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The
softening point of a glass is the most widely used production
control parameter. Changes in the softening point temperature are
indications of chemistry changes. According to ASTM C-338 the softening
point temperature is the temperature at which a uniform fiber of glass
(0.65 mm in diameter by 23.5 cm long) elongates under its own weight at
a rate of 1.0 millimeters per minute when the upper 10 cm of its length
is heated in a special furnace at the rate of 5°C per minute. This
test is performed in a laser optic extensometer system that is manufactured by
Orton. The Orton Model SP-1000
Series has been designed to
automatically monitor the elongation of the sample fiber and calculate
the Littleton softening point according to the ASTM C-338 method.
(Note: If forming a fiber is not desired, is impractical, or impossible, the softening point temperature RANGE can still be determined by the Parallel Plate Viscometer method, ASTM C-1351M.)
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It takes 5 minutes
to measure the Littleton Softening Point of a glass
fiber. It’s simple. After the test fiber is pulled to meet the ASTM
C-338 specified dimensions, the operator places the fiber into the
preheated furnace, aligns the fiber in the laser path, clicks the start
button in the software screen display, and walks away. The system does
the rest. The operator is free to perform other tasks. Five minutes
later, the operator returns and reads the Littleton Softening Point
Temperature on the computer monitor. It's that easy. Model SP-1000
automatically calculates the rate of elongation and displays the
softening point temperature which eliminates operator differences,
operator judgments, operator biases, and errors. Model SP-1000
is a FAST, EASY, ACCURATE, RELIABLE,
and REPRODUCIBLE instrument for
R&D and for QC checks on batch chemistry changes.
EASY: The operator
requires little training. After
the test fiber is pulled to meet the ASTM specified dimensions, the
operator simply places the fiber into the furnace, aligns the laser,
clicks the START button on the computer monitor, and walks away. The
operator is free to perform other tasks.
FAST: In less than five
minutes the Littleton
Softening Point Temperature is displayed on the computer monitor. It is
possible for one operator to test 50 fibers during a single 8-hour
shift.
ACCURATE, RELIABLE,and
REPRODUCIBLE: The laser system
automatically monitors the
elongation, the computer calculates the rate of elongation, and the
computer determines the softening point temperature. Operator
differences, errors, and biases are eliminated. With good fibers,
±1°C is routine.
FLEXIBLE: The user can
select the ASTM C-338
procedure, or modify the thermal cycle for individual testing
requirements, such as high volume QC testing.
POWERFUL: The data
acquisition software displays the
test and conditions while the test is underway. The data review
software shows the test results, and generates a report that
automatically calculates the average temperature for a series of
fibers.
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