Kistler 9001C Series User manual

Instruction
Manual
9001C_002-928e-12.20
Piezoelectric Force Sensors,
Ring Force Transducers
Types 9001C ... 9091C,
9101C ... 9107C,
9130C ... 9137C

Page 1
9001C_002-928e-12.20
Thank you for choosing a Kistler quality product charac-
terized by technical innovation, precision and long life.
Information in this document is subject to change without
notice. Kistler reserves the right to change or improve its
products and make changes in the content without
obligation to notify any person or organization of such
changes or improvements.
© 2020 Kistler Group. Kistler Group products are protected
by various intellectual property rights. For more details visit
www.kistler.com. The Kistler Group includes Kistler Hol-
ding AG and all its subsidiaries in Europe, Asia, the Ameri-
cas and Australia.
Kistler Group
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8408 Winterthur
Switzerland
Tel. [phone]
[e-mail]
www.kistler.com
Foreword
Foreword

Piezoelectric Force Sensors, Ring Force Transducers
9001C_002-928e-12.20Page 2 Page 39001C_002-928e-12.20
Content
1. Introduction .................................................................................................................................4
2. Important instructions................................................................................................................5
2.1 For your safety....................................................................................................................5
2.2 Disposal instructions for electrical and electronic equipment .............................................6
2.3 Unpacking...........................................................................................................................6
2.4 Notes on handling the sensor.............................................................................................6
2.5 Tips on use of manual ........................................................................................................7
3. General.........................................................................................................................................8
3.1 Applications ........................................................................................................................8
3.2 Sensor design and principle of operation ...........................................................................9
4. Mounting....................................................................................................................................11
4.1 General aspects of mounting ...........................................................................................11
4.1.1 Pretension and preload .......................................................................................11
4.1.2 Sensor in direct path of force ..............................................................................13
4.1.3 Sensor in force shunt .........................................................................................13
4.2 Structural design and force contact ..................................................................................14
4.2.1 Examples.............................................................................................................14
4.3 Effect of elasticity conditions on the measurements.........................................................17
4.3.1 Calculations related to engagement of force.......................................................18
4.3.2 Examples.............................................................................................................21
4.4 Mounting example ............................................................................................................24
4.5 Installation of sensor family 90x1C and 910xC ................................................................25
4.5.1 Type 9422A: mounting for compression forces only ...........................................25
4.5.2 Type 9420A: Mounting for both compression and tensile forces.........................27
4.6 Installation of big force sensors Type 9081C and 9091C .................................................29
4.7 Installation of a Slimline Sensor Types 9130C … 9137C .................................................30
4.7.1 Direct force path mounting ..................................................................................30
4.7.2 Type 9410A: mounting in force shunt mode........................................................31
5. Measurement.............................................................................................................................33
5.1 Basic arrangement of a measuring system ......................................................................33
5.2 Range selection and threshold .........................................................................................34
5.3 Measuring high-frequency phenomena ............................................................................35
5.4 Measuring quasistatic phenomena...................................................................................35
5.5 Instructions and safety precautions ..................................................................................36
Total pages 55
6. Calibration and maintenance...................................................................................................37
6.1 In-Situ calibration of force sensors ...................................................................................37
6.1.1 Working point calibration by peak value comparison ..........................................37
6.1.1.1 Test system requirements....................................................................38
6.1.1.2 Reference sensor installation ..............................................................38
6.1.1.3 Load application...................................................................................39
6.1.1.4 Calibration process worksheet.............................................................40
6.1.2 Kistler calibration service.....................................................................................43
7. Troubleshooting........................................................................................................................44
7.1 Diagnosisandrecticationoffaults ..................................................................................44
7.2 Repairing Load Washer ....................................................................................................45
8. Technical data ...........................................................................................................................46
8.1 Optional accessories ........................................................................................................46
9. Appendix....................................................................................................................................47
9.1 Glossary ...........................................................................................................................47
9.2 Measurement uncertainty .................................................................................................50
9.3 Linearity ............................................................................................................................51
9.4 Frequency range ..............................................................................................................53
9.5 Inuenceoftemperature...................................................................................................54

