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Bolt Clamping Force | Bolt Torque to Clamping Force

What is Bolt Clamping Force?

Bolt clamping force refers to the force that is exerted on a bolt or fastener to hold two or more objects together. This force is the compressive load on the joint members that results from the tensile force developed in a tightened bolt. In simple terms, the bolt clamp force is what holds a bolted joint together, preventing them from separating. This force is critical to the safety and stability of many structures and machines, including bridges, buildings, and vehicles.

Why is it important to measure the Bolt Clamping Force?
By measuring the clamp force one can be sure that proper preloading forces were exerted to the bolted joint so that it will be better able to support varying service loads. Inaccurate or insufficient clamping force can result in structural failures, which can lead to catastrophic consequences. For example, if a bolt in a bridge or building is not tightened sufficiently, the structure can collapse, causing severe damage and loss of life.

Measuring the clamping force of a bolt also allows for proper maintenance and repair of machines and structures. Over time, bolts can loosen or stretch, causing the clamping force to decrease. Regular measurements of the bolt clamping force can alert engineers and maintenance personnel to potential issues and help prevent failures.

How Load Cells can be used in this application?
There are various factors to consider when applying load cell sensors to measure the clamping force of a bolt. First, the load cell must be properly assembled in the fixturing elements to ensure accurate measurements. The load cell must be mounted in a way that ensures it is not subject to external forces or vibrations that could affect the bolt load measurement. This requires proper load cell geometry specification that matches the bolt and nut mechanical requirements. Additionally, the load cell must be mounted to allow easy access to the bolt or fastener being measured for future maintenance and replacement.

Second, the load cell must be properly calibrated to ensure accurate measurements. Calibration is typically done using a known weight or force, and the load cell output is adjusted to match the known value. FUTEK offers an accredited A2LA load and torque calibration lab to ensure our products are shipped with proper calibration.

Last but not least, it is important to consider the effects of thread friction and underhead friction when using load cells to measure a bolt's clamping force. These friction forces can significantly affect the accuracy of the bolt load measurement and must be properly accounted for when interpreting the load cell output.


FUTEK's Donut/Thru Hole Load Cells are major players when measuring the tightening of the load directly. Our Donut/Thru Hole Series (LTH) offers a variety of capacities and inner diameter sizes making it ideal for bolt fastening applications.

Why is it important to measure the clamping force in metal die-casting applications?

Die Casting clamping force is the force applied to a mold by the clamping unit of the die-casting machine. Using load cells to measure mold clamping forces is critical for three reasons:

  • It helps ensure that the mold remains closed during the casting process, preventing any molten metal from escaping and causing safety hazards or defective parts. The clamping force also ensures that the mold halves remain aligned, preventing any warpage or distortion of the final product;
  • It helps identify any issues with the mold or machine that could affect the casting process. For example, if the clamping force is not sufficient, it may indicate that the mold is worn or damaged, or that the machine needs maintenance or repair.
  • Proper mold clamping force is necessary to achieve consistent casting quality and reduce scrap rates. If the force is too low, it may result in flash, where molten metal seeps out between the mold halves, or cold shuts, where the metal solidifies before filling the mold cavity completely. Both of these defects can result in scrapped parts and increased production costs.

How it Works
  1. FUTEK’s LTH Series offers several miniature load cells appropriate for this form of force measurement and testing.

  2. In the above application, FUTEK's LTH series load cell is installed between the bolt head and the nut, where it can measure the load as torque is applied. This is one of the best methods on how to how to measure clamping force.

  3. Our engineers recommend including a hardened washer between the load cell and the nut to avoid high friction and maintain flatness on the Thru-Hole during tightening and untightening.

  4. As the operator begins to fasten the bolt, the load cell will measure the bolt clamping load applied.

  5. This data can be monitored throughout testing via FUTEK’s IPM650 Panel Mount Display or IHH500 Intelligent Digital Hand Held Display; or it can be streamed to a computer via FUTEK’s USB Solutions.

  6. Operators and engineers can then review this data to verify whether or not they have reached the desired tension or clamp force on the fastener, stud or bolt via SENSIT™ Test and Measurement Software.

