Fischer FAQ

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.

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.

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.

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.

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.

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).

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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

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

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

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.

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)

For our tactile devices, you can find the latest version of our software in the media library.

When you purchase your FISCHER measuring device, you will receive all further information conveniently via a QR code.

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.

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.

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.

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

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.

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.

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

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

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.

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.

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.

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.

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).

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.

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.

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.

In measurement technology, normalization refers to the adjustment of the measurement task to the current settings or to new base materials. This must be carried out when changing the primary filter, the anode current, the collimator, or when using a new alloy of base materials. It ensures consistent and accurate measurement results.

Measuring equipment monitoring allows you to check whether your XRF device is functioning properly and to assess whether your measurement results genuinely reflect the sample or if a device defect is responsible. In measuring equipment monitoring, a specific reference sample (FISCHER standard or customer reference part) is measured at regular intervals under the same conditions. If the measurement falls within the tolerance and intervention limits previously set according to the application, it can be assumed that the XRF device is in proper working order.

The reference measurement is used to calibrate the energy axis. This can be done quickly and easily by the operator. The reference measurement is particularly valuable for XRF devices with proportional counters, for which reference measurements are recommended at regular intervals. It corrects XRF devices with proportional counters for temperature influences.

Calibration standards can be measured in the WinFTM® software under the menu item “Items ► Calibration Standards”. This ensures that the previous calibration is correct, that the device is still in perfect condition, or that recalibration is necessary. 

The recertification intervals depend on usage and can be determined by the user. Intervals of approximately 1 to 3 years are common to ensure high measurement accuracy.

In principle, Fischer calibration foils can be stacked. As a rule of thumb, 2 - 3 foils can be used for proportional counter devices and 1 foil for measuring devices with PIN or silicon drift detectors.

No, that is not necessary. The pure element plate contains pure elements for XRF saturation thickness, which remain stable when used with care and can be used for very long periods of time.
The only thing to avoid is mechanical damage and contamination.

The WinFTM® software allows the measurement of sample systems that are similar in base material compositions but still exhibit significant differences. This is often the case with copper alloys, for example. In such cases, the standardization or calibration process will ask for the base material calibration set and the base material of the object being measured. The former refers to the base material whose composition is known and is used for further calibration, while the latter refers to the base material of the customer part being measured. Care must be taken to avoid confusion here, as otherwise a systematic error will be calibrated.

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

Calibration standards are materials with a known and verified composition that are used to adjust and check XRF devices. They ensure that measurement results are accurate and reproducible.

The calibration standard should be as similar as possible to the material to be measured and the coating composition. This ensures that the calibration delivers realistic and accurate results.

FISCHER offers a very extensive range of over 500 certified standards. These include

• Solid standards for single and multiple layers, alloy layers, pure elements, and alloys

• Film standards for single and multiple layers and alloy layers, or prefabricated sets for specific industries and applications.

• Globally recognized traceability

• Over 500 certified standards

• Highest accuracy thanks to DAkkS certification, Link: www.helmut-fischer.com/why-fischer/dakks-calibration-laboratory

• Own accredited calibration laboratories worldwide

• Individual customer standards possible

• Comprehensive expert advice

We at Fischer do not specify a particular maintenance interval. The need to send in your standards for recalibration can be significantly influenced by usage conditions, environmental and storage factors, as well as your company’s reliance on specific standards and/or internal inspection equipment requirements. Therefore, you or your inspection equipment monitoring team are best positioned to assess and determine the appropriate interval for sending in your standards. A typical value would be approximately every 1–3 years.

Do you need individual consultation? Don’t hesitate to get in touch with us.

No, the certificate does not have a fixed expiration date. The need to send in your standards for recalibration can be significantly influenced by usage conditions, environmental and storage factors, as well as your company’s reliance on specific standards and/or internal inspection equipment requirements. Therefore, you or your inspection equipment monitoring team are best positioned to assess and determine when recalibration is necessary.

Do you need individual consultation? Don’t hesitate to get in touch with us.

Yes, we offer customized special solutions. On the one hand, we can combine layer thicknesses from our catalog to match your specific requirements, provided this is technically feasible. On the other hand, if technically possible, we can create a standard from your own material. Please feel free to discuss your needs with your personal Fischer representative.