Piezoelectric Force Sensors, Ring Force Transducers Important instructions
9001C_002-928e-12.20Page 4 Page 59001C_002-928e-12.20
1. Introduction
Thank you for choosing a quality product from Kistler.
Please read through this manual thoroughly to enable you
to fully exploit the various features of your product.
To the extent permitted by law Kistler accepts no liability
if this instruction manual is not followed or products other
than those listed under Accessories are used.
Kistler offers a wide range of measurement products
through to turnkey solutions:
Piezoelectric sensors for measuring pressure, force,
torque, strain, acceleration, shock and vibration
Strain gage sensor systems for measuring force and
torque
Piezoelectric pressure sensors and transmitters with
matchingmeasuringampliers
Matching measuring ampliers (charge ampliers, pi-
ezoresistive ampliers, etc.), displays and charge ca-
librators
Electronic control, monitoring and evaluation units as
wellassoftwareforspecicmeasurementapplications
Datatransmissionmodules(telemetry)
Kistler also develops and produces measuring solutions
fortheapplicationeldsengines,vehicles,manufacturing,
plastics and biomechanics sectors.
Our product and application brochures will provide you
with an overview of our product range. Detailed data
sheets are available for almost all products.
If you need additional help beyond what can be found
either on-line or in this manual, please contact Kistler‘s
extensive support organization.
2. Important instructions
It is absolutely essential to follow the instructions below,
which are intended to ensure your safety when working
with the equipment and guarantee a long, trouble-free
service life.
2.1 For your safety
Kistler force sensors have been thoroughly tested and
left the factory in perfectly safe condition. To maintain
this condition and ensure safe operation the user must
follow the instructions and warnings in this manual
Piezoelectric force sensors may only be mounted, used
and maintained by persons familiar with the equipment
andsuitablyqualiedfortheirparticularwork
If it has to be assumed that safe operation is no longer
possible, switch the equipment off and ensure it cannot
be switched on again inadvertently
It must be assumed that safe operation is no longer
possible when the product
shows visible signs of damage,
has been overloaded
is no longer operating,
has been in lengthy storage under unsuitable
conditions
has been subjected to rough transport conditions.
Mount the ring force transducer as specified. See section 4
„Mounting“ for details.
Secure all of the parts mounted on the force sensors
against the anticipated forces.

Piezoelectric Force Sensors, Ring Force Transducers Important instructions
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2.2 Disposal instructions for electrical and electronic equipment
Do not discard old electronic equipment in municipal trash.
For disposal at end of life, please return this product to
the nearest authorized electronic waste disposal service or
contact your Kistler sales office for instructions.
2.3 Unpacking
Check all of the packaging for any damage in transit,
which must be reported to the freight forwarder and the
responsible Kistler distributor.
Please check also for the completeness of the delivery
and report any missing parts to the responsible Kistler dis-
tributor.
2.4 Notes on handling the sensor
The specied environmental and operating require-
ments must be met when working with the sensor
The insulation resistance of piezoelectric sensors is of
criticalimportance;itmustmeetthevaluespeciedin
thedatasheet(upto1014 W).Toachievethisvalueall
plug connections must be kept scrupulously clean and
dry. The insulation resistance can be measured with
the corresponding insulation tester from Kistler
Protect all connector or cable parts between sensor
andchargeamplieragainstanydirt,andinparticular
make absolutely sure you never touch the front of any
connectorwithyourngers.Puttheincludedcoveron
if a connection is not being used
The cable for connecting the sensor to a charge amp-
lierisahigh-insulationtype.Ifnotincluded,useonly
suitable connecting cables or accesories specied by
Kistler
2.5 Tips on use of manual
We recommend that you read through the entire manual
thoroughly. However, if you cannot spare the time and are
already familiar with piezoelectric force sensors of Kistler,
you may skip to the sections with the information currently
required.
We have tried to organize this manual clearly so that the
required information is easily accessible.
Keep this manual in a safe place where it is readily acces-
si-ble at all times.
If you lose your manual please contact your Kistler distri-
butor for prompt replacement.

Piezoelectric Force Sensors, Ring Force Transducers General
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3. General
Piezoelectric force sensors are quartz crystal ring force
transducers. The force to be measured is transferred to
the quartz sensor elements via the cover plate and base
plate of the tightly welded steel housing. The quartz ele-
ments produce an electric charge proportional to the me-
chanical load. A charge amplier generates an electric
voltage from this charge. These signals are displayed, re-
corded or processed in the familiar way.
Thanks to the extremely high resolution of quartz it is pos-
sible to measure a change in force of the order of 1 N
under a pretension of several tons.
Theshape(loadwasher)andtherelativelysmalldimen-
sionsallowexibleapplicationandeasymounting.Stan-
dard accessories for special applications or mounting
conditions are available on the datasheets of the corres-
ponding sensor.
Sensitivity(chargeperunitforce)isaconstantofquartz
as a material. The associated threshold is virtually the
same for all the load washers of different sizes.
This has three unique advantages:
High level of overload protection, very small forces can be
measured with one sensor with a large measuring range
High rigidity; a sensor with a larger measuring range un-
dergoes less deformation
Several sensors can be electrically connected in parallel
toasinglechargeamplier.Theoutputsignalisthenthe
sum of all of acting forces
3.1 Applications
Kistler ring force transducers are very rigid and ideal for
measuring dynamic forces. This very high rigidity has ex-
tremely little effect on the dynamic characteristics of the
object being measured, in which they are mounted.
Depending on the size of the force, quasistatic measu-
re-ment can be performed over several minutes or even
hours(thesignaldriftisonlyabout±50mN/s).However,
truly static measurements over any length of time are not
possible.
On the other hand, after a pause of any length a sensor
undercontinuous static load(forexample, mounted ina
threadedconnection)canbereconnectedtoachargeam-
plierandthechangesinloadthenmeasuredaccurately.
Measurements of dynamic forces (AC mode) are also
possible over any length of time. Kistler load washers
have a virtually unlimited life and are not subject to sensi-
tivity drift caused by aging.
The force to be measured is transferred to the quartz sen-
sor elements via the cover plate and base plate of the
tightly welded steel housing. The quartz elements produce
an electrical charge proportional to the mechanical load.
Thesensitivity(chargeperunitforce,aconstantofquartz
as a material) and hence the threshold is virtually the
same for all of the different sized load washers.
3.2 Sensor design and principle of operation
A piezoelectric ring force transducer consists of one or
two crystal ring washers, an electrode and a housing with
connector(seeFig.1).
The force to be measured must be evenly distributed over
the ring surface. The mechanical compressive stress re-
sults in an electric charge being generated in the quartz
crystal. This charge is proportional to the applied force
and does not depend on the dimensions of the quartz
washers(longitudinalpiezoelectriceffect).

