* Bolt grade: This indicates the bolt's tensile strength. Higher-grade bolts (e.g., 8.8, 10.9, 12.9) require significantly more torque than lower-grade bolts. The grade is usually stamped on the bolt head.
* Bolt material: Different materials have different yield strengths.
* Thread type: Coarse or fine threads affect clamping force.
* Lubrication: Lubricated bolts require less torque to achieve the same clamping force.
* Application: The intended use significantly impacts the required clamping force and therefore the torque. A bolt holding a car engine in place needs far more torque than one holding a shelf bracket.
To find the correct torque, you need to consult:
1. The manufacturer's specifications: If the bolt is part of an assembly (like a car engine or a specific piece of equipment), the manufacturer's service manual will specify the correct torque. This is the most reliable source.
2. A torque specification chart: These charts list recommended torque values for various bolt sizes, grades, and materials. You can find these online or in engineering handbooks. However, always prioritize the manufacturer's specifications if available.
3. A torque wrench: This tool is essential for applying the correct torque. It's far better than relying on "feel" to tighten a bolt.
Without knowing the specific bolt grade and application, any torque value given here would be a dangerous guess. Using the wrong torque can lead to stripped threads, broken bolts, or insufficient clamping force, resulting in failure of the assembly. Always prioritize safety and consult the appropriate documentation.
