# Fischer FAQ

## Any questions?

There is a lot to tell, and you are sure to have questions, as well. Here are the most common ones. If you need more answers, just contact us. We will be glad to help you.

You will also find many interesting tutorials and other useful information in our media library.

• ### FAQ Important parameters

Mean value / Range / Standard deviation / Coefficient of variation

Mean value

The simplest way to calculate a mean value is to add up all values and divide this sum by the number of values. This is called the arithmetic mean. There are other ways to calculate a mean, but they are rarely used.

Range

The range R shows how far apart the smallest and the largest measured value are. To calculate the range, the lowest measured value is subtracted from the largest. The range can be strongly distorted by outliers and is therefore only useful if you have few measured values. For large amounts of data, the standard deviation is more meaningful.

Standard deviation

The standard deviation σ indicates how strongly the measured values scatter around the mean value. A high standard deviation indicates that the measured values differ greatly from one another. If the values are all close to the mean, the standard deviation is small. How well the mean and the standard deviation describe reality depends, among other things, on the number of measured values. The more measurement points, the more meaningful the ratios become.

Coefficient of variation

The size of the standard deviation depends not only on the dispersion of the measured values, but also on the magnitude of the values – a higher mean value quite automatically leads to a higher standard deviation. To deal with this problem, the relative standard deviation, the coefficient of variation V, is often expressed as a percentage. Here, the standard deviation is divided by the arithmetic mean. As with the standard deviation, high values here also indicate a high dispersion of the measured values.

• ### FAQ XRF

Application / Radiation protection / Software and others

What can be measured with the XRF method?

One can measure elements from atomic number 11, with layer thicknesses ranging from approx. 0.005 - 60 µm, depending on the ambient medium (air, helium, vacuum), the detector, the spot size, the atomic number and of course the application.

What is the measuring spot size for XRF measurements?

The measuring spot depends on the collimator and the measuring distance. Typical values are 30 µm to 3 mm.

How accurate are the measurement results of Fischer XRF instruments?

The measuring accuracy can be different for each measuring task. It depends on the measuring time, the measuring spot and the uncertainty of the standards with which the XRF instrument has been calibrated.

Radiation protection for Fischer XRF instruments?

The vast majority of our XRF instruments are type-approved full protection instruments according to the German Radiation Protection Ordinance.

What does the "Data export" mask mean?

The definition of the export mask can be used to determine which parameters are to be exported. The export setting defines when and where the data is sent. The measurement data is then available as a text file.

What is measured when the XRF device asks for "Scatt"?

Here a scatter spectrum is asked for. The scatter spectrum does not have to be measured, but can be loaded in the menu: General ► Load spectrum and evaluate...

Why can't I create new measuring tasks?

The super software is not enabled.

The XRF device prints out all measured values without being asked.

Presumably, Print single values has been activated in the File menu. In this case, each single value is sent to the printer buffer and, when a page is full, it is printed automatically. Deactivate "Print single values" and clear the printer buffer.

Measured values were deleted by mistake. Can I restore them?

If single values have been deleted within a block, a dash appears in the enumeration of the measured values. Such measured values can be made visible again in the Evaluation ► Restore measured value menu. However, if all measured values of a block or an item are deleted, it is not possible to restore the data.

• ### FAQ Tactile

Measuring method / Probes / Software and others

What factors play a role in the measuring accuracy of Fischer coating thickness gauges?

The measuring accuracy of coating thickness gauges depends on factors such as the coating thickness, surface condition, probe used, etc. Information on accuracy and repeatability under ideal conditions can be found in the technical data sheets of the probes.

Phase-sensitive eddy current method: Which layer-base material combinations can I measure?

There are various measurement options here: For example, I can use the phase-sensitive eddy current method to measure non-magnetizable metal on magnetizable metal. An example of this is zinc on iron. But non-magnetizable metal on electrically non-conductive plastic would also be conceivable, such as copper on Iso. Another measurement example is nickel on copper (magnetizable metal on non-magnetizable metal).

Amplitude-sensitive eddy current method: Which layer-base material combinations can I measure?

The amplitude-sensitive eddy current method is used to measure electrically non-conductive coatings on electrically conductive, non-magnetizable base materials, such as anodizing or paint on aluminum, paint on copper or ceramic on titanium.

Magnetic induction method: Which layer-base material combinations can I measure?

With the magnetic induction method, you measure non-magnetic coatings on base materials that are easy to magnetize, such as zinc on iron or paint on iron.

What do I have to consider when measuring nickel layers with phase-sensitive eddy current probes as well as magnetic inductive probes?