Piezoelectric Force Sensors, Ring Force Transducers Mounting
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a)
b)
S
Q = Quartz washers
E = Electrode
G = Housing
S = Connector
F = Force acting on the load washer
Fig. 1: Schematic section through a standard piezo-
electricringforcetransducera)andaSlimline
forcesensorb)
The generated charge is conducted from the electrode
and supplied to the plug connection. The polarity is cho-
sen so that a compression force generates a negative
charge, which is then converted into a positive voltage in
thechargeamplier.Thehousingservesasgroundcon-
nection. Unloading of the load washer produces a positive
charge.
Connecting several force sensors in parallel adds the
chargesoftheindividualsensorandthechargeamplier
measures the total force.
To ensure the forces to be measured are distributed even-
ly over the ring surfaces, the contact surfaces on the ob-
jectbeingmeasuredmustbeasat,rigidandnelyma-
chined as possible.
4. Mounting
If something is not clear or difculties are encoun-
tered when mounting piezo ring force transducers,
please contact the responsible Kistler distributor or,
if appropriate, the manufacturer, for advice. To enable
the query to be handled effectively it is important
to describe the measurement problem and provide
drawings or sketches that make the type of load,
engagement and point of application of the force
evident.
4.1 General aspects of mounting
Kistlerloadwashersmustbemountedbetweentwonely
machined(preferablyground),rigid,parallelsurfaces.This
allows force measurement over a wide frequency range.
TherecommendedsurfaceroughnessisRa=1,6μm.
4.1.1 Pretension and preload
Why to apply a pretension or preload:
Between the always imperfect surfaces inside and out-
side the sensor there are microgaps that act as inter-
posed spring elements. Preloading closes these gaps
to ensure force measurement is in the linear range and
freefromdisturbinginuences.(s.Fig.2)
Pretension eventually allows the measurement of both
compressionandtensionforces(s.Fig.3)
An optimal choice of preload allows to operate the sen-
sor in the range, where it is most robust against ben-
ding moments, which is at 50% of the nominal force of
thesensor.(4.3.1Calculationsrelatedtoengagement
offorce)
Pretension presses the contact surfaces together so
that the high rigidity of the sensor can be fully exploited

Piezoelectric Force Sensors, Ring Force Transducers Mounting
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Fig. 2: Linearity of force sensors Fig. 3: Measuring ranges depending on preload
Difference of pretension and preload:
The terms preload and preload force are often used as
synonyms, although they have a crucial difference: A
force is applied to the sensor by both preload and preten-
sion to overcome the nonlinear range of the sensor. How-
ever, when pretensioning a ring force transducer, a screw
is used through the center hole, resulting in a small force
shunt, which is not present with a pure preload. This force
shuntreduces the sensitivityofthe sensorby ≈5…10%,
depending on the layout.
Fig. 4: Pretension and the resulting force shunt through
bolt
How to preload:
When pretensioning, the force must be measured with the
sensoritself,andthechargeampliersettothesensitivity
speciedin thetechnicaldata.Asthepretensioningbolt
forms a force shunt, after being mounted the sensor
must be recalibrated to determine the sensitivity of the
complete measurement setup.
Calibratedsensorscomewithaspecicsensitivityvalue
for preloading.
4.1.2 Sensor in direct path of force
With direct force measurement almost the entire process
force passes through the sensor.
Fig. 5: Measurement in direct path of force
The total force applied (preload force Fv and process
forceFz)shallnotexceedthenominalforceofaringforce
transducer. Otherwise a bigger sensor has to be chosen.
In general, the force shunt effect of the preloading bolt is
neglectedwhenasensorsizehastobedened.Butifcir-
cumstances require it, the effective load on the quartz by
theprocessforceFzcanbereducedbythese≈5…10%
that are absorbed by the bolt. Check the datasheet of the
bolt accordingly.
4.1.3 Sensor in force shunt
Fig. 6: Example of indirect force measurement
If very large forces are to be measured or the sensor
cannot be positioned directly in the path of the force, it is
often mounted in a force shunt. This arrangement allows
the sensor to be used to solve a wide variety of measure-
ment problems. Due to it’s small dimensions, the Slimline
series 913x is very well suited for this purpose.

