRobert George Bjornseth, "The Top to Bottom Com-
pression Strength of a Corrugated Container as a Function
of Flute Size and Relative Humidity Determined by Dead
Load" (unpublished M.S. thesis, Michigan State University,
1959).

Wachuta; Maltenfort; and Kellicut and Landt, have come out
in favor of using top-to-bottom compression tests as a
truer means of identifying corrugated fibreboard quality
and strength in actual use situations. "The top-to-bottom
resistance of corrugated boxes is a true test, well corre-
lated to properties of practical importance."2 According
to McKee, Gander, and Wachuta of the Institute of Paper
Chemistry, "Compression strength of a corrugated box is of
importance both as a partial indication of its warehouse
stacking performance and as an overall measure of the
quality of the fibreboard materials and conversion effi-
ciency."3

This concept of compression strength is much more
in line with the actual use of corrugated fibreboard and
containers, rather than the Mullen Burst Test. One of the
first objections raised when one discusses the replacement
of the Mullen Burst Test is that any test that replaces it
must be as easy to perform and the results of the board
quality must be ready quickly. Probably the most serious
limitation of the box compression test is that it is
generally not capable of distinguishing between the several

factors which contribute to box strength. In the event of

 

2Oivend Langaard, "Optimation of Corrugated Board
Construction with Regard to Compression Resistance of
Boxes," International Paper Board Industry (November,
1968).

3R. C. McKee, J. W. Gander, and J. R. Wachuta, "The
Why and How of Measuring Flexural Stiffness of Corrugated
Board," Paperboard Packaging (December, 1962).

 

inadequate box strength, for example, it may not be apparent
whether the fault lies with the component liners or corrugat—
ing medium, or the manufacture of the corrugated board, or
the conversion operations. Closely allied with this lack

of sensitivity to individual factors is the obvious short-
coming that the box test is so remote, in both time and
location, from the manufacture of the paperboard and
corrugated board, as to be of only limited value in the
quality control operations of the mill and corrugating
plant.4

Although the box compression strength test relates
much more closely with the containers actual potential,
the objections raised are valid from the manufacture‘s
standpoint. The introduction of the "edgewise compression
test" was and still is a property of major interest and
overcomes the objections of the box compression test.

By edgewise compression, reference is made to the
direction of the applied load, that is, parallel to the
plane of the liners, in contrast to the flat—crush test
where the compression is flat-wise. McKee gt_a1. attribute
the current interest in this property of combined board to
the facts that (a) box compression strength is dependent to
a large degree on the edgewise compression, (b) edgewise
compression strength may reflect certain fabrication effects

of corrugating, as well as the strength of the basic

 

R. C. McKee, J. W. Ganer, J. R. Wachuta, "Edgewise
Compressive Strength of Corrugated Fibreboard," Paperboard
Packaging (November, 1961), pp. 70-76.

 

 

materials and therefore is a realistic measure of one of
the qualities of corrugated board which govern top—load
compression, and (c) from a research standpoint, study of
combined board strength is a first step in a chain of
relationships linking box compression performance to

fibre properties.5 Oivend Langaard, of the Billeruds

 

Aktiebolag, Saffle, Sweden, writes on this subject ". .

 

the edge crush test is a theoretically sound method of
assessing the quality of corrugated board and should be
highly recommended for use instead of its bursting
strength."6

F.E.F.C.O., Federation Europienne de Cartons
Ondules, (European Corrugated Manufactures Association) in
1968 Published F.E.F.C.O. Testing Method No. 8, "Determina-
tion of the Edgewise Crush Resistance of Corrugated Board,"
which gives the exact test procedure and defines the
apparatus used to determine edgewise crush resistance of

corrugated fibreboard.7 Reference can also be found from

the Forest Products Laboratory, of the U.S. Forest Service

 

5R. C. McKee, J. W. Gander, J. R. Wachuta, "Com-
pression Strength Formula for Corrugated Boxes," Paperboard
Packaging (August, 1963), pp. 149-159.

 

 

6Langaard, op. cit.

7F.E.F.C.O., "Determination of the Edgewise Crush
Resistance of Corrugated Fibreboard," F.E.F.C.O. Testing
Method No. 8 (November, 1968).

at Madison, '

and from the Institute of Paper Chemistry
at Appleton, Wisconsin.

