Kistler 9240AA3 Owner's manual

Instruction

manual

9240A_002-763e-08.19

Quartz transverse

measuring pin

Type 9240A...

Type 9241C...

Instruction

manual

9240A_002-763e-08.19

Quartz transverse

measuring pin

Type 9240A...

Type 9241C...

Page 1

9240A_002-763e-08.19

The information in this manual is subject to change at any

time without prior notice. Kistler reserves the right to im-

prove and modify the product to reﬂect technical progress

without having to inform persons and organizations of

these changes.

protected by various intellectual property rights. For more

details visit www.kistler.com. The Kistler Group includes

Kistler Holding AG and all its subsidiaries in Europe, Asia,

the Americas and Australia.

Kistler Group

Eulachstrasse 22

8408 Winterthur

Switzerland

Tel. +41 52 224 11 11

info@kistler.com

www.kistler.com

Foreword

Quartz transverse measuring pin Type 9240A..., Type 9241C...

9240A_002-763e-08.19

Page 2

Content

1. Introduction .................................................................................................................................4

2. Important instructions ................................................................................................................5

2.1 For your safety ....................................................................................................................5

2.2 Unpacking ...........................................................................................................................5

2.3 Instructions on handling the device ....................................................................................6

2.4 Tips for using the Instruction manual ..................................................................................6

3. General device description ........................................................................................................7

3.1 What is extension? .............................................................................................................7

3.1.1 Longitudinal extension – transverse extension .....................................................7

3.2 What purpose does a strain sensor serve? .......................................................................8

3.3 Design and functional principle of strain sensor Types 9240A... and 9241C… ..................9

3.3.1 Design ...................................................................................................................9

3.3.2 Measuring principle ...............................................................................................9

3.4 Manufacturer's calibration of sensors ...............................................................................10

4. Installation and commissioning ..............................................................................................12

4.1 Important instructions .......................................................................................................12

4.2 Selecting the measuring point ..........................................................................................12

4.3 Structure materials ...........................................................................................................14

4.4 Consideration of thermal effects .......................................................................................14

4.5 Positioning the sensor ......................................................................................................14

4.5.1 Type 9240A…......................................................................................................14

4.5.2 Type 9241C… .....................................................................................................15

4.6 Installation ........................................................................................................................16

4.6.1 General installation instructions ..........................................................................16

4.6.2 Installation tool ....................................................................................................16

4.6.3 Installation instructions .......................................................................................17

4.6.4 Cable installation instructions ..............................................................................20

4.6.5 Cable concept .....................................................................................................21

4.7 Initial commissioning ........................................................................................................21

4.7.1 The simplest form of measurement – relative measurement ..............................22

4.7.2 The simplest form of measurement – extension .................................................22

4.7.3 Indirect force measurement.................................................................................24

5. Calibration ................................................................................................................................25

5.1 On-site calibration of a strain sensor ................................................................................25

5.1.1 Calibration of the operation point via a peak value comparison ..........................25

5.1.1.1 Test system requirements ....................................................................25

5.1.1.2 Installing the reference sensor .............................................................26

5.1.1.3 Procedure in the event of load application ...........................................26

5.1.1.4 Worksheet for the calibration process..................................................27

5.2 Kistler calibration service ..................................................................................................28

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9240A_002-763e-08.19

Total pages 48

6. Operation ...................................................................................................................................30

6.1 Quasistatic measurements ...............................................................................................30

6.2 Tips for good measurement values ..................................................................................30

7. Maintenance ..............................................................................................................................31

8. Eliminating malfunctions .........................................................................................................32

8.1 Troubleshooting and malfunction elimination ...................................................................32

8.2 Repairing the strain sensor ...............................................................................................32

8.3 Technical data ...................................................................................................................33

8.3.1 Strain sensor Type 9240A… ...............................................................................33

8.3.2 Strain sensor Type 9241C… ...............................................................................34

8.4 Dimensions of Type 9240A… ...........................................................................................34

8.5 Dimensions of Type 9241C… ...........................................................................................35

8.6 Connection variants ..........................................................................................................35

8.7 Ordering key .....................................................................................................................35

8.8 Optional accessories ........................................................................................................36

9. Appendix ....................................................................................................................................38

9.1 Glossary ...........................................................................................................................38

9.2 Measurement uncertainty .................................................................................................41

9.3 Linearity ............................................................................................................................42

9.4 Frequency range ..............................................................................................................44

9.5 Inuenceoftemperature ...................................................................................................45

Quartz transverse measuring pin Type 9240A..., Type 9241C...

