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Measuring force where it's hot: High-temperature force transducers, load cells, and sensor technology
Force measuring pins, force transducers, and load cells from octogon are available for a continuous operating temperature of 250 °C. Not as a short-term peak that a standard transducer might just survive, but as an operating temperature at which the sensor maintains its specified accuracy.
If you are interested in the temperature itself rather than force, our range of sensors with thermocouples goes much further, up to 1,200 °C. Many systems require both, and we supply both.
Why temperature is a problem for force measurement
A load cell measures the deformation of a measuring body using strain gauges. Temperature interferes with this chain at several points simultaneously.
The measuring body itself changes. As the temperature rises, the modulus of elasticity of the steel decreases, meaning the component deforms more under the same load. Without countermeasures, this shifts the characteristic value.
Zero point and characteristic value drift. Therefore, every transducer is temperature-compensated, typically from -40 to +80 °C as standard. Outside this range, the specified accuracy no longer applies, even if the sensor is still mechanically sound.
Application and materials reach their limits. Adhesives and carrier materials for strain gauges, potting compounds, seals, and cable insulation each have their own temperature limits. Frequently, it is not the steel that is the problem, but the cable.
The electronics can handle the least. Integrated amplifiers usually reach their limit well before the mechanical part.
Our high-temperature transducers up to 250 °C
For operating temperatures above the standard, we adapt the entire chain:
- High-temperature-compatible strain gauge application with heat-curing adhesives, performed in-house. More on this under strain gauge application.
- Extended temperature compensation, tuned to the actual area of use rather than the standard range.
- Hermetic encapsulation via laser or micro-plasma welding, so that neither moisture nor process media can enter the measuring body.
- PTFE connecting cables, resistant to continuous temperature and chemicals.
- Remote electronics. The amplifier stays outside the hot zone; the transducer remains passive. At 250 °C, this is the only sensible solution because no amplifier electronics can permanently withstand this temperature.
- Adapted material selection for measuring bodies, seals, and connecting parts.
This is implemented as a custom force transducer or as a force measuring pin in an adapted design. You can find the standard models that we start from under load cells and force transducers.
When it is hotter than 250 °C
Then the solution lies in the design, not the sensor. A transducer does not have to be located where the heat is generated.
Decouple heat. An intermediate piece made of poorly conducting material or simply more distance in the force flow significantly lowers the temperature at the sensor without falsifying the measurement. We manufacture suitable spacers and adapter pieces directly via our CNC machining services.
Shield radiation. Near a furnace, a large part of the heat input comes from radiation. A simple sheet metal shield between the heat source and the sensor often does more than any material upgrade.
Relocate the measuring point. Sometimes the same force can be captured at a cooler point in the force flow. We will check this with you before a complex high-temperature solution is designed.
Active cooling. Water or air cooling at the installation site is effective, but it is implemented on-site. We take this into account when designing the transducer and the connection situation.
What heat costs in terms of accuracy
Two points you should plan for.
Gradients are worse than absolute temperature. A uniformly warm transducer is easy to compensate for. A transducer that is hot on one side and cool on the other creates a deformation that cannot be distinguished from the load.
Thermal inertia takes time. After startup, the zero point drifts until the assembly has warmed through. For weighing tasks with high requirements, a warm-up time or regular zeroing should therefore be part of the concept.
Calibration is best carried out in a simulated installation situation, upon request according to ISO 17025 in our own laboratory.
Temperature sensor technology up to 1,200 °C
If the temperature itself needs to be recorded, our program goes significantly higher than for force measurement:
- Screw-in sensors with resistance thermometers or thermocouples, directly in the process. Depending on the type and design, thermocouples cover ranges up to 1,200 °C.
- Infrared sensors for non-contact measurement, suitable for moving parts, aggressive media, and places where no probe can reach.
- Magnetic surface sensors for retrofitting on pipes and containers without interfering with the process.
- Temperature transmitters with integrated electronics, HART, display, and limit contacts.
Which combination of probe, protection tube, and installation fits depends on the medium, response time, and accessibility. You can find an overview under temperature sensors.
Typical applications
Foundries and steel mills, forging and press hardening plants, furnace and dryer construction, glass industry, extrusion and injection molding, baking ovens and food production, test benches with thermal stress. We also handle test bench construction for complete assemblies.
What we need for a design
- Measured variable: force, load, weight, or temperature
- Temperature at the measuring point, continuous or as a peak, and whether it fluctuates
- Whether the transducer heats up evenly or on one side
- Nominal force and force direction; if temperature-related, the measuring range
- Installation situation, available space, and accessibility
- Desired output signal and distance to the evaluation unit
- Whether distance, shielding, or cooling can be implemented structurally
A sketch of the installation point with temperature details is sufficient for an initial assessment.