ElektroPhysik MiniTest 725, MiniTest 745, MiniTest 735 Technical Manual And Operating Instructions

ElektroPhysik

Technical Manual / Operating Instructions

Coating Thickness Gauges

MiniTest 725, 735, 745

ElektroPhysik

Dr. Steingroever GmbH & Co. KG

Pasteurstr. 15

50735 Köln

Deutschland

Tel.: +49 221 752040

Fax.: +49 221 7520467

Internet: http://www.elektrophysik.com/

Mail:: info@elektrophysik.com © ElektroPhysik Version 1.0 01.08.2015 Gauge version: 2.1 Sensor software 1.1 Subject to change without notice

Table of contents

1. Introduction ............................................................................................................................... 6

2. First Steps ................................................................................................................................. 8

2.1 Insert batteries and connect sensor .................................................................................. 8

2.2 Switch-ON and take readings ............................................................................................. 9

3. Description of the Measuring System ................................................................................... 11

3.1 Gauge ................................................................................................................................. 11

3.1.1 General ....................................................................................................................... 11

3.1.2 Operating keys ............................................................................................................ 11

3.1.3 Infrared port ................................................................................................................ 12

3.1.4 Power Supply .............................................................................................................. 12

3.1.4.1 Batteries and Rechargeable batteries ...................................................................... 12

3.2 Sensors .............................................................................................................................. 14

3.2.1 SIDSP® technology ..................................................................................................... 14

3.2.2 MiniTest 745 Sensors ................................................................................................. 14

4. User Interface .......................................................................................................................... 15

4.1 Switch-ON and Start screen ............................................................................................. 15

4.2 Measure Mode Screen ...................................................................................................... 15

4.2.1 Online Statistics .......................................................................................................... 16

4.4 Menus................................................................................................................................. 16

4.4.1 Setting predefined parameters ...................................................................................... 17

4.4.2 Setting Numerical Parameters ....................................................................................... 17

5. Measuring ................................................................................................................................ 18

5.1 Important Notes on Coating Thickness Measurement ................................................... 18

5.1.1 Interpretation of readings ............................................................................................ 18

5.2 Necessary Settings ........................................................................................................... 18

5.2.1 Batch .......................................................................................................................... 18

5.3 Preparing Measurement.................................................................................................... 19

5.4 Taking readings ................................................................................................................. 19

5.4.1 Taking readings without using the sensor stand .......................................................... 19

5.4.2 High-precision stand ................................................................................................... 20

5.4.3 Duplex coatings systems ............................................................................................ 20

5.5 Errors during measurement ............................................................................................. 20

5.6 Measurement on hot surfaces (HT mode) with high-temperature sensors up to 350°C

(HT-mode) ................................................................................................................................ 21

6. Calibration ............................................................................................................................... 22

6.1 General remarks ................................................................................................................ 22

6.2 Calibration methods .......................................................................................................... 23

6.2.1 Factory calibration ....................................................................................................... 23

6.2.2 Manual calibration method .......................................................................................... 24

6.2.2.1 Zero calibration ........................................................................................................... 24

6.2.2.2 Two-point calibration .................................................................................................. 24

6.2.2.3 Multi-point calibration ................................................................................................. 24

6.2.3 Defined, menu-guided calibration methods ................................................................. 25

6.3 Blasted and rough surfaces ............................................................................................. 28

6.3.1 General remarks ............................................................................................................. 28

6.3.2 Method A (Roughness Rz > 20µm) ............................................................................. 29

6.3.3 Method B (Roughness Rz < 20µm) ............................................................................. 29

6.3.4 Method C ........................................................................................................................ 29

6.4 How to calibrate ................................................................................................................ 30

6.4.1 General remarks ......................................................................................................... 30

6.4.2 Factory calibration (STD) ............................................................................................ 30

6.4.3 Manual calibration ....................................................................................................... 31

Table of contents

6.5 How to recalibrate ............................................................................................................... 35

6.6 Interrupt or abort a calibration procedure ............................................................................. 35

6.7 Delete a calibration point ..................................................................................................... 36

6.8 Calibration – Quick reference ........................................................................................... 38

7. Data Management ................................................................................................................... 39

7.1 Batches .................................................................................................................................. 39

7.1.1 General remarks ......................................................................................................... 39

7.1.2 Memory Size ............................................................................................................... 39

7.1.3 Parameters ................................................................................................................. 39