9240A_002-763e-08.19

Page 4

1. Introduction

Thank you for choosing a Kistler quality product. Please

read this Instruction Manual carefully, so that you can

take optimum advantage of the versatile features of this

product.

Insofar as permitted under statute, Kistler refuses any

and all liability resulting from failure to observe this Instruc-

tion Manual or from the use of products other than

those listed under Accessories.

Kistler offers a wide range of measurement technology

products and complete solutions:

• Piezoelectric sensors for measuring pressure, power,

torque, extension, acceleration, shock, and vibration

• Strain gage sensor systems for measuring power and

torque

• Piezoresistive pressure sensors and transmitters with the

associated measuring ampliﬁers

• Associated measuring ampliﬁers (charge ampliﬁers,

piezoresistive ampliﬁers, etc.), indicators, and charge

calibrators

• Electronic control, monitoring, and evaluation units as

well as application-speciﬁc software for measurement

technology

• Data transmission modules (telemetry)

Kistler also designs complete measuring systems for spe-

cial-purpose

applications, e.g., in the automotive industry, in plastics

processing, and in the biomechanics sector.

Our General Catalog provides an overview of what we

offer. Detailed data sheets are available for practically

all of the products.

Should you have any speciﬁc questions after

reading these instructions, the global Kistler Customer Ser-

vice team is available to provide you with expert advice

on any application-speciﬁc problems.

Important instructions

Page 5

9240A_002-763e-08.19

2. Important instructions

Please observe the following instructions. Observing the

instructions is in the interest of your personal safety while

working and will ensure that the device continues to oper-

ate without any problems for a long period of time.

2.1 For your safety

• This device has been meticulously checked and left the

plant in an impeccable condition with respect to safety

considerations. To maintain this condition and ensure

hazard-free operation,

users must observe the instructions and warnings in this

Instruction Manual.

• The strain sensor may only be installed, operated,

and maintained by persons who are familiar with the

device and who are sufﬁciently qualiﬁed for their respec-

tive work.

• If it is to be assumed that hazard-free operation is no lon-

ger possible, then the device is to be put out of operation

and secured against being operated inadvertently.

It is to be assumed that hazard-free operation is no longer

possible:

• If the device exhibits visible damage

• If the device has been overloaded

• If the device no longer functions

• After prolonged storage under unfavorable conditions

• After signiﬁcant stress during transport

Attach the strain sensor in accordance with regulations.

For details on this, please refer to Chapter 4.

2.2 Unpacking

Check all of the device packaging for any transport dam-

age. Report any such damage to the transport company

and the responsible Kistler distributor.

Please check the included Accessories (see Chapter 1) be-

fore you start commissioning the device. If a part is miss-

ing, please contact the responsible Kistler distributor.

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Page 6

2.3 Instructions on handling the device

• Use the strain sensor only under the speciﬁed environ-

mental and operating conditions.

• Protect the connector of the strain sensor from con-

tamination and never touch the connector with your

ﬁngers (front of connector). Fit the cover supplied if

the connection is not occupied.

• Only use speciﬁed connecting cables.

• When not using the strain sensor, protect it by keeping it

in its original packaging.

2.4 Tips for using the Instruction manual

As a rule, we recommend that you read the entire Instruction

Manual. If, however, you are in a hurry and already have

experience with Kistler strain sensors, then you can limit your

reading to the information you currently require.

We have endeavored to structure these instructions in a

clear manner and thereby facilitate direct access

to the information you are looking for.

Please store this Instruction Manual in a safe place where it

always ready at hand.

If these instructions become lost, please contact your

Kistler

distributor and you will receive a replacement without

delay.