  7. FUTEK created an online bolt torque calculator to better assist you.

  8. Overall, the benefits of installing Thru Hole type load cells into your assembly process include: avoiding damage to bearing surfaces, decreasedproblematic tightening of large bolts, ease in untightening, and simultaneous tightening improvements. Still curious on how to measure bolt clamping force? You can read more in our white paper on bolt preload auditing.

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What is Bolt Clamping Force?

Bolt clamping force refers to the force that is exerted on a bolt or fastener to hold two or more objects together. This force is the compressive load on the joint members that results from the tensile force developed in a tightened bolt. In simple terms, the bolt clamp force is what holds a bolted joint together, preventing them from separating. This force is critical to the safety and stability of many structures and machines, including bridges, buildings, and vehicles.

Why is it important to measure the Bolt Clamping Force?
By measuring the clamp force one can be sure that proper preloading forces were exerted to the bolted joint so that it will be better able to support varying service loads. Inaccurate or insufficient clamping force can result in structural failures, which can lead to catastrophic consequences. For example, if a bolt in a bridge or building is not tightened sufficiently, the structure can collapse, causing severe damage and loss of life.

Measuring the clamping force of a bolt also allows for proper maintenance and repair of machines and structures. Over time, bolts can loosen or stretch, causing the clamping force to decrease. Regular measurements of the bolt clamping force can alert engineers and maintenance personnel to potential issues and help prevent failures.

How Load Cells can be used in this application?
There are various factors to consider when applying load cell sensors to measure the clamping force of a bolt. First, the load cell must be properly assembled in the fixturing elements to ensure accurate measurements. The load cell must be mounted in a way that ensures it is not subject to external forces or vibrations that could affect the bolt load measurement. This requires proper load cell geometry specification that matches the bolt and nut mechanical requirements. Additionally, the load cell must be mounted to allow easy access to the bolt or fastener being measured for future maintenance and replacement.

Second, the load cell must be properly calibrated to ensure accurate measurements. Calibration is typically done using a known weight or force, and the load cell output is adjusted to match the known value. FUTEK offers an accredited A2LA load and torque calibration lab to ensure our products are shipped with proper calibration.

Last but not least, it is important to consider the effects of thread friction and underhead friction when using load cells to measure a bolt's clamping force. These friction forces can significantly affect the accuracy of the bolt load measurement and must be properly accounted for when interpreting the load cell output.


FUTEK's Donut/Thru Hole Load Cells are major players when measuring the tightening of the load directly. Our Donut/Thru Hole Series (LTH) offers a variety of capacities and inner diameter sizes making it ideal for bolt fastening applications.

Why is it important to measure the clamping force in metal die-casting applications?

Die Casting clamping force is the force applied to a mold by the clamping unit of the die-casting machine. Using load cells to measure mold clamping forces is critical for three reasons:

  • It helps ensure that the mold remains closed during the casting process, preventing any molten metal from escaping and causing safety hazards or defective parts. The clamping force also ensures that the mold halves remain aligned, preventing any warpage or distortion of the final product;
  • It helps identify any issues with the mold or machine that could affect the casting process. For example, if the clamping force is not sufficient, it may indicate that the mold is worn or damaged, or that the machine needs maintenance or repair.
  • Proper mold clamping force is necessary to achieve consistent casting quality and reduce scrap rates. If the force is too low, it may result in flash, where molten metal seeps out between the mold halves, or cold shuts, where the metal solidifies before filling the mold cavity completely. Both of these defects can result in scrapped parts and increased production costs.

Bolt Clamping Force clamping force of a bolt bolt clamp load screw torque bolt load measurement
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Multi Axis Sensor, Force, Torqueapplications Bolt-Clamping-Force
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Z540-1 ANSI Certified17025 ISO Certified9001 ISO Certified13485 ISO CertifiedU.S. Manufacturer
+
Please follow us on linked inPlease follow us on twitterPlease follow us on youtubePlease Email us for additional info
+
10 Thomas, Irvine,
CA 92618 USA
All other trademarks, service marks and logos used in this website are the property of their respective owners.
© 1998–2024 FUTEK Advanced Sensor Technology, Inc. All rights reserved.