Enter your Bolt Diameter, Bolt Material, Thread Type, and Axial Bolt Force, then adjust the K Factor, Surface Condition, and Lubrication Reduction to calculate your Required Torque — plus a safe operating range (Min/Max Torque) and the resulting Clamp Force holding everything together.
Required Torque
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Min Torque (-25%)
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Max Torque (+25%)
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Clamp Force
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The K factor is a torque coefficient that accounts for friction between the bolt and the mating surface. It varies based on surface finish, coatings, and lubrication, typically ranging from 0.16 to 0.30.
Lubrication reduces the friction coefficient, which means less torque is needed to achieve the same clamping force. Lubricated bolts typically have a K factor of 0.18 compared to 0.20 for dry steel.
Coarse threads have fewer threads per inch and are stronger in tensile applications. Fine threads provide better adjustment precision and are less likely to loosen due to vibration.
Torque wrenches typically have an accuracy of ±25%, and material properties can vary. The range accounts for these uncertainties while ensuring proper bolt preload.
Axial force is the tensile load applied along the bolt axis. For standard installations, use 0. For specific applications, calculate based on the actual loads your joint will experience.
Overtightening can cause bolt failure, thread stripping, or permanent deformation. It may also reduce the bolt's fatigue life and compromise the joint's integrity.
Yes, higher grade bolts (like Grade 8) can handle more torque than lower grades (like Grade 2). Always match the torque specification to the bolt grade and application requirements.