General device description

Page 7

9240A_002-763e-08.19

3. General device description

3.1 What is extension?

The physical measurand that is measured is the relative

extension ε and is deﬁned as the elongation of a machine

part under load divided by the original length l0.

If the dimensions of the object increase, reference is made to

a positive extension (or elongation); otherwise, reference is

made to a negative extension (or compression).

The measurand of ε is dimensionless. The SI unit for relative

extension ε is [m/m].

Kistler uses με as the unit for relative extension

1 με = 1 microstrain = 10–6 m/m = μm/m

3.1.1 Longitudinal extension – transverse extension

Each component that is extended or compressed in terms

of length undergoes a transverse extension in the trans-

verse direction. The transverse extension is usually around

30 % of the linear extension in the opposite direction. If

the component is compressed longitudinally, for example,

it elongates in the transverse direction. It can be possible

to utilize this effect depending on the application, with

the transverse extension measured instead of the linear

extension.

Fig. 1: Every object that is extended or compressed in a

given direction undergoes the opposite extension

in the transverse direction.













∆

=

−

=

m

l

ll µ

ε

00

01

Quartz transverse measuring pin Type 9240A..., Type 9241C...

9240A_002-763e-08.19

Page 8

3.2 What purpose does a strain sensor serve?

A strain sensor is primarily used to measure the extension

of a material within a structure. However, since the bearing

machine structure is subject to a more or less signiﬁcant ex-

tension or compression in the case of all processes in which

forces are applied, a strain sensor can be used just as well

for indirectly measuring dynamic and quasistatic forces

(see Fig. 2). The sensitivity of the indirect force measure-

ment must be determined using on-site system calibration.

Force shunt

Sensitivity

Direct force measurement undirect force measurement

Force shunt measurement

Fp = process force

Fs = force on the sensor

Fn = force on the structure,

force shunt

Fig. 2: The indirect force measurement based on the

extension forms one extreme in the spectrum

above. Despite low sensitivity, the relationship

between force and extension is in most cases

linear enough to allow measurements to be taken

and monitoring to be performed in a sufﬁciently

accurate manner.

The most important application areas for strain sensor

Types 9240A... and 9241C… are:

• Process monitoring of average forces

(press-ﬁtting, crimping, bonding, punching, precision

blanking, deep drawing, embossing)

• Process monitoring in presses that apply signiﬁcant

forces

(press forging, body pressing, etc.)

• Machine monitoring for machine tools

• Quality monitoring directly in the tool (punching, cold

massive forming, etc.) with compact Type 9240A

Range of the

indirect force

measurement

via the exten-

sion

General device description

Page 9

9240A_002-763e-08.19

Strain sensor Types 9240A... and 9241C… feature the

following excellent properties:

• Very good protection of the built-in sensor

• Long-term stability of the sensitivity level without

any signs of aging

• Durability when subjected to mechanical stress

• Miniaturized design

• High degree of ﬂexibility in terms of positioning within

the machine part

3.3 Design and functional principle of strain sensor Types 9240A...

and 9241C…

3.3.1 Design

Fig. 3: Schematic cross-section of strain sensor Type

9240A... / 9241C…

Strain sensor Type 9240A... and Type 9241C… primarily

consist of the following elements, which play an important

role in the equipment's function:

• Machine structure with 8 or 10 mm mounting bore,

which is cylindrically elongated or compressed.

• Piezoelectric measuring element (blue), which generates

a charge proportional to the deformation of the machine

structure by means of compression.

• Preload design consisting of preload cone, preload nut,

and threaded sleeve. Screwing the preload nut onto

the threaded sleeve pushes the sensor element into the

preload cone, thereby generating the desired preload

toward the outside.

8/10 mm

mounting bore

Preload cone

Sensor Preload nut Threaded sleeve Cable

Quartz transverse measuring pin Type 9240A..., Type 9241C...

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Page 10

3.3.2 Measuring principle

The deformation of the mounting bore caused by the

extension of the surrounding material results in a vertical

force being applied to the sensor element, in a similar way

to a conventional load washer. The alignment of the mea-

suring element can be varied prior to the preload by means

of turning so that the sensor can be precisely adapted to the

actual force ﬂux.