Piezoelectric Force Sensors, Ring Force Transducers Mounting
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4.2 Structural design and force contact
The full measuring range can only be exploited if the
force is evenly distributed. The mounting surfaces
should preferably be ground. Accessories like spherical
washers, force distributing rings, insulating washer and
force distributing caps make mounting easier in many
cases(seewww.kistler.com/force).Atthemaximumallo-
wed load of the particular load washer of whatever size a
surface pressure Gmaxofapproximately150N/mm2ari-
ses.
4.2.1 Examples
The ideal mode of force engagement produces an even
surface pressure on the ring force transducer and is free
from shear forces and moments. Several examples of
how force can be applied most effectively are listed below.
Measurement on rough surfaces
Contactsurfacesmustbeatandrigid.Iftheycannotbe
nely machined, localized overloads and damage to the
surface of the sensor must be avoided by using a force
distributingring(Fig.7).
Fig. 7: Mounting with a force distributing ring Type 95x5
on a rough surface
Measurement of a screw force
When measuring a screw force it is essential to avoid load
casea),asitcausesanoverloadattheinsideedge.To
ensure accurate measurement and exploitation of the full
measuring range, a matching element for introducing the
force must be manufactured.
Thebearingsurfacesontheloadwashermustbenished
by grinding. A good grease applied at the screw thread
and head (such as Kistler Type 1063) must be used to
reduce the friction.
Fig. 8: Measurement of force in a screw connection;
a)ineffectiveintroductionofforce,b)withcon-
structional element
Measurement of force between roughly machined
and/or oblique surfaces
Measurement between rough and/or oblique surfaces
should be avoided if possible (Fig. 9, case a). Machine
the mounting surfaces, preferably by grinding. A force dis-
tri-buting ring or a spherical washer should only be used
asatemporarysolution(Fig.9,caseb).However,under
load a spherical washer will no longer allow compensation
for misalignment.
Fig. 9: Force measurement between roughly machined
andobliquesurfaces,a)ineffectiveintroduction
offorce,b)withforcedistributingringandsphe-
rical washer
Measurement of a point force
A force distributing cap prevents introduction of force at a
point. If the plate is too thin it is deformed into a dish sha-
peandoverloadstheinsideedgeoftheloadwasher(Fig.
10,casea)inasimilarwaytotherstexampledescribed
(Fig.8,casea)).Asshownincaseb),theforcedistribu-
ting cap provides a remedy.

Piezoelectric Force Sensors, Ring Force Transducers Mounting
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Fig. 10: Measurementofapointforce;a)ineffective
introductionofpointforce,b)withforcedistribu-
ting cap
Measurement of force on a beam with two load
washers
Thedeectionofabeamsupportedontwoloadwashers
can result in local deformation of the washers (Fig. 11,
casea)).AsimpletrussarrangementasshowninFig.11,
caseb)providesaremedy.
Fig. 11: Measurement of force on a beam with two load
washers;a)ineffectiveapplicationofforce,b)
with simple truss arrangement
4.3 Effect of elasticity conditions on the measurements
With pretensioned connections, attention must be given to
the diversion of force without fail.
Fig.12showsitsinuenceasafunctionoftheelasticity
conditions, by means of stress-strain diagrams.
Ideally, the force shunt via the pretensioning elements is
very small, so that almost the entire force to be measured
is transmitted and measured by the load washer.
If the force shunt is large, it is still basically possible to
perform measurements, provided that the setup is calib-
rated. However, there is a risk that the magnitude of the
forceshuntmaychangeduringoperation(forexampleas
material compression, together with changes in tempera-
tureordeformations),andfalsifyingthemeasurementre-
sult despite calibration.
In all cases in accordance with Fig. 12 recalibration with
the washer mounted and pretensioned is necessary.
Examples
a) Theboltusedforpretensioninghasapproximatelythe
same rigidity as the load washer (with surrounding
elements).Eachofthetwopartstakeshalfoftheex-
ternal force F. The load washer only measures 50% of
theactingforceF(Fu=0.5F)
b) Iftheloadwasher(withsurroundingelements)iscon-
siderablymoreexiblethanthebolt,onlyasmallpro-
portion of the external force is measured (Fu <<F).
This solution should be avoided if possible
c) Iftheloadwasher(withsurroundingelements)iscon-
siderablymorerigidthanthebolt(idealcase),almost
theentireforceismeasured(Fu≈F).Theexactvalue
of the force shunt is determined by the calibration