Standards should never be cleaned mechanically or chemically! Doing so can cause damage, inhomogeneities, and/or a reduction in layer thickness, which may alter your calibration results.

Discoloration of Al, Cu, Ag: For these metals, oxidation of the metal surface forms an oxide layer that shields the underlying metal from further reaction with oxygen (passivation). Depending on the metal, this can cause typical discoloration, which, however, does not negatively affect the measurement results.

Important: Do not clean your standards! Removing the oxide layer by abrasion can lead to distorted calibration results.

Discoloration of Fe, Zn, Zn/Fe: In the case of iron oxidation (rust) or zinc oxidation (white rust), corrosion has a destructive effect on the standard. If corrosion occurs, these standards must be sent in for replacement. Since a corrosive environment accelerates the corrosion process, please always pay particular attention to the correct handling and storage of your standards (see also the following question).

Exceptional case COULOSCOPE® standards: Our COULOSCOPE® standards are an exception when it comes to cleaning. They come with an “eraser” that allows you to reactivate the nickel oxide layer.

Do not store your standards in condensing or corrosive atmospheres. Excessive humidity can damage the layers.

No, please do not remove the DAkkS marks from the cases. The DAkkS certificate remains valid only in conjunction with the corresponding DAkkS marks on the cases.

Upon request, we can reissue DAkkS certificates. However, please note that this involves a long lead time and additional costs. For this, please contact your personal Fischer representative directly who will be happy to provide you with an individual offer.

Not yet, unfortunately, but we are working on it.

Here you can find the terms and conditions.

Yes, but this depends on the polycapillary optics installed in your device. Depending on the polycapillary optics, you can measure measuring spots in the range of approx. 10-50 µm. With these very small measuring spots, you can visualize localized inhomogeneities, such as “pin holes”, or thickness differences on surfaces with high roughness. Single-point measurements of our calibration standards can therefore (depending on the material) lead to larger measurement scatter or falsification of the calibration results. For standards measured with our FISCHERSCOPE® X-RAY XDV®-µ devices, you should therefore always use scan mode.

Since standards are individual and not subject to normalization, we cannot issue a declaration of conformity. In addition, we also provide standards for RoHS measurements and special coatings, some of which require the use of materials that are not RoHS compliant.

Our standards are subject to manufacturing-related variations of ±20 % of the specified coating thickness. This does not constitute a defect but is within the permissible tolerance range. We always provide you with standards that are as close as possible to the specified quotation value.

All measurement values are subject to a certain degree of variation. Therefore, the values stated in the certificate after recertification may differ from the labeled value, as long as they remain within the specified measurement uncertainty. For tactile foils certified according to DIN EN ISO/IEC 17025:2017, the values printed on the foil may also differ from those listed in the certificate due to system-related factors. The current valid value is always the one stated in the certificate.

Yes, tactile standards are generally subject to natural wear and tear due to tactile measurement. As soon as damage such as dents or cracks become visible within the marked measuring surface, we recommend replacing the standard.

Foils for tactile measuring devices are subject to wear and tear due to use and therefore cannot be recertified.

The deviation in foil thickness is probably due to the measurement setup. We assume that the foils were measured with a flat stamp. With this method, virtually no impression is made in the foil when measuring the foil thickness. Thus, the actual thickness of the foil is measured. The foil thickness measured using this method is usually slightly higher than the foil thickness specified by Fischer.

The calibration foils measured by us are used to calibrate our devices with the corresponding measuring probes.

The measuring probes of Fischer have a small ball tip that is placed on the calibration foil or on the surface to be measured. When the probe is placed on the plastic foil, this ball tip creates a small pressure mark, which depends, among other things, on the thickness of the calibration foil. This indentation is taken into account when measuring our calibration foils. Consequently, the nominal value of the calibration foils manufactured by Helmut Fischer will always be slightly lower than the actual thickness of the calibration foil. If this pressure mark on the calibration foils were not taken into account, you would actually measure incorrect layer thicknesses on the real parts after calibrating our measuring devices with these foils.