Alignment and preload are carried out with a specialized

installation tool (see 4.6 Installation).

Fig. 4: Typical characteristic curve of a strain sensor based

on conventional Kistler approach. This results in

negative sensor sensitivity S [pC/µε]

All Kistler force sensors are designed such that positive force

application generates a negative charge at the sensor out-

put. This corresponds to compressing the sensor and, there-

fore, compressing the surrounding material. By default, this

is converted into a positive output signal (voltage or current,

or digital value) by the connected charge ampliﬁer, based on

the conventional Kistler approach. In the case of elongation,

the plus/minus signs change accordingly.

General device description

Page 11

9240A_002-763e-08.19

3.4 Manufacturer's calibration of sensors

The transverse measuring pins are calibrated at the plant

where they were manufactured. During this, the actual

sensitivity [pC/µε] and the maximum linearity deviation

are determined using the process of 'continuous calibra-

tion'. The calibration is logged on the calibration certiﬁcate

supplied.

Calibrated ranges:

Measuring range

Type 9240A... 0–200 µε

Type 9241C… 0–200 µε

Fig. 5: Example of calibration certiﬁcate supplied; Type

9240A… (left) and Type 9241C… (right)

The calibration process is carried out using a model com-

pression body, making it possible to determine the resulting

extension due to the force applied at any time.

In the case of direct extension measurement, the result of

the manufacturer's calibration can be used. If the sen-

sor sensitivity and the charge ampliﬁcation are known, it

is possible to back-calculate the extension measured by

means of the voltage signal.

In all cases where an indirect force measurement is to be

performed using the strain sensors, on-site calibration must

be carried out (see Chapter 5.1).

Quartz transverse measuring pin Type 9240A..., Type 9241C...

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Page 12

4. Installation and commissioning

4.1 Important instructions

Strain sensor Type 9240A... and Type 9241C… are preci-

sion instruments; the features speciﬁed can only be fully

utilized if the sensors are used correctly and can only be

maintained if the sensors are handled with care. Please

observe the following instructions:

• Strain sensors may only be installed by persons who are

sufﬁciently qualiﬁed for this work.

• Do not allow strain sensors to fall and do not expose

them to severe impact. The peak force of this kind of

shock can cause lasting damage.

• Do not use a hammer to position the workpieces as

impact of this kind can also lead to damage.

You will ﬁnd instructions for installing the strain sensor and

setting up the measuring chain in the chapters below.

If anything is unclear or difﬁculties arise when installing the

strain sensors, please contact the responsible plant distribu-

tor for advice. In cases where it is necessary to contact the

customer service team, the user must adequately docu-

ment the measurement issue through drawings, descrip-

tions, and calculations.

4.2 Selecting the measuring point

To enable a successful indirect force measurement, particu-

lar attention must be paid to selecting the measuring point.

Requirements for the measuring chain:

• The extension at the measuring point should be as pro-

portional as possible to the force being measured.

• A machine that does not allow exact position ﬁxing

of the force application point must be equipped with

multiple strain sensors if the measurement always has

to correspond precisely to the working force irrespective

of the force application point (e.g., 2 or 4 sensors are

required for a 4-column press).

• On the one hand, the extensions at the measuring point

must be within the measuring range of the sensor. On

the other hand, however, it must be ensured that the

measuring range of the strain sensor is used as effective-

ly as possible to maintain the greatest possible interfer-

ence signal distance during operation.

Installation and commissioning

Page 13

9240A_002-763e-08.19

• The measuring point must not be exposed to high

thermal stress (thermal radiation and airﬂow). Ideally,

the material and ambient temperature at the measuring

point will be equal and consistent during the measuring

cycle.

• To keep the sensor dry, it must be ensured that the

mounting bore does not ﬁll up with liquid.

There is very little chance of ﬁnding machine measuring

points with extensions caused by tensile and compression

loads alone. At virtually every measuring point, there is

an extension resulting from a combination of tensile or

compression load and bending stress. The proportion of

the extension caused by bending is often signiﬁcantly

higher than that caused purely by tension or pressure. A

more precise examination of the link between extension

caused by bending and working force frequently indi-

cates nonlinear characteristics, the cause of which is to be

found in opening suspension effects of bearing and ﬂange

surfaces or in separation plane sliding effects. In the case

of extension measurement during working force calibra-

tion, nonlinearities of this kind become apparent when the

correlation between the reference force and the extension

signal is measured.