Piezoelectric Force Sensors, Ring Force Transducers Mounting
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F: External force
FB: Force of the pretensioning bolt
FU: Force of the load washer
f: Elongation
Fig. 12: Effect of the elasticity conditions on the measu-
red result
4.3.1 Calculations related to engagement of force
If the force is applied eccentrically or the object being
measured deforms, bending moments arise. The resultant
bending stress is superimposed on the direct stress. In
thesecasesthemeasuringrangespeciedinthetableof
technical data no longer applies. The maximum allowed
surfacepressureσmaxmustnotbeexceeded.Themaxi-
mumallowedbendingmomentsspeciedinthetechnical
data can be used to determine the total load.
As a load washer cannot take tensile stresses, the direct
stress must always be greater than the bending stress.
The direct stress is produced by the sum of measured
force and pretension force.
Fig. 13 shows the general load case for a load washer,
with the pretension force FV, the axial force F and a side
force FSacting simultaneously.
Fig. 13: Combined load of force and bending moment
If the side force Fsis unavoidable, the following situation
happens:
Relative to the center of gravity of the load washer, the
side force Fsproduces a bending moment Fs· h. This re-
sults in the bending stress sB, which is counteracted by
the negative component of the measured force. On this
diagram the measured force F produces a relatively small
direct stress sF(sF< sB).Asaloadwashercannottake
any tensile stress, an additional force Fvmust be produ-
ced by means of a pretensioning bolt.
To prevent any tensile stresses forming, the maximum
bending stress sBmax. must remain under 50% of the ma-
ximum allowed direct stress smax.. This means that, in the
presence of the maximum allowed bending stress, the
measuring range of a load washer is reduced to 50%. If
the measured force F is less than 50% of the measuring
range, with a bending stress acting at the same time the
missing force Fvmust be applied by means of a pretensi-
oning bolt.

Piezoelectric Force Sensors, Ring Force Transducers Mounting
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It is also necessary to be aware of the requirement that
the side force Fsmust not exceed 10% of the direct force
(F + Fv) (based on a coefcient of friction m = 0.1). For
most applications this assumption includes a factor of sa-
fety against sliding of approximately 50%.
From the information in the technical data (Section 8)
(range=Fmax and max. MB),ifthepretensionforceFVand
the measured force F are known it is possible to make a
simpliedcalculationoftheallowedbendingmoment:
Case A Case B
Fig. 14: Load diagram
Case A: Rising range of load diagram
F+Fv≤½ · Fmax
Bending moment MB:
Case B: Falling range of load diagram
F+Fv≥½ · Fmax
If the bending moment is known the maximum allowed
force is determined by the pretension force and the meas-
ured force.
Case A:
Case B:
4.3.2 Examples
Example 1:
A load washer Type 9061C is mounted in the structure of
a machine in order to measure the forces generated, the
congurationissimilartothatshowninFig.13.
The following values are obtained from the technical data
of the datasheet:
Fmax = 140 kN
Mmax = 380 N·m
The load washer was pretensioned with 70 kN, the maxi-
mum allowed measured force is given as 30 kN. Case B
therefore applies. The side force acts at a lever arm of ap-
proximately 0.25 m. With these gures the following are
obtained for the maximum allowed side force:
and
In this example, as the measured force was substantially
less than the pretension force the maximum allowed va-
lues of the bending moment or lateral friction force (see
Example2)arenotexceeded.

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Example 2:
In the next example a measured force considerably hig-
her than the pretension force is assumed. The side force
FSthat produces a bending moment is also acting in this
case.
The technical data gives the following values for the sen-
sor Type 9102C:
Fmax = 50 kN
Mmax = 86 N·m
The measured force F is assumed to be 0 ... 30, the pre-
ten-sion force FVis 5 kN. The lever arm of the side force
FS is given as h = 0.1 m.
As FSacts continuously and independently of F, the worst
case is F = 0, and case A applies
F+ FV≤½·Fmax(CaseA)
and
Tocalculatetheno-slidingconditionthecoefcientof
friction of m= 0.1 is used with the smallest measured force
F = 0:
Fm=(F+FV)·m=(0kN+5kN)·0.1=0.5kN
Theno-slidingconditionissatised,asFS< Fm
Example 3:
The next example shows the case of a measured force
that acts eccentrically. The bending moment results from
the lever arm b. The sensor Type 9102C is considered
again, with the following values:
Fmax = 50 kN
Mmax = 86 N·m
The pretension in this case is given as FV= 10 kN, and
the measured force F is limited to the range 0 ... 30 kN. As
the side force FSis dependent on the measured force F,
case B applies. As the moment is produced by the mea-
suredforce,theformulacanbemodiedtocalculatethe
allowed distance b.
If the full measuring range of the sensor is to be exploited
by the measured force, it must therefore be certain that
the force acts at the center of gravity of the sensor.