In the study to be presented, the author used the
procedures of F.E.F.C.O. Testing Method No. 8, previously
mentioned, with two minor exceptions.

This study was conducted with the objective of
determining what, if any, differences exist in edgewise
compression of corrugated fibreboard, when the angle of the
score was varied from an unscored, 180 degree, sample
through the angles of 135, 90, 45, and 30 degrees, perpen—
dicular to the compressive load. From the data collected,
an optimum compressive strength ratio of the length to
width (L/W) was also found. The study was not made to
give any specific figures, in pounds per linear inch,
although these figures do appear in the Tables of Chapter
III.

For this study, B-flute, ZOO-lb. test board was
used, because Moody, of the Forest Products Laboratory,
had found that B-flute corrugated fibreboard was both
theoretically and experimentally, to be higher in edgewise

compressive strength than either A- or C-flutes.lO

 

8R. C. Moody, "Edgewise Compressive Strength of Cor-

rugated Fibreboard as Determined by Local Instability," U.S.
Forest Service Research Paper, FPL-46, December, 1965.

9R. C. Moody and J. W. Konning, Jr., "Effect of
Loading Rate on the Edgewise Compressive Strength of Corru-
gated Fibreboard," U.S. Forest Service Research Note, FPL—
0121, April, 1966.

loMoody, op. cit.

CHAPTER II

EXPERIMENTAL PROCEDURE

Design of Study

 

The objective of this study was to determine the
differences that exist in edgewise compression of corrugated
board, when the angle of the score is varied from an
unscored, 180 degrees, sample through the angles of 135, 90,
45, and 30 degrees, perpendicular to the compressive load.
From this data a ratio or ratios of length to width (L/W)
for maximum compressive or stacking strength, could be
determined.

The study adhered to F.E.F.C.O. Testing Method No.
8, "Determination of Edgewise Crush Resistance of Corrugated
Board," in all aspects, except for the size of the specimen
and the speed of the platens. The size of the specimen was
changed to a board size of 12 inches by 12 inches, which
was felt would represent a corrugated box more realisti-
cally, than the 25cm. by 100cm. specimen suggested by the
test method. The speed of the platens was changed from
12.5mm. per minute to two inches per minute to accelerate

the testing, because of the numerous samples involved.

Preparation

 

All board used in the study was of the same lot and
was conditioned according to TAPPI Standard T402-m-49
(Temperature = 73:3.5 degrees F; Relative Humidity = 50:2%
and for not less than 24 hours). The corrugated board used
was B-flute, 200-1b. test.

To assure straight and parallel edges, perpendicular
to the flute direction and facings of the board, a jig was
constructed, as shown in the appendix. An Exacto Knife
was used to make the final cuts on the board, along the
edges to be compressed. The blade for the knife was changed
after each group of eighteen specimens.

Two guide fixtures were also cut from 3/4 inch
marine plywood, to fit the platens of the compression table,
with 1/8 inch grooves cut at angles of 90, 45, and 30
degrees. These fixtures were aligned and clamped to the

platens by means of Cbclamps.

Apparatus

 

The compression test machine or table used was a
Baldwin-Emery SR-4 (Model FGT) with the attached Baldwin

Microformer Stress-Strain Recorder (Model MAlE).

Test Method

 

As previously mentioned all corrugated fibreboard
used was conditioned prior to cutting and testing. All
testing was done under controlled conditions of 73i3.5

degrees F and 50i2% relative humidity.

Samples, 14 inches by 12 inches, were cut from flat
96 inches by 48 inches pieces of board. The samples were
then cut to the test size of 12 inches by 12 inches, by use
of the jig mentioned above. All edges of the specimens
used were parallel and square, with the board itself free
from converting marks and damage. All samples were scored
on a S&S Corrugated Paper Machinery Co. box making table.
For each group of specimens 18 samples were used,
to give a statistical base of 90 per cent (15%) accuracy.
All data was recorded on graph paper by the attached

recorder.

