Diagrams for documentation and quality analysis Screenshot TkGraph graphics program From the result files, the graphics software generates plots of completed tests serving to document measuring series and single measurements and forming the basis for a quality analysis which makes the most frequent error sources visible to the user. The Summary Plot gives an overview of the measuring series, additional detailed diagrams (Single Measurement Plots) assist with analyzing the single measurements. Here are some examples how to apply this powerful tool:

Summary Plot: scatter of a measuring series TC diagrams with low and high scatter TK04 tests are organized as measuring series, because the scatter of such a series can indicate thermal disturbances (like instable ambient temperatures) or improper measuring parameters (e.g. too low heating power). Under optimal conditions, the scatter will often stay below ± 0.5% (top). If it reaches ± 5% (bottom) you should check the measuring conditions. To be able to use this information, we recommend measuring series consisting of 3 to 10 single measurements (executed completely unattended by TK04).

Summary Plot: position of evaluation intervals Measuring series with short and with long evaluation intervals The evaluation algorithm automatically determines the optimal time interval of each single measurement for thermal conductivity determination (i.e. the part of the measuring data best resembling the ideal and undisturbed theoretical temperature rise). If these intervals are very short and/or are positioned relatively late in the temperature rise (top), this points to thermal disturbances, bad contact between probe and sample or too small probe sizes. In a good measuring series the intervals are long and are starting early (bottom).

Summary Plot: number of solutions Number of solutions decreasing during measuring series The software not only calculates a single thermal conductivity value from the optimal evaluation interval of each measuring curve, but additionally from all intervals exceeding a minimum LET value. The more intervals fulfill this condition, the better the quality of the measuring data. In a measuring series the number of solutions per single measurement should be relatively constant (top). If the number of solutions calculated from the single measurements is generally low, or is strongly fluctuating within a measuring series, the contact between probe and sample is bad or external thermal disturbances are present. If the number of solutions decreases in the course of a measuring series, the sample is too small (bottom, the heat wave is reflected at the sample boundaries and disturbs the subsequent temperature measurements).

Single Measurement Plot: LET versus thermal conductivity Good measurement / bad contact / reflection from sample boundary If the LET values of all evaluated intervals of a temperature curve are plotted versus thermal conductivity, undisturbed measurements show a characteristic asymptotic pattern (left diagram). All deviations from this distribution indicate disturbances, whereas from the type of deviation conclusions may be drawn as to the type of disturbance (middle: unsufficient contact between probe and sample, right: reflection of the heat wave at the sample boundary).

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