In each case, it must be calibrated with actual nickel-plated parts and their known coating thickness. The magnetism of nickel coatings can vary greatly, so it may be quite different on the parts to be measured than on the calibration parts. This can lead to measurement errors, which may be a problem – especially with incoming goods inspection.

An unknown error message is displayed by the measuring device or the Fischer program. How do I proceed?

First look in the operating instructions to see if the error and its correction are described therein. If not, please send us the serial number, the exact designation of the measuring device, the measuring probe, the version number of the Fischer program, the error number (error code), the exact wording of the error message and the circumstances that led to the error. Here you will find your contact persons.

Which method does the SIGMASCOPE® use to measure the specific electrical conductivity?

With the phase-sensitive eddy current method (see draft standard DIN 50994 and standard DIN EN 2004-1).

What does the unit of measurement MS/m mean for SIGMASCOPE®?

MS/m means Mega-Siemens per m, which corresponds to 1,000,000 Siemens/m. This unit is the reciprocal (inverse) of the unit of measurement for the specific electrical resistivity Ohm x mm²/m. 1 Siemens therefore corresponds to 1/Ohm.

What does the unit of measurement %IACS mean for SIGMASCOPE®?

IACS means "International Annealed Copper Standard". This unit of measurement is often used in Anglo-American countries. The following applies: The specific electrical conductivity of 100 %IACS corresponds to 58 MS/m. With this relationship, any value of electrical conductivity can be converted from one unit of measurement to the other.

Why do I have to pay attention to the temperature of the objects to be measured when measuring the electrical conductivity with the SIGMASCOPE®?

The specific electrical conductivity is directly dependent on the temperature. The higher the temperature, the lower the conductivity. To ensure that the measured values are comparable, conductivity is always specified with reference to 20°C. For this reason, the conductivity standards from Fischer also give values for 20°C.

For the SIGMASCOPE® to be able to convert a measured value of the physically real conductivity to 20°C, the following conditions must be met:

• Either the instrument must be calibrated at the same temperature that is present during the measuring.
• Or the temperature of the object to be measured must be recorded with a temperature sensor (internal/external) during measurement and calibration.

If these conditions are not met, systematic measurement errors may occur.

Which probes can be used to measure the coating thicknesses of duplex coating systems "paint on hot-dip zinc on steel" in heavy corrosion protection?

With the FDX10 and FDX13H duplex measuring probes. These probes require a minimum coating thickness for hot-dip zinc of 70 µm in order to measure correctly.

Which probes can be used to measure the coating thicknesses for the duplex coating system "paint on weakly galvanized steel"?

For thin zinc layers, the ESG2 and ESG20 probes are used. These probes can only be applied if there is no diffusion layer between zinc and steel. This is usually the case with electroplating and very thin hot-dip zinc coatings (such as in automotive engineering). Hot-dip zinc coatings in heavy corrosion protection, which are often more than 70 µm thick, usually form a distinct diffusion layer between steel and zinc. For such cases, the ESG2 and ESG20 probes cannot be used.

Which layer-base material combinations can be measured with the coulometric method?

Electrically conductive metal layers on metals, plastics or on ceramics. Learn more

What are the requirements for coulometric measuring?

The following must be fulfilled: a clean coating surface, good contact of the stand clamp to the object to be measured. Furthermore, one should select a detachment speed corresponding to the coating thickness. In addition, one must use the appropriate electrolyte. Learn more

What factors play a role in the accuracy of the coulometric measurement method?

The factors are: coating thickness, surface condition, the measuring cell seal used, detachment speed and the purity of the coating.

What do I have to do to transfer data to my computer?

Connect the transfer cable to the computer and the measuring device. Install the appropriate driver software on your computer. Select the correct interface to which an instrument is connected in the evaluation program you are using. To separate groups of measured values, please set a group separator in the measuring device.

Why does my data transmission not work?

The reason could be: Was the correct driver loaded with administrator rights? Was the correct interface selected in the software on the computer? (see furthermore Device Manager)

• ### FAQ Nanoindentation

Measuring / Measured values / Software and others

My readings vary greatly. What can be the reason for this?

The zero point cannot always be reliably determined for rough surfaces. Therefore, if possible, the surface should be polished. Air currents and external vibrations can also lead to high fluctuations in measured values or even to incorrect measurements. For this reason, the instruments should be set up in a protected location. When measuring with very low forces, closed measuring boxes and damping tables help to avoid external influences.

My measured values are wrong. What could be the reason for this?

Possibly the indentor is dirty or worn. The WIN-HCU® provides a cleaning procedure that should be performed regularly. Also check whether you have selected the correct force-time regime for your application. Different test parameters can lead to deviations.