Piezoelectric Force Sensors, Ring Force Transducers Mounting
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4.4 Mounting example
An example of mounting a bearing shows the effect of the
way the force is applied and the load path.
In Fig. 15 the load washer has been mounted between
angeandfoundation,oralternativelybetweenangeand
bolt head. If a force acts on the bearing, in the case on
the right the greater part of the force is measured with the
load washer. The proportion involved in the force shunt
approximately corresponds to the ratio of the rigidity of the
load washer on the one hand, to the rigidity of the shank
of the bolt between its head and the foundation on the
other.
The situation is much worse with the alternative mounting
congurationon the left.If,for example, aforceacts on
the bearing in the direction of the foundation, the bearing
angetakesalmostallofit.Estimationoftheratioofthe
rigidityofthebearingangeonthefoundationontheone
hand, and the rigidity of the bolt with load washer on the
other, quickly makes it evident that the force shunt for the
loadwasherisverysmall.The more rigid the ange the
lower the proportion of the force that can be measured by
the load washer.
Fig. 15: Example of bearing force measurement
4.5 Installation of sensor family 90x1C and 910xC
4.5.1 Type 9422A: mounting for compression forces only
àuse the preloading element set Type 9422A… from
Kistler(includedatsensorsType9001…9051).
àmore detailed information about the required setup
(dimensionsetc.)canbefoundinthedatasheetofthe
Type 9422A… .
1. Themountingsurfaceshavetobeat,rigidand
ground.
2. Carefully clean the bearing surfaces on the base
plate, the cover plate and the sensor with a
degreasingcleaner(suchasethanol).
3. Attach the centering sleeve to the screw.
4. Loosely assemble the sensor according to drawing
Fig.16.
a)Optional:putinsulationwashersonthecontact
surfaces of the sensor, if the sensor shall be
mountedground-insulated(Kistleraccessory
Type95x8).
5. Grease sparingly the head and thread of the
preloading bolt with Kistler special grease Type 1063.
(inordertoreducetorquestransmittedtothesensor
duringpreloading).
6. Connectyourchargeampliertothesensorandset
thesensitivitytothevalueprovidedinthedatasheet/
calibrationsheet(fullrangevalue).
7. Applythedesiredpreload(refertochapter4.1.1)by
tightening the screw and checking the resulting force
shownonthechargeamplier.Donotexceedthe
maximum pretension force.
8. Make sure the screw is slightly recessed with regard
to the surface of top and bottom plate.
èdo not correct the preload by turning the screw coun-
terclockwise!
èjust start preloading again from 0 kN instead!
èUse a new screw in case you exceeded the load limit.

Piezoelectric Force Sensors, Ring Force Transducers Mounting
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Fig. 16: Detailed dimensions for sensor installation are
available on the datasheet of Type 9422A...
4.5.2 Type 9420A: Mounting for both compression and tensile forces
àuse the high-strength preloading element set
Type 9420A… from Kistler
àmore detailed information about the required setup
(dimensionsetc.)canbefoundinthedatasheetof
Type 9420A…
1. Themountingsurfaceshavetobeat,rigidand
ground.
2. Carefully clean the bearing surfaces on the base
plate, the cover plate and the sensor with a
degreasingcleaner(suchasethanol).
3. Applyanadhesive(e.g.Loctite121)ononeofthe
threads of the bolt.
4. Screw the bolt with the adhesive treated end into the
base plate.
5. Attach the centering sleeve to the screw.
6. Loosely assemble the sensor according to drawing
Fig.17.
a)Optional:putinsulationwashersonthecontact
surfaces of the sensor, if the sensor shall be
mountedground-insulated(Kistleraccessory
Type95x8).
7. Grease sparingly the upper thread of the preloading
bolt and the contact surface of the pretension nut with
Kistler special grease Type 1063.
8. Connectyourchargeampliertothesensorandset
thesensitivitytothevalueprovidedinthedatasheet/
calibrationsheet(fullrangevalue).
9. Apply the desired preload by tightening the screw
and checking the resulting force shown on the charge
amplier.Recommendedpreloadforpressand
tensile forces is around 50% in order to achieve the
highest stability regarding bending moments plus a
decentrangefortensileforces(refertoch.4.1.1).
10. Do not exceed the maximum pretension force of the
bolt. In case you need to reach higher preloads, you
will have to another bolt or contact Kistler for advice.
11. Make sure the bolt ends are not directly exposed
to a force induction. The measured force has to be
distributed by the top and the bottom plate.
èdo not correct the preload by turning the screw coun-
terclockwise!
èjust start preloading again from 0kN instead!
èUse a new screw in case you exceeded the load limit.

Piezoelectric Force Sensors, Ring Force Transducers Mounting
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Fig. 17: Detailed dimensions for sensor installation are
available on the datasheet of Type 9420A
4.6 Installation of big force sensors Type 9081C and 9091C
Kistler provides two preloading element sets with espe-
cially strong bolts for the big force sensors:
– Type9455(forType9081Csensors)
– Type9456(forType9091Csensors)
Basically, the mounting procedure is the same like in
chapter 4.5.2 with Type 9420, with one decisive diffe-
rence:
èThe preload must be applied by a hydraulic press,
before the nut is tightened
Thepreloadof400kN/600kNistoohightobeappliedby
tightening the nut.
Contact Kistler to get your big force sensors Type 9081C
Type and 9091C mounted properly into your own struc-
ture.
Fig. 18: Load washer pretensioned with set
Type9455/9456.Detaileddimensions
are available on the datasheet

