Force Sensor K Series – for precise measurement of tensile and compressive forces

Our force sensors utilize the bending ring principle as the sole integrated measurement method in force measurement.
This enables highly precise measurement of tensile and compressive forces across the entire measurement range, from the lowest load (200 N) to the rated force (630 kN).

Kraftaufnehmer Serie K - Präzise, robuste und konfigurierbare Kraftmesssensoren von 200 N bis 630 kN

What sets the K Series force transducers apart?

The K Series is a force sensor that enables high-precision measurement of tensile and compressive forces across the entire measurement range—from the smallest load to the rated force. Thanks to the flexural ring principle, these force sensors are largely insensitive to so-called parasitic influences such as shear forces, bending moments, torsional moments, and temperature fluctuations.

The force sensors are ideal for static and dynamic testing processes, for quality assurance and process control in complex production processes, as well as for component and material testing. They are robust and durable, withstanding forces up to 300% of the rated force without breaking and up to 150% of the rated force without zero-point drift.

Key features of the force sensors at a glance:

Rated force range: 200 N to 630 kN
Accuracy class 0.02 to 0.05
Tensile and compressive forces, static and dynamic
Robust construction, protection class up to IP68
Very low susceptibility to parasitic influences
High overload capacity
Over 13,000 possible variants

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K Series Force Sensor - Technical Specifications

The K Series force sensor is designed for nominal forces ranging from 200 N to 630 kN and, depending on the configuration, meets accuracy classes ranging from 0.02 to 0.05. The technical specifications are clearly organized by category below. In addition, you can download STEP and IGES files, technical data sheets, operating instructions, and the Declaration of Conformity here.

What technical advantages does the force sensor offer?

Accuracy: Accuracy class 0.02 to 0.05; linearity deviation 0.02–0.03%.
The bending ring principle: The only integrating measurement method in force measurement technology.
Insensitivity to parasitic influences: Low sensitivity to transverse forces, bending moments, torsional moments, and temperature fluctuations.
Dynamic suitability: Fatigue strength > 100 million load cycles; amplitude up to 80% (at 2 mV/V) or 100% of rated force (at 1 mV/V)
Overload protection: 150% of rated force without zero-point shift; breaking force only at 300% of rated force
Protection class: IP68 with fixed cable connection; IP50 with plug connection
Temperature range: Standard: −10 °C to +60 °C; optional: −40 °C to +180 °C
Configurability: Flange, threaded, or combination design; cable or connector; nominal ratio 1 or 2 mV/V; optional redundant measurement circuit and bending moment measurement circuits

Technical Specifications of the Force Sensors at a Glance

General Information
Rated force range	0.2 to 630 [kN]
Linearity deviation	0.02–0.03 [%]
Hysteresis	0.02–0.08 [%]
TK_C characteristic value	0.04 [%/10K]
TK_o zero signal	0.025 [%/10K]
Design	(1) Flange (2) Center thread (3) Flange & center thread*depending on rated force

Mechanical Specifications
Fatigue strength	1. Amplitude ≤ 80% Fnom @2mV/V 2. Amplitude ≤ 100% Fnom @1mV/V
Maximum overload	150 [%]
Static breaking force	300 [%]
Fatigue strength / cycles	Fatigue strength >10⁸
Sensor body material	1. 0.2 kN – 0.5 kN: high-strength aluminum alloy 2. 1 kN – 630 kN: quenched and tempered steel
Hermetically sealed	Yes
Electrical connection	1. Fixed connection socket on the housing 2. Cable with open ends or selectable and pre-assembled connectors

Electrical Specifications
Rated value	2 or 1 [mV/V]; depending on the rated force
Bridge resistance	900–1200 [ohms]; depending on the rated force
Zero signal tolerance	0.5 [%]
Nominal supply voltage range	5–20 [V]

Environmental Conditions
Nominal temperature range	-10 to +60 [°C]
Extended operating temperature range	-40 to +180 [°C]
Protection class	IP68, with fixed cable connection ; IP50, with plug connection

What variants and options are available?