7.2 Data base ........................................................................................................................... 40

7.2.1 General remarks ......................................................................................................... 40

7.2.2 Create a new batch ..................................................................................................... 40

7.2.3 Select a batch for taking readings ............................................................................... 44

7.2.4 Change a batch ........................................................................................................... 44

7.2.5 Parameter Overview ................................................................................................... 46

Parameters – List of symbols and their meanings ..................................................................... 46

7.2.6 Delete a batch ............................................................................................................. 47

8. Statistics / Statistical Evaluation ........................................................................................... 48

8.1 General remarks ................................................................................................................. 48

8.2 View statistics...................................................................................................................... 48

8.2.1 View statistics with disabled block option ......................................................................... 48

8.2.2 View single readings ........................................................................................................ 48

8.2.3 View statistics if readings are grouped into blocks ............................................................ 49

8.2.4 View single readings and block statistics .......................................................................... 49

8.3 Statistical values / Print-out and data transfer to a PC ......................................................... 50

8.4 Delete readings of a batch................................................................................................... 51

8.5 Delete a current reading ...................................................................................................... 51

9. Main menu ............................................................................................................................... 51

9.1 General remarks ................................................................................................................. 51

9.2 Data base ............................................................................................................................ 52

9.3 Display ................................................................................................................................ 52

9.4 SIDSP ............................................................................................................................... 54

9.5 Time / Date ......................................................................................................................... 54

9.6 Language ............................................................................................................................ 55

9.7 Measuring unit ..................................................................................................................... 55

9.8 Switch off mode ................................................................................................................... 55

9.9 Signal light .......................................................................................................................... 56

9.10 Signal tone ........................................................................................................................ 56

9.11 Sensor data ....................................................................................................................... 56

9.12 Gauge data ....................................................................................................................... 56

10. Additional Functions ............................................................................................................ 57

10.1 Initializing .......................................................................................................................... 59

10.2 Special functions ............................................................................................................... 61

10.3 Readjusting the factory zero-point ..................................................................................... 62

11. Quick reference ..................................................................................................................... 64

11.1 Synopsis ........................................................................................................................... 64

11.2 How to create a Batch ....................................................................................................... 65

12. Care and Maintenance .......................................................................................................... 66

12. 1 Care ................................................................................................................................. 66

12.1.1 Using NiMH rechargeable batteries ........................................................................... 66

12.2 Maintenance...................................................................................................................... 66

13. Technical Data ....................................................................................................................... 67

13.1 Gauge specifications ......................................................................................................... 67

13.2 Sensor specifications ..................................................................................................... 69

13.3 Delivery schedule ............................................................................................................ 71

13.3.1 MiniTest 725 with built-in SIDSP sensor .................................................................. 71

Table of contents

13.3.2 MiniTest 735 with external SIDSPsensor ................................................................. 72

13.3.3 MiniTest 745 with convertible SIDSP sensor ........................................................... 73

13.3.4 Convertible SIDSPsensors for MiniTest 745 ............................................................ 73

13.4 Accessories ..................................................................................................................... 74

14. Annexe ................................................................................................................................... 75

14.1 Error messages and remedy .......................................................................................... 75

14.2 Statistical Terms ............................................................................................................. 81

14.3 Safety Notes .................................................................................................................... 82

14.4 Declaration of Conformity .............................................................................................. 83

14.5 After Sales Service .......................................................................................................... 84

15. Change history ...................................................................................................................... 84

16. Index ...................................................................................................................................... 85

1. Introduction

Designed for non-destructive coating thickness measurement, the models of the MiniTest 700

series may be connected to different sensors. According to sensor, they work on the magnetic

induction principle or on the eddy currents principle. All models of the MiniTest 700 series conform

to the following industrial norms and standards:

DIN EN ISO 1461 DIN EN ISO 2064

DIN EN ISO 2178 DIN EN ISO 2360 DIN EN ISO 2808 DIN EN ISO 19840

ASTM B244 ASTM B499 ASTM D7091

ASTM E376-03

AS 3894.3-2002 SS 18 41 60 SSPC-PA 2

The portable gauges are suitable for non-destructive, quick and precise coating thickness

measurement. Easy to handle, they are the ideal tool for consumers, experts or public authorities

in the finishing industry, in paint shops, in the electroplating, ship and bridge building, aircraft

construction, engineering or chemical industry.

