Sensor integration
Fully integrated sensor technology in the thread base
Continuous measurement
Real-time measurement of prestressing force and dynamic loads
Focus on
mechanics
No weakening of the fastener – full mechanical integrity
All forces
at a glance
Versions for axial force, bending, and torsion
The S.Bolt XP was developed specifically for applications where the mechanical integrity of bolted connections is a top priority.
A key feature is the sensor technology that is fully integrated into the thread base. This design enables the measurement of axial forces (S.Bolt XA), bending (S.Bolt XB), and torsion (S.Bolt XT) without compromising the structural strength of the bolt. Unlike conventional solutions, where drilling or external cable channels can alter the mechanical properties, the S.Bolt XP retains its full function as a connecting element.
The combination of standard-compliant design and innovative sensor integration makes the S.Bolt XP ideal for safety-critical applications in industry, energy, and infrastructure.
Operating principle
The mechanical integrity of the S.Bolt XP is achieved by means of sensor technology that is fully integrated into the thread base. Unlike conventional solutions, which require drill holes or external cable channels and thus reduce cross-sectional strength, the bolt body remains unchanged in the S.Bolt XP.
The sensors are designed as strain gauges in a Wheatstone full bridge and positioned so that they detect axial strain and, optionally, bending and torsion without affecting the load-bearing capacity.
Versions
S.Bolt XA
S.Bolt AB
S.Bolt AT
Measurement direction
Axial (bending compensated)
Axial (bending compensated)
Bending on 2 axes
Axial (bending compensated)
Torsion
Sensor type
1x Wheatstone full bridge
3x Wheatstone full bridge
2x Wheatstone full bridge
Electrical connection
M12-A socket
4 pole
M12-A socket
8 pole
M12-A socket
8 pole
Temperature measurement
Optional
No
No
Robust Version
S.Bolt XAR
with reduced cross-section
S.Bolt ABR
with reduced cross-section
S.Bolt ATR
with reduced cross-section
Minimum diameter
M24 standard thread
M36 standard thread
Not available for fine thread
M36 standard thread
Not available for fine thread
Typical applications
Wind power
Steel construction
Special machine construction
General applications for measuring preload and dynamic loads.
Sheet bolts
Tower flanges
Crane runways
Bridges
Tunnel boring machines
Presses
Foundation bolts
Critical Bolted Joints under Bending Loads
Blade Bolts
Tower Flanges
Long screws and bolts that are installed using rotating methods.
Blade bolts
Foundation bolts
Foundation bolts
Frequently asked questions
FAQ
What is the S.Bolt XP and what is it used for?
The S.Bolt XP is a standard-compliant bolt with integrated sensors for measuring preload force and dynamic loads. It is used in safety-critical applications such as wind turbines, bridge construction, and mechanical engineering.
What is the minimum thread size for which the S.Bolt XP is available?
The S.Bolt XP is available for threads from M24 upwards. For very large threads (M72 and larger), Sensorise recommends using S.Ring M.
Is there a calibration?
Uncalibrated, the error is < 5%, which is sufficient for most practical applications.
On request, calibration according to ISO 376 up to 7500 kN can be provided.
I want to monitor a ring flange with 120 bolts. Does every single bolt have to be an S.Bolt?
No.
In general, the more regular the dynamic operating forces are (e.g., due to rotation), the fewer measuring points are required. Continuous measurement allows signal changes to be detected much earlier than would be possible with individual measurements.
In ring flanges with continuous excitation (e.g., rotor blade flanges in wind turbines), 4 bolts (90°) should be replaced with S.Bolts.
In other applications, it is common to monitor 10% of the bolts with sensors.
Does sensor integration weaken the screw mechanically?
No. The sensor technology is fully integrated into the threaded base. There are no drill holes or external cable channels that could compromise strength.
Can the S.Bolt XP be retrofitted?
Yes. It replaces a standard bolt without any design changes to the component.
What loads can the S.Bolt XP measure?
S.Bolt XA: Axial preload force
S.Bolt AB: Axial force + bending
S.Bolt AT: Axial force + torsion
The measurement signal continues to rise after the tool has been set down. What am I doing wrong?
The bolt has reached or exceeded its yield point and is undergoing plastic deformation.
How is it installed?
Installation is carried out in the same way as for a normal bolt – using standard tools and familiar methods (torque or pulling method). Special adapters or additional calibration aids are not required.
How is the S.Bolt connected?
The connection is made via an A-coded M12 industrial connector. Most commercially available measuring force amplifiers can process the signals.
My tool already measures torque. Why should I measure preload force?
The achievable preload force in rotating processes is largely determined by the friction properties of the contact surfaces (thread, nut, etc.). Deviations of 20% - with identical tightening torque - are not uncommon.
I loosened the bolt and the zero point shifted. Is the sensor defective?
The zero point shift in highly preloaded screws is caused by plastic settling and relaxation in the material structure. At very high preload forces (close to the yield point), microscopic rearrangements occur in the thread and on the contact surfaces.
In addition, inhomogeneous residual stresses from heat treatment and local flow processes at the thread root can influence the strain gauges. These effects lead to a change in the output signal, even though the actual preload force remains constant.
This behavior is taken into account in VDI 2230 and ISO 16047. The recommended practice is to perform a tare after assembly in order to reference the measuring chain to the new stable state.
What is your application?
Contact us
Sensorise GmbH
Fahrenheitstraße 1
28359 Bremen
Germany
+49 (0)421 220 834 0