Compression Test

 

For each group of specimens, with the exception of
the unscored, 180 degree group, the samples were scored at
l, 2, 3, 4, 5, and 6 inches from the edge parallel to the
direction of the fluting. This made samples of 1"x11"x12",
2"x10"x12", 3"x9"x12", 4"x8"x12" and so on to a maximum of
6"x6"x12" (See Figure 1). This was done for each angle of
135, 90, and 45 degrees, making a total of 108 specimens
per angle. For the 30 degree angle only the 6"x6"x12"
series of samples were used, as explained in Chapter III.

For the right angle or 90 degree group, an addi-
tional series of samples, 1"x1"x12", 2"x2"x12", 3"x3"x12",
and so on to a maximum of 8"x8"x12" were also tested to
complete the data on the 90 degree angle.

As mentioned previously, the apparatus used for

the compression tests was a Baldwin-Emery SR-4 Testing

 

 

All x B" X C"

D = ANGLE

 

 

 

 

 

 

1+—

 

 

I

I

i
IJ/(D/

Figure 1.--Configuration of Test Specimen.

10

Machine and attached recorder, are shown in Figures 2 and
3.

The tests were run in five series, with each series
containing 108 samples, with the exception of the unscored
12"x12" group and the 30 degree group, which contained 18
samples, as explained in Chapter III.

The machine settings used for these tests, are as
follows:

Load Range . . . . . . . . . 1000 lbs.
Platen Speed . . . . . . . . 2.00 in/min.
Recorder Range . . . . . . . Full Range
Recorder Magification . . . . 1 to 3

The samples were placed in the holding fixtures and
aligned, so they were perpendicular to the direction of
loading. The recording pen was then zeroed and the compres-
sion test commenced. The machine was manually operated and
was shut down when compression had reached the board's fail—
ure point, with the recorder pen travelling back to the zero
point. The sample was then removed, the maximum compression
having been noted and recorded on the graph.

The test procedure just described was performed on
all samples. By using this procedure and recording the
maximum compression force, in pounds per linear inch, for
the different configurations, of the same board area,
height remaining constant, it was possible to formulate a
series of strength ratios based on the angle and the linear
length of the board, as it extended from the score.

The results, as shown in Chapter III, indicate there

is a considerable variation between angles and configurations

11

 

 

Figure 2.--Baldwin-Emery SR-4 Testing Machine Model FGT.

12

 

 

 

Figure 3.--Baldwin Microformer Stress-Strain Recorder Model
MAlE .

13

of length. There is also a leveling off point in the com—
pression strength, for all angles and configurations, from
which added board or extra length is extraneous and adds no

compression strength.

CHAPTER III

ANALYSIS OF DATA

In Tables 1 through 5 the analysis of the data is
given by recording the average of the specimens run and
the high and the low of the group. Table 4 records the
results of samples run with a 90 degree angle, 12 inches
in height, but with increasing linear inches in the ratio
of 1:1. The first sample is 1"x1"x12" and the size
increases to a sample size of 8"x8"x12". This extra data
was gathered to complete the information for the 90 degree
angle, which was found to be the angle that gave the

greatest compression strength.

Analysis of Test Results

 

The data from this study suggests a general pattern
for all the angles tested, that is, the compression strength
increases, then peaks and remains relatively constant. This
can be clearly seen in Figure 4, where the four graphs have
the same general shape. The compression strength of the
samples tested increased in a linear fashion (see Figure 5),
then leveled off. A slight increase in compression strength

after this point may be noted, due to the additional

14

TABLE l.--180 Degrees, Unscored, B-Flute, ZOO-lb. Test

15

(Maximum Compression, Pounds per Inch).

 

12"x12"

Average

High
Low

. . . . 51

60
4O

 

TABLE 2.--135 Degrees, B-Flute, ZOO-lb.
Compression, Pounds per Inch)

Test (Maximum

 

 

 

 

 

 

1"x11"x12" Average . . . . . 114
High . . . . . . . . 150
Low . . . . . . . . 9O

2"x10"x12" Average . . . . . 170
High . . . . . . . . 180
Low . . . . . . . . 150

3"x9"x12" Average . . . . . 194
High . . . . . . . 220
Low . . . . . . . . 175

4"x8"x12" Average . . . . . 209
High . . . . . . . . 230
Low . . . . . . . . 180

5"x7"x12" Average . . . 200
High . . . . . . . . 230
Low . . . . . . . . 170

6"x6"x12" Average . . . . . 218
High . . . . . . . . 235
O O O O O O O O 170

LOW

 

16

TABLE 3.--90 Degree, B-Flute, ZOO-lb. Test (Maximum
Compression, Pounds per Inch).