The measuring system comprises a sensor and a display unit. According to model, the gauge

features a built-in sensor, an external sensor or a convertible sensor.

Three basic models are available:

MiniTest 725 with a firmly connected built-in sensor

MiniTest 735 with a firmly connected external sensor

MiniTest 745 with a convertible sensor (can be changed from built-in to external on a lead). All

sensors of the MiniTest 700 series may be connected to this model.

According to sensor type, the gauges are suitable for the following substrate/coating combinations:

The F sensors work on the magnetic-induction principle and are suitable for measuring non-

magnetic coatings such as paint, enamel, rubber, aluminium, chrome, cupper, tin etc. on ferrous

bases and steel (also on alloyed steel or on hardened magnetic steel, but not on austenitic steel or

weak magnetic steel).

The N sensors work on the eddy currents principle and are suitable to measure insulating coatings

such as paint, anodising, ceramics, etc. on all kinds of non-ferrous metals such as aluminium,

cupper, zinc die casting, brass etc. as well as on austenitic steel.

The FN sensors work on both, on the magnetic-induction principle as well as on the eddy currents

principle. These sensors can be used for measurement on steel as well as on non-ferrous metal

substrates.

For printing out readings and statistics a portable printer MiniPrint 7000 is available as an option.

All models of the MiniTest 7X5 series are equipped with a USB interface and a Bluetooth interface

to enable data communication to a PC or the MiniPrint 7000 data printer.

For documentation of readings and statistics, all models of the 7X5 series are equipped with a USB

and Bluetooth interface to enable data communication to a PC or to a portable printer MiniPrint

7000 BT (available as an option). For data evaluation, a free of charge software MSoft 7 Basic

Edition is available. In addition, a more extensive software is available, MSoft 7 Professional

Edition (licence required).

2. First Steps

This section refers to persons to use the gauge for the first time. This section explains the main

features of the gauge and how to take readings.

2.1 Insert batteries and connect sensor

a) Take gauge and batteries from the case.

b) Loosen the screw of the battery compartment on the back-side of gauge and open the battery

compartment lid (e.g. by using a coin).

c) Insert the batteries supplied with the gauge into the battery compartment. Respect polarities

(as shown below).

d) Close lid and fix screw of battery compartment lid.

e) Above the battery compartment screw, a connection for fixing the hand-strap is located. The

hand-strap comes with the gauge and can be fixed now.

If you have purchased the MiniTest 725 or 735 model, please jump step f).

The MiniTest 745 model can be used with both, built-in and external sensor. The gauge comes

with the adapter cable fixed to the gauge for use with the external sensor.

For using the MiniTest 745 with external sensor, fix the sensor to the adapter cable. The

MiniTest 745 sensors come with two different types of measuring prisms: one with a small

contact surface for measuring small or curved parts, the second prism with a large contact

surface for large and even surfaces. The large prism serves also for fixing the sensor to the

MiniTest 745.

connection for hand strap

Use of MiniTest 745 with the external sensor

Connect sensor to adapter cable and screw in tight. The MiniTest 745 sensors come with

two prisms each, one for small curve radii and one for large radii and large surfaces. Select

a suitable prism according to your setting of task and fix it to the sensor.

Use of MiniTest 745 with built-in sensor

Turn coupling ring to remove it from the gauge. Remove adapter cable. Fix the large prism

to the sensor. Insert it into the gauge. Use coupling ring to screw in tight. The sensor can be

mounted to the gauge housing at any angle. Adjust the prism as requested for your setting

of task and fix firmly.

2.2 Switch-ON and take readings

Please note: The following steps to perform the initialising sequence need only be performed at

initial use.

1. The gauge must be switched OFF.

2. Press ON/OFF button on the left side of gauge and ESC key simultaneously.

3. Release ON/OFF button first.

The initialising sequence consisting of the following four steps will be launched:

Language

English (factory setting) appears.

Use arrow up/down keys to adjust to the requested language.

Press OK to confirm or ESC to abort and to go back to the previous setting.

If you abort, the factory setting (English) remains.

coupling ring

prism for large curve radii and large surfaces

prism for small curve radii

Total Reset Press OK to confirm.

IrDA- Port (cont. active) Press OK to confirm “cont. active”

Power supply (Battery) Press OK to confirm.

For more detailed information on the initialising sequence please refer to section 10.1.