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4.7 Installation of a Slimline Sensor Types 9130C … 9137C
Do not allow any grease to get onto the surface of thesensor.
The head bearing surface and thread of the preloading bolt
must be greased before the bolt is screwed in.
4.7.1 Direct force path mounting
1. The mounting surfaces have to be at, rigid and
ground(Fig.9).
2. Carefully clean the bearing surfaces on the base pla-
te, the cover plate and the sensor with a degreasing
cleaner(suchasethanol).
3. Grease sparingly the head and thread of the preloa-
dingboltwithKistlerspecialgreaseType1063.(inor-
der to reduce torques transmitted to the sensor during
preloading).
4. Loosely assemble the sensor according to drawing
Fig. 19.
5. Connectyourchargeampliertothesensorandset
the sensitivity to the value provided in the datasheet.
6. Slowly apply the desired preload (refer to chapter
4.1.1)bytighteningthescrewandcheckingtheresul-
tingforceshownonthechargeamplier.
7. Make sure the screw is slightly recessed with regard
to the surface of top and bottom plate.
èdo not correct the preload by turning the screw coun-
terclockwise!
èjust start preloading again from 0kN!
èUse a new screw in case you exceeded its load limit.
Fig. 19: Here you can see how the sensor is loosely
assembled.
Mount. dim.
Type
Thread Bore diameter
D1 [mm]
Plate
thickness 1)
A [mm]
9130C... M2,5 2,9 8,0
9132C... M4 4,3 8,0
9133C... M6 6,4 12,0
9134C... M8 8,4 16,0
9135C... M10 10,5 20,0
9136C... M12 13,0 24,0
9137C... M14 15,0 27,0
1)Recommended minimum value
4.7.2 Type 9410A: mounting in force shunt mode
Preferably mount the Slimline sensor with the preloading
boltanddiskType9410A..fromKistler(optionalaccessory).
1. Grindthestructureaccordingtotheexampleing.16
2. Carefully clean the bearing surfaces on the base pla-
te, the cover plate and the sensor with a degreasing
cleaner(suchasethanol).
3. Grease sparingly the head and thread of the preloa-
dingboltwithKistlerspecialgreaseType1063.(inor-
der to reduce torques transmitted to the sensor during
preloading).
4. Loosely assemble the sensor according to drawing
Fig. 21.
5. Connectyourchargeampliertothesensorandset
the sensitivity to the value provided in the datasheet.
6. Applythedesiredpreload(min.20%ofnominalforce)
by tightening the screw and checking the resulting
forceshownonthechargeamplier.
7. Grind the structure and preloading bolt in conjunction
with the mounted & preloaded sensor.
8. Remove the sensor.
9. Re-grindthestructurewithoutinfeed(toachieve the
slight projection P and ensure a reproducible force
shuntandgoodlinearity).
10. Perform step 2 … 6 again to install the sensor into the
structure.
11. Make sure that at the end the screw head is slightly
recessed with regard to the surface of the preloading
disk.
12. Assembly the upper part of the structure.
èdo not correct the preload by turning the screw coun-
terclockwise!
èjust start preloading again from 0kN!
èUse a new screw in case you exceeded its load limit.

Piezoelectric Force Sensors, Ring Force Transducers Measurement
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Fig. 20: Mounting in force shunt
Fig. 21: Mounting with preloading disk Type 9410A...
Fig. 22: Assembling with preloading disk Type 9410A...
5. Measurement
5.1 Basic arrangement of a measuring system
A measuring system is assembled from a quartz crys-
tal load washer, a highly-insulated low-noise connecting
cableandchargeamplier,adisplayand/ordataacquisi-
tion and processing unit.
Fig. 23: Measuringsystemconguration
Inthechargeampliertheelectricalchargegeneratedby
the sensor is converted into a proportional voltage, which
may be displayed, recorded or further processed. The
con-necting cable for the transducer must be highly insu-
latingandlow-noise.Theeffectof the cable length(>15
m) can be obtained from the instruction manual for the
chargeamplieremployed.
Fromthechargeampliertothedisplayorrecorder,ordi-
nary coaxial cables may be used.

