|
How
often, and is it necessary to have my Stiffness Tester calibrated?
To
determine if the Taber Stiffness Tester is operating correctly,
a calibration check should be conducted prior to each use. Spring
steel specimens with an average stiffness result scribed on them
are used as the standard for this purpose. If the stiffness reading
of the standard varies more than plus or minus 1% of full scale
[± 1 stiffness unit of the 100 unit range; ± 5 stiffness
units of the 500 unit range; ± 10 stiffness units of the
1000 unit; etc.], the instrument must be returned to the factory
for calibration.
To
ensure your instrument is operating optimally and within specifications,
Taber recommends annual factory calibration.
What maintenance is required?
All
Taber Stiffness Tester bearings and gears are grease lubricated
and sealed at the factory. If properly stored and handled, this
precision instrument does not require regular maintenance.
How should specimens be prepared?
To
ensure repeatable results, sample size must be uniform. The Triple
Cut Specimen Shear accurately prepares specimens of most material
into the proper configuration (1 ½" x 2 ¾"
or 1 ½" x 1 ½"). This accessory instrument
handles paper or plastic up to 0.020" thick in addition to
thin metallic sheet and foil.
What is the maximum specimen thickness I can test?
With
the ratchet stop roller (included on all new instruments), the
Stiffness Tester will accommodate specimen thickness up to 0.291".
However, regardless of material thickness, if your material exceeds
10,000 Stiffness Units you will need to find an alternative method
to test it.
Can I test wire or tubing on the Taber Stiffness Tester?
Using
the Tube Testing Apparatus, you can test medical tubing, plastic
tubing and wire up to 4mm in diameter. A top and bottom gauge
block (drilled to your specifications) is provided which eliminates
the crushing factor.
How do I test lightweight materials?
The
Sensitivity Range Attachment must be used to test extremely lightweight
materials such as cellophane, natural / synthetic fibers, thin
paper, metallic foils.
How do I determine what range to test?
A
set-up chart is provided with each instrument to help determine
which test range should be used for the type of material being
testing. When a range needs to be determined for the first time,
test a sample in range 3. If the sample deflects immediately and
results in a very low stiffness reading of less than or equal
to 10 stiffness units, change to range 2. If the results are greater
than or equal to 100, use ranges 4 - 9.
Values
of test ranges overlap. For best accuracy, test in lowest range.
Can I test specimens that are curved (have memory)?
Some
materials have a curvature. If the curvature will allow you to
"balance and zero" the pendulum properly, then successful
testing of that sample can occur. If not, you must select a different,
flatter sample. It is important that the test strips are as straight
as possible before inserting them into the instrument for testing.
However, do not attempt to straighten a curved sample.
My results are different than expected?
The
extreme sensitivity of the Stiffness Tester magnifies variations
in the material. Therefore, it is recommended that 5 or more samples
be tested and the average result taken as the stiffness rating.
Variations in testing may also result from the way in which the
specimen is clamped or how clearances are adjusted between the
rollers and specimen. It is important to note:
- Do
not flex a sample prior to testing.
- Be
careful not to crush the sample by overtightening the clamps.
- Excessive
compression of the sample will reduce the material's thickness
thereby resulting in stiffness readings that are both inconsistent
and inaccurate due to a reduced cross sectional area at the
clamp.
If the
test results of several instruments operated by different technicians are to be compared, then a correlation factor
should be used as a multiplier for actual results obtained with
the instrument at the time of testing [Correlation Factor = Value
on Calibration Specimen / Average of test results taken by the technician
using the Calibration Specimen].
The reading for one side is higher than the other?
Some
materials have an inherent grain derived from their manufacturing
process. This will typically affect the stiffness and must be
accounted for during the test procedures by testing those samples
in both directions. It is advisable to prepare and test 5 to 10
specimens in each grain direction for testing.
Can I download information to a PC?
The
150-E includes a RS-232 port that allows you to download test
data in either text format (recognized by Dbase, Excel, Quattro,
etc) or delimited format. Both test set-up and statistical data
can be downloaded.
Click here for Instructions (.doc file - MS Word Format)
Does humidity affect results?
Moisture
sensitive materials should be conditioned for at least 24 and
preferably 72 hours in a temperature and humidity-controlled environment
to ensure consistency during testing.
What are Taber Stiffness Units?
Taber
Stiffness Units (g · cm) are the unit of measurement that
results after the test material has been deflected to the left
and right and the average is calculated.
|
