tear-tester0 pages

tear tester
83-20-00, 83-21-00t
FEATURES
• Automatic specimen notching
• Mechanical-pneumatic clamping avoids
sample slippage to ensure repeatable results
• Automatic pendulum reset with lifting device
• Tearing force displayed digitally
• RS-232 data output
• Small, table-top instrument
• Maintaining a uniform quality level
• Safety Hood protects operator from injury
while pendulum is in motion.

TEAR TESTING
Tear testing measures the force required to
continue the tearing of an initial cut in sheet
materials. Models and weights are available to
test material with a variety of strengths. This is
also useful to evaluate strength of perforated
materials.
Also known as the Elmendorf test, the tearing
test has been performed in the paper industry for
more than half century in order to measure the
mean internal resistance of cellulose or papers to
the propagation of a deliberately initiated tear. It
enables rapid determination of the dynamic resistance of materials designed to be subjected to
strong shearing loads (e.g. newspaper) or liable
to be damaged by sharp or heavy objects (e.g.
paper bags, seat belts, protective clothing).
Subsequently, the test was naturally adopted for
all materials in the form of sheet or films, cardboards, cloth, knitted fabrics, plastic films, aluminum foil, non-woven fabrics, complex flexible
packaging etc. for which the service requirements
are similar to those for paper.

OPERATION
The test is carried out on a specimen composed
of one or more samples of standard dimensions, usually with a distance of 1.7 in (43mm)
remaining to be torn after initiating the tear. The
energy of a pendulum of suitable weight is used
to completely tear the specimen. The difference in
the angle from the vertical of the center of gravity of the pendulum between the downswing and
the upswing is a measure of the energy absorbed
in tearing the sample. This angular movement
is measured with a digital encoder and is immediately converted to the mean tearing force for a
single sheet by the microprocessor incorporated in
the apparatus.

▲ Shows Testing Apparatus in motion