The Start screen appears showing gauge model and sensor type being

connected (see fig. on the left)

With the FN sensors, the measuring method can be selected:

Press arrow up key for “Ferrous” (F for magnetic induction method)

Press arrow down key for “Non-ferrous” (N = eddy currents method).

Press OK to confirm your selection.

If you make no selection at all, the Auto F/N method will be automatically

adjusted after 5 seconds (see fig. on the left).

a) Now the gauge is in the measure mode and ready for measurement. The measure screen

appears (see fig. below). Readings are not yet available.

b) At initial use, “Batch 00” (see section 7.2.2) and the factory pre-setting (“STD”) are active.

For further information on “Calibration”, please refer to section 6. The active batch and the

calibration mode are shown in the status line.

c) The factory pre-setting is recommended for quick and easy measurement and if a medium

measuring accuracy is sufficient. For more details on calibration methods please refer to

section 6.2.

d) To take readings, place the sensor in right angle onto the measuring object. The coating

thickness will be immediately displayed on the screen. Remove sensor and take next

reading.

Status line

Set calibration method

Active Batch

Battery

state

Active measuring pro

ce-

dure, here: Auto F/N

Time

Online statistics

Bluetooth active

3. Description of the Measuring System

3.1 Gauge

3.1.1 General

Graphics display

128 x 64 dots

LED, green to confirm

acquisition of readings,

red to indicate if limits

have been exceeded

Large backlit graphics display for convenient

reading of readings and statistical values.

The gauge is equipped with a sturdy, scratch-

resistant plastics housing.

3.1.2 Operating keys

ON / OFF

button

Command and

navigation block

Function keys

Press ON/OFF button to switch the gauge ON or OFF. If you press ON/OFF button and ESC

simultaneously, the initializing procedure will be performed (for more details please refer to section

10.1).

Press Function key CAL to start the calibration procedure.

Press Function key MENU to call the main menu.

Press Function key STAT to call the statistics menu.

The command and navigation key block has the following functions:

Press OK to confirm settings or select menu items.

Press ESC to abort actions, to quit submenus or to navigate through a batch.

Use ARROW up/down keys to navigate through a menu or to change settings.

ESC and OK keys assume various functions according to menu being active

The navigation block symbol indicates the function of keys they

currently assume.

ESC and OK may assume different functions depending on the

menu being active.

So ESC may assume delete function (CLR) and OK may assume “>”

function for “next step”.

3.1.3 Interfaces

Please refer to sections 8.2 and 10.1

3.1.4 Power Supply

3.1.4.1 Batteries and Rechargeable batteries

All models, MiniTest 725, 735 and 745 are powered by a set of two alkaline-manganese cells,

1.5V, AA LR6 size (batteries are included in the standard supply schedule).

As an alternative, all models may also be operated on rechargeable NiMH (type AA-HR6)

rechargeable batteries. Please use only products as recommended by ElektroPhysik (See section

13.3 Accessories).

If you are using the rechargeable batteries, the power source setting must be adjusted accordingly.

(See section 10.1). For charging the rechargeable batteries, an external charger unit (available as

an option) must be used.

For more details on battery use please refer to section 12.1.1.

Note:

 Remove batteries or rechargeable batteries from the instrument if not in use for extended

periods.

 The battery symbol indicates 5 different battery states.

Infrared port (IrDA)

 When reaching the lowest battery state, the message “Battery almost empty” appears. In

this state, voltage is insufficient for powering the display backlight. The message “Backlight

failure – replace battery” appears on display.

 If batteries are completely discharged, the message “Low battery” appears and the gauge

switches off.

 Insert fresh batteries within one minute immediately after removing the used ones. If you

wait for longer than one minute, the message “Check clock settings” will appear (see

section 9.4). However, readings and calibration values will remain in memory.

 For field use, replacement batteries should be always at hand.  Erratic readings due to low battery do not occur as the gauge switches off automatically or

does not switch on at all if batteries are too low.

 Used or defective batteries or rechargeable batteries may contain hazardous substances

and must be disposed of according to the legal provisions of your country.

3.2 Sensors

3.2.1 SIDSP® technology

SIDSP® is world-wide leading technology for coating thickness sensors developed by

ElektroPhysik. With this new technology, ElektroPhysik has set another new benchmark for

innovative coating thickness measurement.

SIDSP® stands for Sensor-Integrated-Digital-Signal-Processing – a technology where the signals

are completely processed into digital form inside the sensor.