 

 

 

 

 

 

1"x11"x12" Average . . . . . 134

High . . . . . . . 160

Low . . . . . . . 100
2"x10"x12" Average . . . . . 192

High . . . . . . . 210

Low . . . . . . . 170
3"x9"x12" Average . . . . . 210

High . . . . . . . 225

Low 0 O O O O O O 190
4"x8"x12" Average . . . . . 218

High . . . . . . . 245

IDW .. O O O O O O 185
5"x7"x12" Average . . . . . 224

High 0 O O O O O O 260

Low 0 O O O O O O 190
6"x6"x12" Average . . . . . 222

High . . . . . . . 250

LOW O O O O O O O 195

 

TABLE 4.--90 Degrees, B-Flute,
Compression, Pounds per Inch).

17

ZOO-lb. Test

(Maximum

 

1"x1"x12"

Average

High
Low

70
45

 

2"x2"x12"

Average

High
Low

135
110

 

3"x3"x12"

Average

High
Low

160
140

 

4IIX4IIX12"

Average

High
Low

195
165

 

5" x5 "x12"

Average

High
Low

230
190

 

6llx6 "x12"

Average

High
Low

250
195

 

7"x7"x12"

Average

High
Low

225
200

 

8"x8"x12"

Average

High
Low

230
220

 

18

TABLE 5.--45 Degrees, B-Flute, ZOO-lb. Test (Maximum
Compression, Pounds per Inch).

 

1"x11"x12" Average . . . . . 114

High . . . . . . . . 140
Low . . . . . . . . 95

 

2"x10"x12" Average . . . . . 158

High . . . . . . . . 185
Low . . . . . . . . 130

 

3"x9"x12" Average . . . . . 165

High . . . . . . . . 225
LOW O O O O O O O O 140

 

4"x8"x12" Average . . . . . 173

High 0 O O O O O O O 185
Low I O O O O O O O 160

 

5"x7"x12" Average . . . . . 179

High . . . . . . . . 225
Low . . . . . . . . 140

 

6"x6"x12" Average . . . . . 187

High . . . . . . . . 225
Low . . . . . . . . 160

 

TABLE 6T--30 Degrees, B-Flute, ZOO-lb. Test (Maximum
Compression, Pounds per Inch).

 

6"x6"x12" Average . . . . . 142
High 0 O O O O O O O 165
Low 0 O O O O O O O 130

 

1See explanation in analysis text.

19

.mufismmm mmmnmma oma 8cm .om .me .mmH .om mo sawhoun.e mnsmflm.

 

 

 

 

 

 

m m D O m <
O V
“mammoma om: 83082.3 as am
OOH
“I! .
=NHX=NH H U h OWH
=NHX:@N=© H h
=NHN=BX:m H W O
:NHX:®X=V H 0 § .
..N._an..mu.n=m H U
=NHX:OHX=N H m D O
I o N
=NHX:HHX=H I fl 6 D O
mmmummo cm H or o
mwmummo me u
wwwummo mmau
mmmumoo om u 0mm

 

LBS. / LINEAR INCH

20

A

B

C

D

E

F

G

H
250
200
150

    

lOO

HDNI HVENII / 'Sfil

50

 

 

Figure 5.--Graph of Additional 90 Degrees Results.

lllxlllxlzll
ZIIXZIIXlZH
3"x3"x12"
4HX4IIX12"
5"x5"x12"
6"x6"x12"
7"x7"xl2"
8"x8"x12"

ANGLE = 90 DEGREES

21

material present and not to any inherent strength capacity
of the board.

The 90 degree or right angle gave the greatest com—
pressive strength, followed by the 135 degree, 45 degree,
and 30 degree angles. The 30 degree angle was only tested
at the 6"x6"x12" configuration, because it had become
apparent that the 90 degree angle was the optimum and only
a one to one ratio in the 30 degree angle was needed to
complete the information.

