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Development
of Automated Testing:
Manual and Automated Testers
Relationship of Burst to Pull/Peel Tensile Testing
ISO 11607: Note 24
 Looking
at an early ARO tester, you see an Analog gauge
and a manual pressure regulator. The operator
would turn the pressure regulator to increase
the pressure and flow output until the package
burst. The operator would observe and write the
result. The test while credible for its time was
dependent on operator skill and repeatability.
By changing the rate of inflation by the operator
test results could be altered significantly. The
analog gage had response time measured in seconds
or, at best, fractions of a second and required
manual logging of data, which is subject to transposition
and other errors.
This
is a picture of the T.M. Electronics BT-100. In
1986, T.M. Electronics introduced the first electronic
automatic package tester and read out system.
From this picture you see that several advances
were made in instrument design and process use.
First, the detector and readout are electronic.
The use of electronic based transducers moved
the instrument from the analog time domain of
seconds to the digital domain of milliseconds.
The speed of response of the instrument was now
consistent with the dynamic nature of the burst
test.
Another
significant addition to the test process was control
of flow rate by means of a regulating valve. We
believe that the flow rate was equivalent to the
pull rate of the tensile test. The rate of application
of the force to the package could influence the
results of the test. Furthermore, the addition
of flow control would produce a more repeatable
test by removing the operator variability from
the test process.
Control
of timing and valve pneumatic functions of the
test was incorporated by the digital programming
built into the circuits of the instrument.
Finally,
hard copy results were now available via a printer
or RS232 output, thus preventing recording errors
by the operator. The automatic operation also
provided speed and regularity to the test process.
 A
look at a current version package tester, called
the BT-1000 shows that the design has increased
its automation in pressure and flow regulation
while simplifying the use of the machine with
ATM style prompts for programming. The addition
of a graphic display provides more information
at the fingertips of the user.
During
this same time period, many people wanted to correlate
the burst test with the classic tensile pull/
peel test. Attempts were made to create an algorithm,
but soon it became apparent that the mechanics
of the two tests were not compatible for this
correlation. It is true that some manufacturers
have developed a correlation that they are comfortable
with. However, due to the number of variables
in geometry, materials and adhesives no general
correlation has been developed.
In
fact, the new draft ISO 11607 standard makes note
of the lack of correlation in the burst or creep
and the tensile pull/ peel test. Note 24 of the
standard specifically states that there in no
generally accepted correlation in these measurements.
This paper is presented courtesy
of TM Electronics, Inc.
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