Unlike conventional techniques, the SIDSP® sensors create and control the excitation signals for

the sensor head inside the sensor. The return signals are directly digitally converted and

processed at a 32 bits accuracy to give you the complete coating thickness value. For this

technique, highly sophisticated methods of digital signal processing are used. This enables to

achieve a signal quality and precision unmatched so far with analogue signal processing.

SIDSP® sensors display extremely high interference immunity.

Anything that has to do with measuring signals will be handled by SIDSP in direct proximity to the

sensor head. No more interference during data transmission of the measuring signals via asensor

cable– because with SIDSP there is no measuring signal transmission taking place via the senor

cable. The sensor cable only supplies power to the sensor and serves as a communication

interface transmitting the coating thickness values to the display unit - in digital form.

All sensors feature an extremely wear-resistant sensor tip being most suitable also for hard coating

materials.

3.2.2 MiniTest 745 Sensors

For this model, a range of convertible sensors is available to cover the different measuring ranges

and applications. See also section 13.2.4 further details.

4. User Interface

4.1 Switch-ON and Start screen

At switch-on, the start screen appears showing gauge version and

sensor version being connected.

Approximately 2 seconds after switch-on, the gauges switches to the measuring mode of the last-

activated batch.

If an FN sensor is connected and if no readings have been taken so far, you can choose the

measuring principle via the keyboard.

Press arrow up key for Ferrous (F) (magnetic induction method).

Press arrow down key for non-ferrous (N) substrates (eddy currents method).

If you press OK, the Auto F/N mode (with automatic substrate identification) will be activated.

If you make no selection at all, the Auto F/N mode will be adjusted automatically after

approximately 5 seconds. In the Auto F/N mode, the gauge automatically identifies the substrate

material to adjust to a suitable measuring principle (magnetic induction or eddy currents).

4.2 Measure Mode Screen

Battery indicator

Calibration method

Active Status line

Maximum reading

Active measuring

method

Time clock

Number of readings

Standard deviation

Current reading

Average

Miniumum reading

Measuring unit

4.2.1 Online Statistics

During acquisition of readings, the measuring screen shows the current statistics of the active

batch in a separate window.

4.2.2 Rotatable Display

In the measuring mode you can rotate the display by 180°.

Press the arrow up/down keys to rotate.

4.4 Menus

The numerous MiniTest features can be accessed via the hierarchic structure of the main menu.

The main menu is subdivided into three submenus: “CAL” (calibration menu), “Menu” (main menu)

and “STAT” (statistics menu). These menus can be accessed via the CAL, Menu and STAT keys.

Press the Function key Menu to access the main menu.

Use arrow keys to select an item from the menu, e g. „SIDSP“.

Press OK to confirm your selection.

A submenu will open or a function will be called. (e. g. “Print”).

To go back to the previous menu level press ESC.

The parameter and data grouped as grouped under the various menus and submenus may be

divided into three categories:

predefined parameters that may be selected from a list

numerical parameters that may be adjusted within predefined limits

fixed parameters that may only be viewed but not changed

4.4.1 Setting predefined parameters

Use arrow up / down keys to scroll through the list of options of the

main menu.

Press OK to confirm you selection, e.g. “Language”.

Press OK to confirm.

Use arrow up / down keys to select a language.

Press OK to confirm. Your selection has been enabled.

To abort, press ESC before confirming your selection.

You will go back to the language selection level.

4.4.2 Setting Numerical Parameters

Numerical parameters can be changed within their predefined ranges.

Use arrow up / down key to change as requested.

If there is no predefined value available (display will show „---.--"), press

arrow up key to show the maximum value and arrow down key to show

the minimum value.

A brief pressing of arrow up / down keys will change the value to the

next increment. Pressing arrow keys continuously will increase the

setting speed accordingly (as with the repeat functions of PCs).

Press OK to confirm your setting or ESC to abort and to return to the

previous menu.

5. Measuring

5.1 Important Notes on Coating Thickness Measurement

Make sure the operator has been properly instructed regarding the use of coating thickness

gauges and has basic knowledge of the specific requirements for measurement of the application.

The operator should have basic knowledge of the following:

 Appropriate selection of a measuring device suitable for his application  Fundamentals on the electro-magnetic measuring principle  Influences trough magnetic fields and the surrounding fields  Influence through the surface properties of the object to be tested (roughness, shape and

build-ups on the surface)

 Statistical evaluation of measuring series

5.1.1 Interpretation of readings

The information obtained from the coating thickness measurement only refers to those parts of the

test object that have been covered by the sensor. For that reason, conclusions may not be drawn

on parts of the measuring object that have not been covered by the sensor during measurement. In

general, such conclusions are only admissible if comprehensive experience and approved

methods of statistical data acquisition are available.