If these measures do not help, a shape correction can also be performed if the indenter is worn. Shape correction should only be carried out by Fischer experts.

After measuring, no Indentor imprint can be seen on the surface. Why?

Possibly the wrong objective is set on the microscope. Try a different objective and make sure that you have selected the correct objective in the WIN-HCU® software for instruments without automatic objective recognition.

If the impression is still not visible, you may have selected too low an inspection force. In such cases, the impression can be seen with an atomic force microscope (AFM), for example. Another reason could be too large an offset between the microscope position and the actual measuring position. The set offset settings can be found under Measuring table ► Microscope settings.

When measuring coatings in cross-section, it is recommended to use an appropriate micro-section sample holder from Fischer. If measurements are performed on transverse sections without a suitable holder, there will be a systematic offset from the measuring position to the microscope position for each measurement due to the mounting process.

Why do I not get any measured values for indentation hardness and indentation modulus?

Probably the unloading curve was not recorded. Please check your settings. In addition, very soft samples can continue to deform under load (creep), which is why the indentation hardness cannot be determined in every case. Use the creep setting to determine the indentation creep (CIT). Use the Edit ► Application settings ► Parameters ► Straight, to determine indentation modulus EIT and indentation hardness HIT according to ISO 14577.

The sample has yielded under the load during measuring. Check whether the test specimen is well fixed. Depending on the component geometry, use our suitable accessories: the HM universal specimen grips or the HM foil clamping fixture from Fischer.

The loading curve has a kink. What could be the reason for this?

The selected test load is too high for the coating thickness. The substrate material thus influences the measuring.

Why can't I activate the "Dynamic measurement mode"?

You can only activate the dynamic measuring mode as an administrator. If activation is not possible despite administrator rights, this is usually due to customer-specific security-relevant software that prevents this. One possibility here is to use a computer with lower software-related security precautions.

Why is the menu item "Shape correction" grayed out and not selectable?

The shape correction requires administrator rights. Please log in to WIN-HCU® accordingly. Shape correction should only be performed by Fischer experts or qualified personnel. The measuring was aborted and no new measuring can be started. In addition, the indentor position is at a value above 400 µm.

Why do I get an error message when I click 'Evaluation' ► 'Custom export'?

You must first define the user-defined export under Setting ► Options ► User-defined export, before you can execute the export.

Where can I find the serial number and other important information about my measuring device?

Select ? ► Info about WIN-HCU. Here you will find, for example, the serial number of the measuring device and the version of WIN-HCU®.

• ### FAQ Calibration Tactile

Statistical parameters / Calibration check / Calibration of probes and others

Which statistical characteristic values should be used as a minimum when using measured values?

For the comparison of measured values, at least the following characteristic values should be used: Arithmetic mean, standard deviation and number of individual measured values. Without the corresponding standard deviation and number of measured values, mean values cannot be meaningfully and seriously compared with each other.

Why do I have to calibrate my measuring device?

According to the DIN EN ISO 9001 standard, measuring equipment must be calibrated if traceability is required. Every physical measuring method is influenced by the properties of the coating and base material. Examples of these properties are: part geometry, electrical conductivity, magnetism, density of the coating, or even the measuring surface. Therefore, every time the properties of the layer or base material change, it is most likely necessary to recalibrate the measuring equipment.

I calibrate my magnetic inductive or eddy current measuring device on a flat sheet and now want to measure on a turned part with a small diameter, for example. Is it possible to do this without another adjusted calibration?

No. Calibration on the flat sheet creates a systematic measurement error on the curved surface. As a result, the measured values will be too high. This is because the measuring device evaluates the signals from the curved object as if they were coming from a flat part. Therefore, regular calibrations are necessary when the shape or geometry of the parts or measuring surface changes.

Two people arrive at different measurement results. What could be the reason for this and what can be done about it?

Possible causes could be that two measuring devices with different calibrations (characteristic curves) are used or that measurements were made with the same measuring device but on different measuring surfaces. The correctness of measured values obtained with measuring devices is always ensured by calibration standards. In the case of magnetic induction and eddy current measuring devices, calibration must be performed on the measuring surface of the real, uncoated objects to be measured, on which the coating thickness must also be measured for the coated parts. Furthermore, it must be ensured that measurements are taken at the same point or on the same measuring surface and that a sufficient number of measured values are recorded for a meaningful mean value as well as a meaningful standard deviation. Only in this way can comparable measurement results be achieved.

How do you check a calibration for tactile coating thickness gauges?