The K Series force sensor is a configurable measurement system. Various models are available depending on the rated force, installation conditions, environmental conditions, and measurement task.
An overview of the most important options:

Application-specific designs: Redundancy and bending moment measurement

For particularly demanding measurement tasks, these force sensors offer two advanced options:

Second axial measurement circuit (redundancy):
A second independent measurement circuit enables simultaneous measurement of the same force via two separate signal paths. This is useful in safety-critical applications or wherever a signal failure is not tolerable, such as in automated test lines or test procedures requiring certification.

Bending moment measurement circuits Mx, My:
This option allows for the detection of bending moments in two axes in addition to the axial force. This is useful when monitoring the quality of force application, for example, to detect eccentric loads in the test setup at an early stage and to document the measurement conditions.

Mechanical options: flange, threaded, or both

Depending on the rated force, these force transducers are available in three basic mechanical designs:

Flange: Suitable for installation in test frames and testing machines with a defined mounting surface; high stiffness in the force transmission path.
Threaded: For space-saving integration into test fixtures or machines with threaded connections.
Flange & Thread: For flexible installation scenarios where both connection types are required or the mounting orientation must be variable.

Environmental requirements: Extended temperature range

By default, the K-series force sensors are designed for temperatures ranging from −10 °C to +60 °C. For more thermally demanding environments, an extended temperature range of −40 °C to +180 °C is available as an option.

When is this option relevant?

Test benches in climate chambers with low temperatures.
High-temperature applications in materials testing.
Outdoor applications with significant seasonal temperature fluctuations.
Processes with increased heat generation in the production environment.

Connection options: plug or fixed cable

The choice of electrical connection has a direct impact on the protection rating, handling, and system integration.

Fixed connection socket on the housing: IP50, for laboratory environments, dry test benches, and frequent sensor replacement.
Fixed cable (various lengths): IP68, for wet environments, coolant use, permanent installations.

With a fixed cable, various connector types are available—D-Sub, MS, M12—or open cable ends for custom assembly.

For which applications is the force sensor suitable?

Force sensors are used worldwide in testing machines, materials and component testing, industrial process control, quality monitoring,
calibration laboratories, and research and development—offering precision, reproducibility, and durability.

Force sensor in testing machines

In static and dynamic testing machines, the force sensor provides precise, reproducible measurements across the entire load range. Thanks to its fatigue strength (> 100 million load cycles), it operates reliably even in endurance and fatigue tests without requiring frequent recalibration.

Force sensor for dynamic force measurements

Vibrations, rapid load cycles, and impact forces can distort measurement results. The flexural ring principle structurally dampens the effects of lateral forces, bending moments, and torsion without the need for software-based correction. The force sensor is therefore suitable for high-frequency test cycles and dynamic load profiles.

Force sensors in materials and component testing

Force sensors can withstand overloads of up to 150% of the rated force without any shift in the zero point. Their breaking load is 300% of the rated force, and they can often withstand sudden component failure. At the same time, they measure small forces with high resolution (relative measurement error < 0.05%).

Force sensor for industrial process control and quality assurance

Force sensors monitor and document joining processes, pressing operations, or assembly steps. Within the specified measurement range, they provide highly linear measurements. Depending on the model, a single sensor can cover a wide range of loads. This simplifies sensor selection and reduces total cost of ownership.

Force Sensor FAQ

A force sensor is a measuring device that converts mechanical forces (compression or tension) into an electrical signal. Most force sensors are based on strain gauge technology (SG): An applied force causes minimal deformation of the sensor body, and this deformation is output as a proportional voltage signal. Force sensors are classified into accuracy classes—the lower the value, the more precise the measurement result.

Force sensors are used wherever forces need to be measured, monitored, or recorded. Typical applications include materials and component testing, testing machines, industrial manufacturing and quality control processes, and calibration laboratories. They are also indispensable in research, mechanical engineering, and the automotive industry.

An applied force causes the metal sensor body to deform elastically. Strain gauges attached to the sensor body detect this deformation as a change in resistance, which is converted into a voltage signal (typically in mV/V) in a bridge circuit. A downstream measurement amplifier detects and processes this signal.

A force sensor is calibrated by comparing its measured values with traceable reference forces. To do this, the sensor is subjected to a defined load in a calibration setup, usually at several load levels between zero and the rated force. The applied force is determined using highly accurate reference systems (e.g., dead weights or reference force sensors). For each load step, the output signal is recorded and compared with the setpoint. This yields characteristic values such as sensitivity, linearity, and hysteresis.

