For decades the applications of sensors measuring torque and force changed rather little. In recent years new challenges arose which require new innovative solutions for sensors and large volumes in sensor production. Conventional torque sensors on the basis of strain gauges are still very useful for very precise measurements in test applications, for instance. However, they are very expensive and also their maintenance is very costly. This prevents their use in large numbers and they are therefore not suitable for the new requirements.

Apart from this the conventional technical solutions are not suitable for applications in industry 4.0, big data and serial smart products. There is a new technology that offers a solution to this issue which is suitable for serial production: non-contact torque sensors based on magnetostriction.

The technology behind non-contact measurement

The shaft itself is turned into the “transmitter” of a sensor by magnetic encoding in a magnetising process patented for NCTE.

Without touching the transmitter, the “receiver” senses the changes of the magnetic field at a distance of several millimetres – even through a layer of dirt and/or lubricant and at very high numbers of revolutions – and processes these changes. This magnetic field-technology uses the shaft as it is. There is no need to change its design. The receiver unit can be designed as required by the application and thus offers entirely new opportunities for defining measuring points and use cases. This magnetic technology is already used in many smart products like e-bikes, torque measurement in robotics or drive shafts in industry. The solution is both non-contact and compact and – compared with other measuring technologies – it is cheaper by a factor of up to 10.

NCTE’s measuring principle is based on the effect of inverse magnetostriction. This is based on the fact that an object’s magnetic field changes when it is subjected to mechanical forces. If an object is magnetised, this leads to a distortion of its crystal structure and thus to magnetostrictive deformation. Inversely this effect can be used by measuring the change of magnetisation induced in magnetised material by mechanical loads. Figure 1 shows a magnetised shaft with schematic field lines. When an external force is applied to the shaft (shown by the colour changes in the image) the orientation of the previously existing magnetisation changes. This effect is called inverse magnetostriction and it is the basis of NCTE’s measuring principle. The magnetic field is circular and after deformation or vibrations it always returns to its original shape and orientation.

NCTE sensors

NCTE’s non-contact standard sensors can be used everywhere without special adaptation, be it in test rigs or medical engineering products or highly complex industrial products. All sensors are “Made in Germany”. They are made at the company’s seat in Oberhaching near Munich. With short delivery times from stock the sensor systems are integrated in the applications as plug & play units. Accuracy is better than 0.1 % for rotational speeds of more than 10,000 rpm and nominal torques between 1 and 25,000 Nm.
www.ncte.com/en/standard-products

Apart from standard sensors NCTE develops tailor-made solutions for specific applications – from the initial idea to the design of the first prototype up to production. Because they are so economical non-contact magnetic field sensors are suitable for both single-piece and serial production. Tailor-made solutions by NCTE are used wherever parts are rotating. To date they are used in motor sport, in test rigs for automotive systems or in e-bike motors.
https://ncte.com/en/customised

NCTE-sensors are regularly tested under extreme conditions. Our non-contact sensors still deliver correct results after more than 2 million load cycles, 68 temperature cycles and 120 hours of vibration. Even 8 weeks of exposure to an eccentric load did not lead to a major distortion of the measuring results.

ATEX approval

As an option, NCTE offers the contactless torque sensors of 2000 series with approval for ATEX Zone II 3G Ex IC IIB T4 Gc according to the ATEX directives of the European Union.