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5.2 Range selection and threshold
A distinction must be made between the measuring range
oftheloadwasherandthatofthechargeamplier.When
thecorrectpre-loadhasbeenapplied(chapter4.1.1,Fig.
3), the measuring range of the sensor can be chosen
freely, even down to 1% of the nominal force or less, with
roughly the same linearity. Of course, a calibration of the
corresponding range is recommended - on site or at Kist-
ler.
The measuring range desired for performing a measure-
ment can be selected freely on the charge amplier (for
example Kistler Type 5015A…). Charge amplier Type
5015A… provides continuous measuring setting ranges.
Together with load washers the following forces ranges in
Nresults:1…50,000N/Vor10Nto500kNfor10Vout-
put voltage. Of course the maximum admissible force for
the load washer in use must not be exceeded. For ranges
above50kNthereisthechargedivider10:1(forexamp-
leKistlerType5361).
It is for example possible to select a measuring range of
10Nandmeasuresmallforceuctuationssuperimposed
onastaticpretensionof,say,10kN.Brieyoverloading
small measuring ranges by a factor of 50 does not nor-
mallyharmthechargeamplier.Withbiggeroverloadsit
depends on the capacitance of the input cable whether
theamplierisdamagedornot.
Theinstructionmanualfortheparticularchargeamplier
used will provide information regarding is overload capa-
city.
For practical purposes at least, the threshold of a load
wash-ermayberegardedasinnitelylow.Togetherwith
a stand-ard charge amplier the practical limit is around
0,01N(signal-to-noiseratioabout50%).
5.3 Measuring high-frequency phenomena
Thanks to their high rigidity, quartz piezoelectric force
sensors are eminently suited for measuring rapidly chan-
ging processes. As the mounting situation has a decisi-
veeffect,thenaturalfrequenciesspeciedinthetableof
technical data are more of theoretical importance.
If a load washer is installed into a cylinder of the same
diameter for measuring axial force, it can be said without
contradiction that the dynamic properties of the measu-
ring object are not affected by installing the load washer.
There is no need whatever to take the natural frequency
of the load washer into consideration.
If on the other hand a large mass has to be supported
on three or four load washers, this assembly constitutes a
spring-mass oscillator. Obviously the natural frequency of
this system depends on the rigidity and not on the natural
frequency of the load washers and the magnitude of the
mounted mass. The natural frequency becomes higher as
theloadwashersusedbecomelarger(thatismorerigid).
The fact that the natural frequency of a larger load washer
is itself smaller is not important as far as the natural fre-
quency of the system is concerned. Thus dynamometers
with natural frequencies of several kHz can readily be ma-
nufactured.
Force links assembled from load washers Type 93x1C,
have natural frequencies from 22 to 85 kHz, depending on
size and weight.
5.4 Measuring quasistatic phenomena
Purely static measurements over any length of time are
not possible with the piezoelectric measuring principle.
The time interval during which so-called quasistatic meas-
urements can be performed depends on the insulation re-
sistance of the sensor and connecting cable on the pro-
pertiesofthechargeamplieremployed.
Withaninsulationresistanceof >1013 W and <0.04 pC/s
amplier drift current, a time-dependent error of about
±0,5 N/min results using a load washer. Assuming a
measuring range of 5 000 N, this value implies an error of
0,1%(5N)ifthemeasurementlasts10minutes.
If the temperature of the transducer changes during the
measurement, a similar error signal must be expected;
this is often called the „temperature drift“. It is caused by
mechanical stresses acting on the quartz washers as a

Piezoelectric Force Sensors, Ring Force Transducers Calibration and maintenance
9001C_002-928e-12.20Page 36 Page 379001C_002-928e-12.20
result of thermal expansion. Changes in the temperature
in the structure in which the sensor is mounted also often
haveaneffect.Differentcoefcientsofthermalexpansion
can lead to deformation of the structure.
In principle a quartz load washer measures not the abso-
lute amount of a force but only changes of force. Normally
the force change is measured between the unloaded and
loaded states. With pretensioned force links the unloaded
statemaybedenedataneffectivepretensionofseveral
tons.
The quasi-static properties of a charge amplier are de-
scribed in the relevant instruction manual.
5.5 Instructions and safety precautions
Thesupportingsurfacesforaloadwashermustbe-
nelymachined(Ra=1.6),atandrigid
The maximum measuring range may be exploited only
if the force is distributed uniformly over the entire sup-
porting surface
With uneven surface loading, due to superimposed
exureforexample,themaximummeasuringrangeis
limited not by the range given in the table of techni-
caldatabutbythehighestlocalsurfacepressure(see
chapter4.2)
If a load washer is used to measure screw force, the
frictionsurfaceshouldbe lubricated well(special gre-
ase Type 1063). With high surface pressure a thin
washer of beryllium copper will prevent pitting
To maintain the high insulation resistance the connec-
ting plug must be kept clean. The same applies to the
plug of the connecting cable. If necessary they should
becleanedwithFreonorrectiedbenzene.Ifthecable
is disconnected from the sensor, the protective cover
should be screwed on in its place
If trouble is encountered due to ground loops, the load
washer can be insulated from the object mass with so-
called insulating washers Type 95x7
6. Calibration and maintenance
6.1 In-Situ calibration of force sensors
Absolute measurement results can only be made if the
complete measurement assembly, e.g. the pretensioned
loadwasherand itsmountingxtures,hasbeencalibra-
ted.
If it is possible to remove the force measurement assem-
bly, without inuencing the pretension and load distribu-
ting of the force sensor, the assembly can be sent to a
Kistler Calibration Centre for recalibration. If, however, the
sensor is integrated into the machine structure, it normally
is not possible to remove the force measurement assem-
bly for recalibration. In this case an in-situ calibration must
be performed.
6.1.1 Working point calibration by peak value comparison
The test system is calibrated by comparing its output with
that of a reference measurement chain at loads around a
specicworkingpoint.Anaveragesensitivityiscalculated
from the peak values of both the reference and test sys-
tems recorded over multiple load cycles.
It is important to note the calculated sensitivity, S*, is valid
foraspecicmeasurementchain,i.e.sensor,chargeam-
pli-eranddisplayunit.Exchangingsensorsorampliers
will make the calibration invalid.
Furthermore, the sensitivity S* is calculated around a spe-
cic working point and will invariably differ slightly from
any works calibration results, which would have been de-
rived using a standard continuous calibration procedure.
It is generally also recommended to check the distribution
of the average sensitivity by calculating the standard devi-
ation of the sensitivity S*.