5.2 Necessary Settings

Before taking readings, it is necessary to make a few settings in the “Data base” menu and the

“Batch” submenu.

5.2.1 Batch

With the MiniTest 700 series, readings are basically grouped into batches. A reading that has been

taken will be listed and stored into the currently active batch. After a switch-off, the gauge will recall

the last used batch so that you can conveniently continue to take readings in the last batch.

You can choose from the following batch actions:

Continue to take readings in the active batch

Create a new batch in the data base (see section 7.2.2)

Select an existing batch form the data base (see section 7.2.3)

5.3 Preparing Measurement

5.3.1 Calibration

According to your setting of task, you may use different calibration methods. Measuring accuracy

depends on the selected calibration method. Please refer to section 6.2 for more details on this

issue.

The following calibration methods are available:

Factory pre-setting

Manual calibration

o Zero calibration

o Two-point calibration

o Multi-point calibration

Pre-set calibrations „SSPC-PA2“, „Australian“, „Swedish“, „ISO“ and „Rough”

5.4 Taking Readings

5.4.1 Taking readings without using the sensor stand

All sensor systems are spring-mounted to ensure a safe contact pressure on the measuring object

without tilting. The V-groove of the sensor ensures correct positioning of the sensor on cylindrical

objects.

To take readings, place the external sensor of the MiniTest 735 or 745 model and/or, with the built-

in sensor, the complete gauge (MiniTest 725 or 745) onto the object to be measured. As soon as

the sensor has been placed onto the object, a reading will be displayed.

In the “Single readings mode”, the reading will be stored into the active batch. Lift the sensor briefly

and take the next reading.

In the „Scan mode“, readings are displayed continuously as long as the sensor is being placed on

the object. To store the single reading being displayed into the active batch, press OK key.

Please avoid scratching the sensor over the object to be measured in order to prevent wear-and-

tear of the sensor pole.

5.4.2 High-precision stand

For taking readings on small objects and small geometries, it is recommended to use the external

sensor in connection with the high-precision stand.

5.4.3 Duplex coating systems

To add additional corrosion protection to a product or for design reasons, it is common practice to

apply a zinc coating to a steel product before painting. For measurement of zinced steel with

additional surface finish, please use the dual sensors FN1.5 or FN5 sensors. With these sensors,

you can determine the thickness of the zinc coating as follows:

1. Set the gauge to ferrous substrates and take reading. The total thickness of zinc plus

surface finish will measured (thickness # 1)

2. Set the gauge to non-ferrous substrates. The zinc coating will be considered as non-ferrous

substrate and the thickness of paint will be measured (thickness # 2)

3. Now you can evaluate the thickness of zinc coating by calculating the difference between

the thickness #1 and thickness #2.

Please note that for measurement of duplex coating systems, a minimum zinc thickness of 50µm is

prerequisite. For checking whether your zinc coating thickness is sufficient, please take zero value

in the non-ferrous setting. Starting from a 50µm zinc thickness, the zero value is sufficiently good

so that you can measure your duplex coating as described above.

5.5 Errors during measurement

After the sensor has been calibrated, you can proceed on taking readings in the measuring mode.

Readings will be correct as long as the sensor specifications will be observed. Please refer also to

section 6.1 Calibration „General remarks“and Section 13 „Technical specifications“.

5.6 Measurement on hot surfaces (HT mode) with high-temperature sensors up to 350°C

(HT-mode)

The measuring system MiniTest 700 (gauge with sensor) is designed for a maximum operating

temperature of 60°C. Whilst the current operating temperature of the gauge depends on the

ambient temperature of the air, the current operating temperature of the sensor is also influenced

by the surface temperature of the object to be measured. This is due to the heat transfer taking

place when the sensors comes into contact with the object to be measured.

Measurements on objects with surface temperatures higher than the specified sensor operating

temperature are permissible with the special high-temperature sensors (such as item 80-173-5600

“F5 HT – 350°C”) under the following conditions:

1. When taking readings, a measuring signal will sound approx. 1 second after placing the

sensor onto the object to be measured in order to confirm acquisition of the reading. Make

sure to lift the sensor immediately after the bleep sounds. This is to keep the heat transfer

from the object to the sensor as low as possible. Do not keep the senor in contact with the

measuring object for longer than one second.

