TMA Q Series Getting Started Guide
36
Calibrating the TMA
To obtain accurate experimental results, calibrate the TMA when you first install it. To keep your TMA
working to the highest level of performance possible, you should calibrate periodically thereafter. A brief
description of each calibration is outlined below. For details on how to perform that calibration, refer to the
online help documentation accessed through the instrument control software.
Force Calibration
Force calibration calibrates the force exerted by the probe on the sample during experiments using three
different mass values (0, 50, and 100 grams) and can be performed with any probe in place on the instrument.
The first calibration point is 0 grams. You may use weights other than the recommended 50 and 100 grams, if
desired (up to 100 grams is allowed). For example, you can use 10 grams for force calibration if only low
forces will be used in subsequent experiments.
This calibration should be performed periodically (approximately once a month) and can be performed from
the TA instrument control program or the instrument's touch screen.
NOTE: A force calibration performs the functions of a probe calibration (see the next sec-
tion). Therefore, it is not necessary to perform a probe calibration immediately following a
force calibration.
Probe Calibration
This procedure, sometimes called “initializing,” is used to calibrate zero force, the LVDT, and the probe's
compliance. It corrects for any difference in the different probes used on the TMA and should be done every
time you change a probe on the TMA. This calibration can be performed from the TA instrument control
program or the instrument's touch screen.
Temperature Calibration
Temperature calibration is based on a run, conducted in the calibration mode, in which a temperature stan-
dard (e.g., indium) is heated through its melting point. The recorded melting point of this standard is com-
pared to the known melting point, and the difference is calculated for temperature calibration.
In addition, you can use up to four other standards to calibrate temperature. If you use one pair of known
and observed points, the entire curve is offset, or shifted, to the actual melting point. If you use multiple
standards, the temperature is corrected by a cubic spline fit between the points with fixed offset values
beyond the calibration window. This can create a small discontinuity in the heating rate. The multiple-point
temperature calibration is more accurate than the one-point calibration.
For all probe types except the film/fiber accessory, small flattened pieces of standard metals are placed on
the stage. To protect the stage from amalgamation with the metal, it is recommended that aluminum or
platinum be placed between the stage and the metal standard. The end of the probe can also be wrapped with
foil for added protection.
For the film/fiber probe, metal wires can be crimped into the aluminum balls and used for calibration.
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