The proportion of bending stress and elongation in the

measurement can be inﬂuenced by the position of the

sensor within the machine component.

Fig. 6: Simultaneously occurring extension and compres-

sion on a bent object. The proportion of these

two force effects in the measurement result may

vary according to the horizontal positioning of

the transverse measuring pin.

Quartz transverse measuring pin Type 9240A..., Type 9241C...

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Page 14

4.3 Structure materials

As a rule, it is possible to use the equipment in steel

structures without any problems. Extension measurements

in other materials such as cast iron, aluminum, or other

metals must be undertaken with caution; in such cases,

the sensor must be re-calibrated. Known problems include

reduced surface pressure and, consequently, reduced

preload, hysteresis effects, as well as material fatigue in the

contact area.

4.4 Consideration of thermal effects

The preload and, to a limited extent, the sensitivity of the

sensor change as a result of temperature changes in the

structure. The change to the preload has a direct inﬂuence

on the measuring range that can be used and is highly

dependent on the material of the surrounding structure.

4.5 Positioning the sensor

4.5.1 Type 9240A…

Fig. 7: Hole-mounting, Type 9240A

In contrast to other strain sensors, the measuring point can

be varied slightly in the direction of the borehole by means

of a transverse measuring pin, enabling a greater degree

of ﬂexibility when selecting the measuring point. However,

the following points must be considered in the process:

Installation and commissioning

Page 15

9240A_002-763e-08.19

• The borehole must be clean and prepared with a toler-

ance of H8 over 8 mm

• A minimum installation depth of 8mm must be main-

tained

• In the event that the measuring pin is completely coun-

tersunk, the borehole must be sealed following installa-

tion with a Type 65000539 sealing plug

4.5.2 Type 9241C…

Fig. 8: Deep hole-mounting, Type 9240A

In contrast to other strain sensors, the measuring point can

be varied slightly in the direction of the borehole by means

of a transverse measuring pin, enabling a greater degree

of ﬂexibility when selecting the measuring point. However,

the following points must be considered in the process:

• The borehole must be clean and prepared with a toler-

ance of H8 over 10 mm

• A minimum installation depth of 10mm must be main-

tained

• In the event that the measuring pin is completely coun-

tersunk, the borehole must be sealed following installa-

tion with a Type 3,112,024 sealing plug

Quartz transverse measuring pin Type 9240A..., Type 9241C...

9240A_002-763e-08.19

Page 16

4.6 Installation

4.6.1 General installation instructions

Correct installation is important for ensuring quality – par-

ticularly when it comes to reproducibility.

• Carefully clean the mounting bore to be used with a

de-greasing cleaning agent (such as ethanol, acetone,

carbon tetrachloride, or benzine).

• The sensor must be aligned with the direction of the

greatest anticipated extension.

• Special installation tool Type 1393B… must be

used for installing sensor Type 9241C… and special tool

Type 1300A161A must be used for installing sensor Type

9240A....

• Before installation, the insulation must be checked with

an insulation testing device (Type 5493).

Before performing the measurement or calibration, the ma-

chine must be exposed to the maximum working force at

least ten times using installed and preloaded strain sensors.

4.6.2 Installation tool

Fig. 9: Design of the installation tool

The installation tool consists of 2 parts:

A – Positioning and preloading tool

This is the external part

B – Orientation tool

This is the internal part

C – The notch on the orientation tool indicates

the alignment of the sensor during the installation

process

Installation and commissioning

Page 17

9240A_002-763e-08.19

4.6.3 Installation instructions

Step 1:

Guide the connector and sensor cable through the preload-

ing tool (A) as shown

Fig. 10: Inserting the cable into the installation tool

Step 2:

Carefully pull the sensor cable completely through the tool

element (A) until the sensor is at the front end.

Never pull the sensor cable forcefully or in a jolting manner

as this may damage it.

Fig. 11: Pulling the sensor cable completely through

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