2. Note that between two subsequent measurements on hot surfaces, a recovery time is

required to cool down the sensor. Please refer to the table below for the temperature

depending recovery times. If the below recovery times are respected, a virtually unlimited

number of subsequent measurements can be taken.

3. During a measurement pause, make sure not to place the sensor on hot surfaces to

prevent heating up. Keep the sensor away from hot measuring objects to prevent heating

up through heat radiation.

Sensor recovery times in HT mode

Temperature

in °C

100°C 150°C 200°C 250°C 300°C 350°C

Recovery

time in

seconds

1 sec 2.5 sec 6 sec 12 sec 20 sec 30 sec

6. Calibration

6.1 General remarks

The MiniTest 700 series offers a number of calibration methods to meet the individual

requirements of various applications, procedures and industrial standards. If a batch is being

created you can select a suitable calibration method for this batch. The calibration can be carried

out immediately after you have created a batch or at a later time in the measuring mode. To call up

the calibration function in measure mode, press function key CAL. The calibration method can be

changed as long as no readings are stored in the currently active batch.

A calibration is made in the currently active batch and is directly related to this batch.

To ensure an optimum calibration, the following points should be observed:

 Correct calibration is vital for accurate measurement. For calibration, a sample similar to

the later object to be measured should be used, i.e. both, calibration sample and the object

to be measured should be of the same shape and geometry. As a rule, you can say that the

more similar the calibration sample and the later object to be measured are, the more

accurate calibration and thus accuracy of readings will be.

 Make sure the calibration sample and the later object to be measured have same

characteristics such as:

- identical curvature radius of surface

- identical substrate materials (such as magnetic permeability, electrical conductivity; in the

ideal case, they should be made of the same material)

- identical substrate thickness

- identical size of measuring area

 Before starting calibration, make sure the calibration spot, the sensor tip and the calibration

standard are clean. If necessary, remove any built-ups such as grease, metal chips, etc.

Any impurities might affect calibration and lead to erratic calibration.

 Make sure the calibration position and the measuring position are always the same, this

applies especially for measurement on small parts and measurements at edges and

corners.

 Keep away from strong magnetic fields during the calibration procedure.

 For maximum accuracy of calibration and later measurements, choose the thickness of

calibration standard within the same thickness range as the later measuring sample.

 For measuring thick non-ferrous metal coatings on steel or ferrous substrates according to

the magnetic induction method (with F1.5, FN1.5, F5, FN5 or F15 sensors), a multi-point

calibration must be carried out. The thickness standards must be of the same metal as the

later object to be measured.

 If using calibration foils, make sure they are placed in plane position on the substrate

material. Any air gap below the foils must be avoided as this would lead to erratic readings.

If the foils are curved, make sure to place on them on the substrate as shown below.

The precision thickness standards must be handled with care. Any wear-and tear of the thickness

standard will be reflected as erratic calibration value. Do not fold calibration foils. Any buckling will

cause air gaps below the foil and result in erratic readings. Keep thickness standard clean, free

from grease, oil, dust or other build-ups. Build-ups on the foils will be considered as thickness and

will lead to a measuring error of the same value as thickness of build-up. To give you a rough idea:

a build-up from a finger-print will be enough to add an additional thickness of some microns.

Please note:

If the gauge switches off during the calibration procedure due to low battery, the calibration

procedure must be repeated after batteries inserting fresh batteries.

6.2 Calibration methods

According to your setting of task, you may use different calibration methods. Measuring accuracy

depends on the selected calibration method. For more details please refer to section 13.2 Sensor

Specifications.

6.2.1 Factory pre-setting

The status line shows “Factory“ (“STD”)

The factory pre-setting is used for quick and easy measurement with a medium accuracy (for more

details please refer to section 13.2 Sensor Specifications). This calibration mode setting will be

valid as long as you do not choose and/or activate another calibration mode.

6.2.2 Manual calibration method

6.2.2.1 Zero calibration

”Z” is shown in the status line

calibration point: zero point (directly on the substrate material)

Calibration is to be made on an uncoated calibration sample of the same geometry and material as

the later measuring object. Only one calibration point is to be taken directly on the substrate to give

you the zero point.

Zero calibration is for quick calibration if a medium accuracy is sufficient.

