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519 U/L – P type (upper/lower), 520 U/L – J type (upper/lower) 2.0 e
Lorentzen & Wettre
L&W AUTOLINE bursting strength (p and j)
Benefits
• Possible to compensate for the
diaphragm’s own stiffness
• Robust C-design to withstand
strong forces (clamping forces
can be up to 5000 N (730 psi)
• Extra holder for quick and easy
change of diaphragm
• The module is based on the
same measuring technology
as our stand alone instrument
– L&W Bursting Strength Tester
L&W Autoline Bursting Strength,
code 519 L (P-type).
L&W Autoline Bursting Strength,
code 520 U (J-type).
L&W Autoline Bursting Strength module measures bursting strength from the bottom side,
or top side of paper and paper board. Bursting strength (Mullen test) is a traditional measurement
of paper strength.
Bursting strength tests are typically performed
on papers and boards used in packaging – it
is a measurement of a sample’s resistance to
rupturing. Bursting strength is a function of
various processes performed in the papermaking
process. Increased use of fillers decreases
bursting strength, while increased use of longer
fibres and surface sizing increases a paper’s
bursting strength. L&W Autoline Bursting
Strength measures bursting strength of a paper
or board from the bottom or top side of a
sample, and the module is available in different
versions depending on the sample (P-model for
paper, and J-model for board).
•L&W Autoline Bursting Strength,
code 519 – upper/lower for paper
•L&W Autoline Bursting Strength,
code 520 – upper/lower for board
Measurement results
Three different test results can be reported
after a single measurement; standard bursting
strength, compensated bursting strength, and
bursting energy absorption (BEA).
Compensated bursting strength
For low bursting strength levels, the stiffness of
the diaphragm can account for a large portion
of the bursting strength value. If desired, the
system can report effective bursting strength,
compensated from the effects of the diaphragm.
Bursting Energy Absorption (BEA)
BEA is used to determine the energy absorption
capability of a material. Strong, flexible
paper has higher energy absorption values,
while brittle and stiff paper has lower values.
L&W Autoline Bursting Strength reports BEA
according to the SCAN P 24 standard (applies
to the paper version).
Measuring principle
The test piece, placed over a circular elastic
diaphragm, is rigidly clamped at the periphery
but free to bulge with the diaphragm (see sketch
next page). Hydraulic fluid is pumped at a
constant rate, bulging the diaphragm until the
test piece ruptures. The bursting strength of the
test piece is the maximum value of the applied
hydraulic pressure.
Lorentzen & Wettre
Specification
METHOD
Description:
Bursting strength is defined as the maximum uniformly
distributed pressure, applied by an elastic diaphragm
square to the paper surface that the paper can withstand
without breaking.
Bursting Energy Absorption (BEA) is the total work done
per unit area of a paper or board when it is stretched to
rupture. Bursting energy absorption is expressed in J/m².
P = hydraulic pressure during measurement
V = volume acting on the test piece
BEA = A1/a2
A1 = area under the pressure/volume curve
a2 = area of opening in the bursting strength tester
L&W Autoline Bursting Strength,
– code 519 U, P-type, upper (bursting strength from top side)
– code 519 L, P-type, lower (bursting strength from bottom side)
– code 520 U, J-type, upper (bursting strength from top side)
– code 520 L, J-type, lower (bursting strength from bottom side)
Measurement range P-type (paper): 70–2000 kPa (10–290 psi)
J-type (board): 170–5000 kPa (25–725 psi)
Clamping force
Adjustable between:
1000–6000 N (225–1350 psi)
Applicable standards P-type: APPITA AS 1301.403, BS 3137,
JIS 8112, PAPTAC D.8, ISO 2758, SCAN P24,
TAPPI T403
J-type: APPITA AS 1301.438, ISO 2759,
SCAN P25, TAPPI T807
P
A1
Clamping device
V
Use:
Bursting is a method with a very long tradition and is
considered to be a general indicator of the strength
and toughness properties of paper. Bursting strength
are common in the product specification for different
packaging grades such as linerboard and sack paper.
Test piece
Diaphragm
Control:
Bursting strength increases, for example, with grammage/
basis weight, wet pressing, MD/CD ratio and refining.
Liquid
A basic sketch of the measuring head.
L&W Autoline Bursting Strength mounted together with
L&W Autoline Tearing Strength in the same module
(code 582 – a common combination module).
An extra diaphragm holder for quick change of the diaphragm,
and a bulge height template for verification of the diaphragm
stiffness are supplied in an accessory case.
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