Custom torque sensors on short lead times

Peter Lewis, Managing Director at Applied Measurements, explains: "Many manufactured products require fatigue testing to ensure that they can operate for a guaranteed minimum period of time. An accelerated life test, for example, may be carried out on a drive shaft to determine the torque limits. The fatigue testing can sometimes be an afterthought. If this is the case, some kind of customised sensor is then required before the torque sensor can be coupled to the test unit. This is what Applied Measurements specialises in."

While Lewis concedes that there are plenty of companies able and willing to supply static (reaction) torque sensors from their standard range, many do not offer customised designs, let alone with lead times that are similar to standard products.

Mounting options

Applied Measurements manufactures two types of static torque sensor as standard, a square drive-mounting type and a flange-mounted unit. The DTD-S square drive-mounting sensor is designed specifically for measuring direct torque and is suitable for use in the calibration or testing of torque tools (screwdrivers or wrenches, for example) in quality assurance and inspection environments. The sensor is constructed from stainless steel and is protected to IP65. For fast, easy connection the sensor is supplied with an integral, robust bayonet lock military connector. The DTD-S is available from 10Nm up to 50,000Nm as standard, with custom versions rated to 200,000Nm.

The DTD-F flange-mounting static torque sensors are also designed to measure direct torque, but are suited to fatigue test applications. Again, the units are manufactured from stainless steel and are protected to IP65. The sensor is provided with an integral, robust bayonet Lemo connector for fast, easy connection.

Lewis adds: "The flange-mounting sensors are normally used in applications where there are two mating faces, one driving or applying the torque and the other resisting the torque. For any torque sensor to work, there has to be a reaction or load to generate the resistance to motion and hence torque.

"While we offer customers a range of standard torque sensors, we also have the ability to design and manufacture custom versions, where the standard unit does not suit the application. It could be the size and shape of the sensor that needs changing, but could also include the need for odd size ranges that fall between the standard increments."

Lewis says this could include making the sensor longer, shorter, broader, or with different flange diameters and thicknesses. Units with different hole spacings or with an odd size of square drive may be requested. As an alternative to the square drive unit, Applied has also designed round shaft units with keyways. By creating a tubular design and applying the strain gauges internally, it is possible to create high-integrity sealed units for use in wet environments. Other designs have included two-axis measurement of combined force and torque, pressure-compensated models and fully submersible units.

Applied Measurements has supplied custom static torque sensors to a variety of customers and industry sectors, including aerospace, marine, oil and gas, robotics, machine building and plastic moulding machines.

For more information about Applied Measurements' range of static torque sensors, call the sales department on +44 (0)118 981 7339, email [email protected] or go to the website.