Calibration is performed in accordance with international standards such as DIN EN ISO 376. Load cycles, preloads, and defined measurement points are specified to ensure reproducible results. It is also important to document the environmental conditions, particularly the temperature. As a laboratory accredited according to DIN EN ISO/IEC 17025, GTM ensures that calibration is performed according to established procedures and is traceable to national standards. The result is a calibration certificate that transparently reports the deviations and measurement uncertainty. Regular calibrations are crucial for ensuring measurement accuracy over the long term.

Force sensors are available with ranges from a few newtons to several meganewtons. To obtain accurate measurement results, the rated force should be selected so that the expected measurement forces fall within the middle to upper range of the sensor.

Yes, most force sensors are designed to measure force in both directions. This requires that the sensor be mechanically designed for both tension and compression and installed accordingly. The data sheet specifies whether both directions are supported.

The measurement results of a force sensor are influenced by numerous external and internal factors. Mechanical influences such as lateral forces, bending moments, or eccentric force application can lead to significant measurement errors. These can be minimized through proper, centered installation and the use of appropriate force application elements. The installation environment (e.g., stress or uneven support surfaces) also plays an important role. Temperature is another critical factor.

Changes in temperature lead to material expansion and electrical drift effects. Temperature-compensated sensors and stable environmental conditions can mitigate this. Electrical interference such as noise or poor shielding can distort the signal; high-quality amplifiers and proper cabling help here. Time also affects the result: effects such as creep or drift occur particularly during long measurements. Regular calibration and sufficient settling time are therefore important. Finally, operator errors, incorrect scaling, or unsuitable signal conditioning electronics can also degrade accuracy. Careful selection of the measurement chain and clear process control are crucial for achieving reproducible and reliable results.

Force sensors are based on various physical principles. The most common are strain gauges (SG), in which the electrical resistance changes due to mechanical strain. Piezoelectric sensors generate an electrical charge when force changes and are particularly suitable for dynamic measurements. Capacitive sensors measure the change in the electric field caused by deformation. Hydraulic or pneumatic systems convert force into pressure. Optical or magnetoelastic methods are used less frequently. The choice of principle depends on requirements such as measurement range, dynamics, accuracy, and environmental conditions.

These terms describe different sources of error and behaviors of a force sensor.
- Linearity indicates the degree to which the actual characteristic curve deviates from an ideal straight line. The more proportional the sensor’s output signal is to the applied force, the more
linear the sensor is.- Hysteresis describes the difference in the output signal when the same force is applied once from below (loading) and once from above (unloading). It arises from internal material effects and friction.
- Repeatability (reproducibility) evaluates how consistently a sensor measures under multiple identical loads under the same conditions. It is a measure of the dispersion of the measured values
.- Creep describes a time-dependent change in the signal under a constant load. This means: Even if the force remains the same, the output signal continues to drift slowly.

These effects occur simultaneously but have different causes. While linearity and hysteresis are primarily material- and design-related, repeatability depends heavily on stability and noise. Creep is influenced by viscoelastic properties. For precise measurements, all four parameters must be taken into account, as they directly affect the total uncertainty.

The sensor body undergoes minimal deformation when subjected to force. Thanks to the bending ring principle, the applied force is distributed across the entire ring—resulting in extremely linear and repeatable measurement results, while also offering low sensitivity to parasitic influences.

Why this is important:

High measurement accuracy
Excellent reproducibility
Minimized sources of error

The accuracy of force transducers is described by several parameters that together constitute the total measurement uncertainty. These include linearity deviation, hysteresis, repeatability, creep, and the influence of temperature and transverse forces. Manufacturers typically specify accuracy as a percentage of the full scale (e.g., ±0.1% FS). This is based on calibrations according to international standards (e.g., ISO 376), in which defined forces are applied and deviations are evaluated.

Force Sensor K Series – for precise measurement of tensile and compressive forces

What sets the K Series force transducers apart?

Key features of the force sensors at a glance:

Already have your product code?

Or start your individual configuration!

Do you need additional support?

K Series Force Sensor - Technical Specifications

STEP Data

IGES data

Data Sheet

User Manual

Declaration of Conformity

What technical advantages does the force sensor offer?

Technical Specifications of the Force Sensors at a Glance

General Information

Mechanical Specifications

Electrical Specifications

Environmental Conditions