Torque to Turn

Torque to turn testing is a method used to determine the rotational resistance in mechanical components and assemblies. It measures the torque required to either initiate movement from a stationary position, known as breakaway torque, or to maintain rotation once movement has started, referred to as running torque.

Unlike closure or fastener torque measurement, which focuses on tightening forces, torque to turn testing is concerned with frictional resistance, alignment, lubrication, material deformation and other mechanical factors affecting rotational performance.

Breakaway torque reflects the point at which static friction is overcome. Running torque assesses the energy required to keep a component moving at a set speed. By measuring both, engineers gain a complete picture of how an assembly will behave under real-world operating conditions.

Torque to turn testing plays a critical role in evaluating the performance, reliability and quality of rotating components. It can identify sources of excess resistance, such as poor lubrication, misalignment or surface damage, verify that components meet design specifications before deployment, and detect inconsistencies in manufacturing processes that could lead to premature wear or failure.

In industries such as automotive, aerospace, medical device manufacturing and industrial machinery, even small deviations in torque behaviour can impact product safety, user experience and operational efficiency. Systematic torque to turn measurement helps engineers validate designs, prevent defects and maintain compliance with performance expectations.

For example, in an automotive steering assembly, excessive breakaway torque could indicate misaligned bearings, while insufficient running torque in a medical device mechanism could suggest inadequate engagement between mating parts.

Torque to turn testing typically involves mounting the test specimen in a secure fixture, aligning the axis of rotation, and applying torque until the component begins to move.

For breakaway torque measurement, force is applied slowly until the first point of motion is detected. Running torque is then measured at a constant rotational speed, ensuring smooth movement without acceleration spikes.

Key considerations include:

• Fixture alignment - Misalignment can introduce additional resistance and skew results.
• Speed control - Consistent rotational speed is essential for accurate running torque readings.
• Angular rotation measurement - Recording torque alongside angular displacement provides deeper insight into component behaviour across the motion range.
• Manual or motorised systems - Manual testing may suit low-volume or low-precision needs, whereas motorised programmable testers deliver repeatability, controlled speed ramps and automated data capture.

Mecmesin offers a range of precision torque test systems, including the OmniTest and MultiTest-dV series, capable of capturing both breakaway and running torque with high resolution and accuracy. These systems detect subtle changes in resistance, making them ideal for applications where consistent performance is essential.

For complex requirements, programmable motorised torque testers, powered by VectorPro software, allow engineers to define precise test profiles. These can include variable speed ramps, dwell times and multi-stage torque applications. The software enables storage and recall of test methods, ensuring repeatability across operators and locations.

Advanced torque to turn systems can record torque against angular rotation, producing torque-angle curves. These reveal behaviours such as chatter, slip, peak torque and steady-state torque, offering valuable diagnostic data beyond a single torque reading.

Mecmesin torque to turn systems are used in sectors including:

• Automotive steering and drivetrain component testing
• Aerospace actuator and control surface evaluation
• Medical device verification for rotating mechanisms such as surgical tools
• Testing industrial controls, valves and rotating assemblies
• Spring testing where torque and angular displacement are critical

Alongside equipment supply, Mecmesin provides consultation, custom fixture design, installation, operator training and ongoing calibration services. Regular calibration against traceable standards ensures that measurement systems remain accurate, reliable and compliant with industry requirements.

There is no single universal standard for all torque to turn testing, but the method aligns with several sector-specific standards. Examples include:

• ASTM D7860-14 - Standard test methods for measurement of torque retention in continuous thread closures using automated torque testing equipment
• EN ISO 13127 - Test method for child-resistant packaging mechanical performance

Compliance typically involves documenting test methods, calibrating devices to traceable standards and maintaining a full record of results.

What is the difference between breakaway and running torque?

Breakaway torque measures the force required to start movement by overcoming static friction. Running torque measures the force needed to maintain motion once it has begun.

How important is fixture alignment?

Incorrect alignment introduces unwanted resistance, leading to inaccurate readings. Precision alignment is critical for meaningful results.

Are manual torque testers suitable for torque to turn?

Manual testers can be used for low-precision or simple applications, but automated systems offer better repeatability, speed control and data logging.

How is calibration maintained?

Calibration should be performed regularly against traceable standards. Many organisations arrange service agreements to ensure accuracy is maintained.

For engineers looking to define robust torque to turn test protocols or specify equipment, Mecmesin’s applications engineering team offers specialist guidance. From fixture design to full system integration, the team can configure solutions that meet both technical requirements and industry standards.