In this study it was determined that the greatest
compression strength occurred when the ratio of length to
width (L/W) was between 1.20 and 1.40. With a L/W ratio of
1.00 (6"x6"x12"), it was found that a leveling off of the
compression strength commenced. The findings of this study
agree most favorably to one of S. S. Mirasol, Jr.,11 who
found that a length to width ratio (L/W) of between 1.25
and 1.50 gave the highest compression strength in corru-
gated boxes. He also found as the L/W ratio increased to
2.00 the compression strength dropped considerably from
the L/W ratio of 1.00 or a square. Keep in mind that the
Mirasol study was concerned with complete corrugated boxes,
while this study dealt with scored pieces of corrugated
board, yet the findings of both studies concur quite

closely.

 

llSalustiano S. Mirasol, Jr., "Evaluation of Some
Existing Empirical Equations for Top-to-Bottom Compression
Strength of Corrugated Fibreboard Boxes" (unpublished
M.S. thesis, Michigan State University, 1966).

 

 

22

At the same time this study was being conducted,
another study12 was being made on varying column heights
of corrugated board. The column height was varied from
12 inches, the same height as used in this study, to 24
inches, with an 18 inch intermediary, using B-flute, 200-
1bs. test board. The results of this study gave further
correlation to the results found herein and also found
that the Rankine Formula, the typical formula for short
columns, can be used to predict the edgewise compressive

strength for interior corrugated packing pieces.

 

lzTani, "Compressive Strength of Corrugated Board
Columns" (unpublished study for the School of Packaging,
Michigan State University, 1972).

50

40

30

20

10

23

 

Unscored (180 Degrees)

    

 

0 2 4 6

Inches

Figure 6.--Unscored (180 Degrees).

12

CHAPTER IV

CONCLUSIONS

From this study and others related to the compres-
sive capacity of corrugated fibreboard, it can be stated
that the maximum compression strength occurs when the
angle of the score is 90 degrees and the length to width
(L/W) ratio is between 1.20 and 1.50. This information can
be applied to the design of interior packing, such as
partitions, dividers and corner protectors and to the
corrugated case itself. In a time when all are concerned
with ecology and the preservation of our natural resources,
the utmost should be done to step the over use of needless
packaging materials through efficient package design.

As a final comment, the author acknowledges the
limited depth of this study, due to time requirements, but
it is hoped that this work may be a basis from which fur-
ther studies can be conducted, so a sound test and speci-
fication system may be set up to replace the outdated and

inadequate Mullen Burst Test.

24

BIBLIOGRAPHY

25

l9

.mnasmmm mmmumma owe ecu .om .me .mma .om Lo gamuwuu.e ousmflm

 

 

Ammmmuma omfl .Qmmoomzsv one

=NHX=NH
=NHN=WX=©
:Nax=hx=m
=NHN:®N:V
=NHN=mX=m
=NHx=oax=N
=NHX=HHN=H H

II II
«muommo

 

 

mmmummo om
mmmummo mv
mmmumma mmau
mwmumma cm H

 

0m

00H

on”

com

0mm

LBS. / LINEAR INCH

20

  

 

llleHXlZH
lelelxlzll
3IIX3NX12II
4IIX4IIX12"
5"x5"x12"
6IIX6IIX12"
7IIX7HX12"
BIIXBIIXlZH

A:
B:
C:
D:
E:
F:
G:
H:
250 '
200
E
U)
\\ 150
E
g ANGLE = 90 DEGREES
§n
H
:2 100
C]
21‘.
50
O

 

Figure 5.--Graph of Additional 90 Degrees Results.

21

material present and not to any inherent strength capacity
of the board.

The 90 degree or right angle gave the greatest com—
pressive strength, followed by the 135 degree, 45 degree,
and 30 degree angles. The 30 degree angle was only tested
at the 6"x6"x12" configuration, because it had become
apparent that the 90 degree angle was the optimum and only
a one to one ratio in the 30 degree angle was needed to
complete the information.

In this study it was determined that the greatest
compression strength occurred when the ratio of length to
width (L/W) was between 1.20 and 1.40. With a L/W ratio of
1.00 (6"x6"x12"), it was found that a leveling off of the
compression strength commenced. The findings of this study
agree most favorably to one of S. S. Mirasol, Jr.,11 who
found that a length to width ratio (L/W) of between 1.25
and 1.50 gave the highest compression strength in corru-
gated boxes. He also found as the L/W ratio increased to
2.00 the compression strength dropped considerably from
the L/W ratio of 1.00 or a square. Keep in mind that the
Mirasol study was concerned with complete corrugated boxes,
while this study dealt with scored pieces of corrugated
board, yet the findings of both studies concur quite

closely.

