Calibration System for FUJIFILM Prescale
FUJIFILM’s pressure sensitive Prescale film is an important tool for the determination of contact pressure. It is ideal for fast qualitative evaluations, as for quantitative measurement, control experiments should to be done prior to the measurement, which are then transferred to calibration curves.
Tiedemann has developed a calibration system, which includes all necessary tools:
– Calibration Plunger KV with two cylindrical, plain-polished plungers with well know front areas to press the material sample and the film
– Compression Device BELV, individually equipped with a Tiedemann ring dynamometer
– Hand Cutting tool SV to cut the Prescale film in the diameter of the Calibration Plunger KV
– Punching toll PV to cut thicker structural material in the diameter if the Calibration Plunger
Calibrations with Different Press Materials
The Tiedemann calibration system is made for smooth surface pressures as well as structured surrounding materials like grids or carpets. In such a case, the structure is visible on the films as well. The impression is difficult to evaluate, therefore it is recommended to place the film between these structured materials during calibration to generate an individual calibration curve for this material.
Execution of the Calibration System
Find the Right Combination of Tools
A basic configuration for surface compressions up to 50 MPa is the Compression Device BELV. Further, you choose the right Tiedemann dynamometer, the KV Calibration Plunger device plus optional the SV Hand Cutter tool. Whether a PV Punching Tool is recommended depends on the ambient structural materials. At surface pressures above 50 MPa, we must refer to your own press.
CALTEST Calibration and Evaluation Program
The Tiedemann Calibration and Measurement Program CALTEST is an intuitive Windows compatible program that generates calibration curves from the results of the calibration device and offers analysis using these curves.
In addition, the program already includes calibration curves for smooth surfaces at room temperature and various humidity levels for a special DIN A3 scanner defined by us. The calibration curves are valid for 1 min press duration.
Individual calibration curves for quantitative measurements at longer or shorter press durations, higher temperatures or on structured surfaces such as cardboard, lattice surfaces, nub structure or fabric structures differ significantly from those of smooth surfaces and must be created by the user.
To create the calibration curves, appropriate impressions are made with the tools from above, which are subject to the same conditions as in the subsequent measuring process.
The results are recorded by the flatbed scanner and coupled with the mechanical pressure values to a calibration curve. Various parameters are included in the calibration curve, the pressure, the humidity, the temperature, the surface and the contact time. A suitable name can be assigned to the calibration curve to be stored. To create a calibration curve, at least five measuring points should be available, each at the edges of the measuring range of a film and three further equidistant points over the measuring range. However, further points increase the accuracy. As soon as the calibration curve has been created, it can be used for the evaluations.
Extension of the measuring range
If the expected pressure distribution cannot be covered by the measuring range of a film, several types of film can be superimposed in order to increase the measuring range. The following evaluation shows a simultaneous pressing of several pressure measuring foils for different measuring ranges, which were superimposed.
Evaluations with CALTEST
The analysis program offers all tools necessary for the evaluation. Individual points can be clicked with the mouse, areas can be zoomed in and sectional images can be created. The scans can be displayed in original colours or also in false colours for better differentiation.
The corresponding calibration curve is used for quantitative evaluation. The entire scan or parts of it can be analysed as a whole. Areas of interesting regions can be framed by given geometric shapes like circle or rectangle or as freehand curve. The values within the frame are listed as shown on the right.
In addition to sections and the determination of the pressure values within the section, the surface pressure results can also be determined with pinpoint accuracy.
For this purpose, points can be selected with the mouse in the overall image or in the sections. The pressure value then appears directly next to the selected measuring point.
Precise determination of pressures
A further analysis option is sectional views of the printed image. CALTEST offers numerous variants for this purpose. In addition to the simple intersection line in all directions, there is the option for filtering the noise by a chain or rectangular line.
The straight line as cut is possible in any direction and results in an exact cut with the respective information about the respective peak pressures and lowest areas.
For O-rings, flanges, etc., the CALTEST offers the possibility of evaluating the pressure curve along a circle line. To do this, define the starting point at any point, which is marked with a circle and no. 1. From there, the pressure curve is displayed clockwise. In addition to the quantitative representation of the pressure curve, the pressures can be precisely quantified at any 12 points.
In addition to many other applications, one should finally be mentioned, the freehand line. It is possible to cut out any areas of the impression, either to delete them or to evaluate only this area.
Technical Data CALTEST Program
Windows XP, 7, 8, 10
Stored calibration curves:
For all pressure measurement foils:
- Smooth surfaces
- Ambient temperature
- 40% and 60% humidity
- Contact time 60 s
Pressure measuring Fujifilm Prescale
Stored calibration curves are only valid for Tiedemann scanner
Included in the license agreement
Scope of delivery:
Program CD, A3 scanner, 2 licences, manual