One measures a calibration foil on the uncoated workpiece with several measured values (usually 5 to 10) and this at the point where measurements will be taken later. Fischer base calibration plates are not useful for this calibration. Subsequently, the user must decide which deviations from the film setpoint and the measured mean value he will allow, so that the measuring device is still considered to be sufficiently well calibrated. The assessment of the calibration of a measuring device in the context of statistics and with regard to the uncertainty of the measured film thickness is provided, for example, by the standards DIN EN ISO 2178: 2016 "Non-magnetic coatings on magnetic base metals – Measurement of film thickness – Magnetic method" (Chapter 8) and DIN EN ISO 2360:2017 "Non-conductive coatings on non-magnetic metallic base materials – Measurement of film thickness – Eddy current method" (Chapter 8).

What must be taken into account when calibrating the FDX10 and FDX13H duplex probes?

These duplex probes have two measuring channels. The magnetic inductive channel measures the total coating thickness of paint and zinc. The amplitude-sensitive eddy current channel measures the paint layer thickness on the zinc. For the calibration, a completely uncoated steel part corresponding to the original part and a galvanized part with at least 70 µm zinc are required. The magnetic inductive channel of the probes is calibrated on the uncoated steel part. The calibration foils used should frame the expected total coating thickness range (paint and zinc). The galvanized part is used to calibrate the amplitude sensitive eddy current channel. The calibration foils used should frame the expected paint layer thickness range.

What should be considered when calibrating the ESG2 and ESG20 duplex probes?

These duplex probes have two measuring channels. The magnetic inductive channel measures the total coating thickness of paint and zinc. The phase-sensitive eddy current channel measures the zinc coating thickness under the paint. For the calibration, a completely uncoated steel part corresponding to the original part and a galvanized part with a typical zinc coating are required. The magnetic inductive channel of the probes is calibrated on the uncoated steel part. The calibration foils used should frame the expected total coating thickness range (paint and zinc). On the galvanized part, the phase sensitive eddy current channel of the probes is calibrated. No calibration foils should be used here, as the zinc layer itself is the calibration layer. It is only necessary to measure on the galvanized part during this step of the calibration. The zinc layer thickness does not need to be measured as a reference layer thickness before calibration. The calibration reference value of the zinc layer is provided by the magnetic inductive channel calibrated in the first step.

Does the density of the coating play a role in calibration?

Yes, it does. For example, if the measuring device was calibrated with a part whose coating has a density of 2 g/cm³, and measurements are now to be taken on a part with a density of 1 g/cm³, for example, systematic measurement errors will occur. The measured values are then too low. This is the case because the measuring device evaluates the signals from the new object as if its layer also had the density 2 g/cm³.

• ### FAQ Calibration XRF devices

Checking the calibration / Calibration standards and others

What is meant by nomination in a Fischer XRF instrument?

In measurement technology, nomination is the adaptation of the measuring task to the current settings or to new base materials. This must be done when the primary filter, the anode current or the collimator are changed. It is also standard-required if the alloy composition of the base material has changed.

My Fischer XRF instrument measures implausible values. How can I be sure that I am still measuring correctly?

Here one goes the way of the measuring device monitoring. One checks the XRF measuring device by re-measuring calibration standards. The standard calls this "calibration". If there is a significant deviation between the measured value and the nominal value of the standards, an adjustment is necessary.

What is a reference measurement on a Fischer XRF instrument?

A reference measurement is a recalibration of the energy axis. It corrects XRF instruments with proportional counter tube for temperature influence.

How to check a calibration on the XRF instrument?

Calibration standards can be remeasured in the menu item Item ►Measure calibration standards. If a deviation is detected, the XRF instrument must be recalibrated.

How often should X-ray calibration standards be referenced?

This depends on how often the measuring devices are used to measure on the calibration standards. Therefore, this can be determined by the customer. A typical value would be approximately every 1-3 years.

Is it possible to stack the X-ray calibration foils during the calibration process?

Yes, this is possible. As a rule of thumb, 2-3 foils can be used for proportional counter tube measuring devices and 1 foil for measuring devices with PIN or silicon drift detectors.

Should I recertify the pure element plate for XRF instruments?

No, it is not necessary. You do not need to recertify the pure element plate because the standards have very high stability due to their saturation thickness.

What to do if the XRF instrument asks for "Base material cal. set" and "Base material measurement object" during nomination or calibration?

Here the WinFTM® asks for the base material. The uncoated base material of the calibration set and of the measured object must be applied and measured. Caution: If the wrong parts are placed here, this can have a very large influence on the correctness of the result.

What is the difference between a factory certificate and an ISO 17025 certificate for calibration standards?

Calibration standards with the ISO 17025 certificate are measured according to a procedure defined by the accreditation societies and have a lower uncertainty than calibration standards with a factory certificate.