Torque-Thrust Sensors for Specialty Applications

Industry Insights

Torque-Thrust Sensors for Specialty Applications

The use of specialty industrial applications often requires creativity when it comes to measuring the forces involved in the application. One example of this is with friction stir spot welding (FSSW). This is a type of welding where two “parent” materials with low melting points are acted upon by a rotating tool that plastically deforms and forges the two parent materials together.

The rotating FSSW tool consists of a shoulder and pin which is plunged into a workpiece and then moved along the intended weld seam. The pin plastically deforms the parent materials and forges them together under the shoulder. The axial force that results in the forging pressure has to do with rotation speed, traverse speed, and how deeply the tool is plunged into the workpiece. FSSW can save energy and costs compared to electric resistance spot welding in many cases.

This type of welding is particularly important in the aircraft and automotive industries due to interest in joining lightweight alloys. Advantages of FSSW include low heat input and relatively low maximum temperatures, lack of toxic fumes, excellent bonding, and a process that can be automated. The technique has tremendous potential in manufacturing, where it can replace many traditional joining techniques.

Why Torque Measurements Are Essential to Industrial Processes

Force control is essential in FSSW applications. This type of welding requires a large axial force to be maintained on the joining tool, and without force control, robotic FSSW processes are prone to welding flaws as the robot repositions linkages to move along the intended weld seam. Companies developing FSSW applications are interested in measuring torque so that processes can have consistent, desired outcomes with repeatable quality.

Torque sensors along with electronic components are used to measure torque with FSSW. In these sensors, strain gage technology is used to produce an electrical signal proportional to measured torque so that torque can be monitored. But sometimes conventional dynamometers are not appropriate for the torque measurements required for a particular industrial application. Rotating dynamometers, for example, may not have sufficient stiffness for an FSSW application. In these cases custom torque-thrust sensors may be designed.

Custom torque sensors are sometimes required in development of new manufacturing techniques.

Custom Torque-Thrust Sensors

Friction stir spot welding may have great potential to replace other single-point joining processes like riveting, but measuring torque in these applications can be tricky with conventional dynamometers. In these cases, the customer may need a custom torque-thrust sensor. The customer may or may not want other forces (like axial force) to be measured. Builders of custom torque-thrust sensors (like Sensing Systems) allow manufacturing developers to test techniques like FSSW in their new applications even when off-the-shelf dynamometers are not sufficient to make the measurements they need.

Accuracy of Torque-Thrust Sensor Measurements

Accuracy of torque-thrust sensor measurements is paramount. Sensing elements must be chosen depending on the application, and they are scaled up or down to accommodate the capacity a customer requires. Sensing elements on custom torque-thrust sensors sometimes must be incorporated into unique mechanical packages, and must be protected to withstand environmental conditions of the user’s application. Outside geometry may need to be machined to any number of geometric shapes for a customer’s requirements. What’s more, all sensors must be calibrated using NIST-traceable standards. Finally, sensors must communicate with instrumentation or data acquisition systems so users can monitor torque-thrust measurements easily.

Delivery of Custom Devices Doesn’t Have to Take a Long Time

The key to acquiring custom torque-thrust sensors in a timely manner is working with a provider that fully understands “custom off-the-shelf” sensors. With an extensive library of existing designs covering all capacities and configurations, providers like Sensing Systems are able to turn machine parts into sensors by adding measurement capability, modifying existing parts or manufacturing new parts as needed. What this means for customers is highly accurate, calibrated torque-thrust measurement from a sensor designed specifically for their needs, like the need to measure torque in FSSW applications.

Whether you need load cells, torque sensors, instrumentation, or calibration kits, Sensing Systems can provide you with an off-the-shelf or custom measuring device that perfectly meets your needs, with the efficiency of custom-off-the-shelf production. If you need help finding the perfect measurement technology for FSSW or another application, please feel free to contact one of our qualified specialists. We would be more than happy to speak with you and answer any questions you may have.

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