6.2.2.2 Two-point calibration

”Z 1” is shown in the status line

Calibration points: zero point (directly on the substrate material) and on the precision standard.

Calibration is to be made on an uncoated calibration sample of the same geometry and material as

the later measuring object. Two calibration points are to be taken: one directly on the substrate to

give you the zero point, the other one on a precision standard which is put on the substrate.

Compared to the zero calibration, this calibration method implies a higher accuracy. Accuracy will

increase if the thickness of the precision standard is close to the thickness of the later object to be

measured.

6.2.2.3 Multi-point calibration

“Z 12” is shown in the status line.

Calibration points: zero point (directly on the substrate material) and on two precision standards.

Calibration is to be made on an uncoated calibration sample of the same geometry and material as

the later measuring object. Three calibration points are to be taken: one directly on the substrate to

give you the zero point, and two further ones on two precision standards to be put on the substrate.

It is recommended to choose a precision standard to cover the lower half of expected thickness

range, the other one should be in the higher half of expected thickness range.

This calibration method should be used if readings are to be taken over an extended thickness

range and if a high accuracy is required.

6.2.2.4 Two-point calibration without zero calibration

”12” is shown in the status line

calibration points: two precision standards (no zero point)

Calibration is to be made on an uncoated calibration sample of the same geometry and material as

the later measuring object. Two calibration points are to be taken on two precision standards which

are to be put on the substrate. The first precision standard should be thinner than the thickness to

be expected, the other one should be thicker than the thickness to be expected. There is no zero

point to be taken directly on the uncoated sample.

This specific calibration method should be used when taking readings on rough surfaces. Taking

zero point on rough surfaces would imply strong deviations due to the uneven surface. That’s why

zero point is omitted in this calibration method as this would lead to erratic calibration and thus

affect accuracy.

6.2.3 Defined, menu-guided calibration methods

6.2.3.1 General remarks

For all defined and menu-guided calibration methods the following applies:

The selection of a defined calibration method is made during the creation of a batch. After you

have completed the set-up of a batch, you may proceed on the menu-guided calibration. The

factory calibration will be valid until you have completed the calibration procedure. A running

calibration procedure is indicated by CAL flashing in the status line.

6.2.3.2 Calibration according to ISO (EN ISO 19840)

“ISO” is shown in the status line.

Calibration points: zero point (directly on the substrate material) and on two precision standards.

This standard does not apply if the target thickness is less than 40 microns.

Calibration is made on the uncoated calibration sample of the same geometry and substrate

material as the later object to be measured. Three calibration points are to be taken: zero point

(directly on the substrate) and two further one on two precision standards which are to be put on

the substrate. The first precision standard should be thinner than the thickness to be expected, the

other one should be thicker than the thickness to be expected.

To compensate for roughness, a correction value related to the actual roughness of sample must

be used according to the table below. As an alternative, a specific correction value can be

determined according to Method A (see section 6.3.2) and set accordingly.

If the roughness value is not known and no uncoated sample is available, the correction value “25

microns” should be used.

It is recommended to take sufficient readings according to the size of measuring area. A minimum

number of 5 readings should be taken.

The block statistics defines a number of 5 readings per block. If required, e. g. for larger surfaces,

you can increase the number of readings per block accordingly.

Roughness profile according to

ISO 8503-1

Correction value

(roughness) microns

fine 10

medium 25

coarse 40

6.2.3.3 Calibration method „rough“

“RGH” is shown in the status line.

Calibration points: on two precision standards (no zero point)

This calibration method is used for rough surfaces such as on blasted samples.

Two calibration points are to be taken on two precision standards which are to be put on the

substrate. The first precision standard should be thinner than the thickness to be expected, the

other one should be thicker than the thickness to be expected. There is no zero point to be taken

directly on the uncoated sample.

To achieve a maximum adaptation to the surface roughness of sample, you may use several

precision standards (50 µm max. thickness each) to lay them on top of each other. Thin precision

standards are more flexible than the thick ones and thus better adapt to uneven surfaces.

Take at least 5 to 10 readings to calculate the average thickness.

6.2.3.4 Calibration method “Swedish” (SS 18 41 60)

“SWD” is shown in the status line.

Calibration points: on two precision standards (no zero point)

Two calibration points are to be taken on two precision standards which are to be put on the

substrate. The first precision standard should be thinner than the thickness to be expected, the

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