 

11Salustiano S. Mirasol, Jr., "Evaluation of Some
Existing Empirical Equations for Top-to-Bottom Compression
Strength of Corrugated Fibreboard Boxes" (unpublished
M.S. thesis, Michigan State University, 1966).

 

 

 

 

22

At the same time this study was being conducted,
another study12 was being made on varying column heights
of corrugated board. The column height was varied from
12 inches, the same height as used in this study, to 24
inches, with an 18 inch intermediary, using B-flute, 200-
1bs. test board. The results of this study gave further
correlation to the results found herein and also found
that the Rankine Formula, the typical formula for short
columns, can be used to predict the edgewise compressive

strength for interior corrugated packing pieces.

 

12Tani, "Compressive Strength of Corrugated Board
Columns" (unpublished study for the School of Packaging,
Michigan State University, 1972).

50

4O

30

20

10

23

 

Unscored (180 Degrees)

    

 

0 2 4 6

Inches

Figure 6.--Unscored (180 Degrees).

12

CHAPTER IV

CONCLUSIONS

.From this study and others related to the compres-
sive capacity of corrugated fibreboard, it can be stated
that the maximum compression strength occurs when the
angle of the score is 90 degrees and the length to width
(L/W) ratio is between 1.20 and 1.50. This information can
be applied to the design of interior packing, such as
partitions, dividers and corner protectors and to the
corrugated case itself. In a time when all are concerned
with ecology and the preservation of our natural resources,
the utmost should be done to stop the over use of needless
packaging materials through efficient package design.

As a final comment, the author acknowledges the
limited depth of this study, due to time requirements, but
it is hoped that this work may be a basis from which fur-
ther studies can be conducted, so a sound test and speci—
fication system may be set up to replace the outdated and

inadequate Mullen Burst Test.

24

BIBLIOGRAPHY

25

BIBLIOGRAPHY

Bjornseth, Robert George. "The Top-to-Bottom Compression
Strength of a Corrugated Container as a Function
of Flute Size and Relative Humidity Determined by
Dead Load." Unpublished M.S. thesis, Michigan
State University, 1959.

F.E.F.C.O. "Determination of the Edgewise Crush Resistance
of Corrugated Fibreboard. F.E.F.C.O. Testing Method
No. 8, November, 1968.

Langaard, Oivend. "Optimation of Corrugated Board Con-
struction with Regard to Compression Resistance
of Boxes." International Paper Board Industry,

 

November, 1968.

McKee, R. C.; Gander, J. W.; and Wachuta, J. R. "Edgewise
Compressive Strength of Corrugated Fibreboard."
Paperboard Packaging, November, 1961, pp. 70-76.

 

McKee, R. C.; Gander, J. W.; Wachuta, J. R. "The Why and
How of Measuring Flexural Stiffness of Corrugated
Board." Paperboard Packaging, December, 1962.

 

McKee, R. C.; Gander, J. W.; Wachuta, J. R. "Compression
Strength Formula for Corrugated Boxes." Paper-
‘ board Packaging, August, 1963, pp. 149-159.

 

Mirasol, Salustiano 8., Jr. "Evaluation of Some Existing
Empirical Equations for Top-to-Bottom Compression
Strength of Corrugated Fibreboard Boxes." Unpub-
lished M.S. thesis, Michigan State University,
1966.

Moody, R. C. "Edgewise Compressive Strength of Corrugated
Fibreboard as Determined by Local Instability."
U.S. Forest Service Research Paper, FPL-46,
December, 1965.

Moody, R. C. and Konning, J. W., Jr. "Effect of Loading
Rate on the Edgewise Compressive Strength of Cor-
rugated Fibreboard." U.S. Forest Service Research
Note, FPL-0121, April, 1966.

26

APPENDIX

27

28

WOODEN STOP

IRON BARS
\ ’
DIRECTION OF FLUTING

. r
. '

.h.‘.£:!m

    
  
 

SLOT WIDTH =
BLADE THICKNESS

Figure 7.--Jig for Preparing Samples.

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