Torque values are calculated with how much safety factor below the yield point?

Torque values are calculated with how much safety factor below the yield point?

• A. 10%
• B. 30%
• C. 20%
• D. 50%

Answer: (C)

Torque values are set with a safety cushion so that the stress in the component stays below the yield point, keeping the part in the elastic range and avoiding permanent deformation. Using a margin of about 20% below yield means the allowable stress is roughly 80% of the yield strength. This 20% cushion accounts for variations in material properties, manufacturing tolerances, temperature, and dynamic loading, providing reliable clamping without being overly conservative. If the margin were smaller, the design would be closer to yielding under normal variations and could risk permanent deformation or looseness; if the margin were larger, you’d unnecessarily limit the torque you can apply and reduce clamping force. Hence, 20% below yield is a practical, commonly used buffer.

Torque values are set with a safety cushion so that the stress in the component stays below the yield point, keeping the part in the elastic range and avoiding permanent deformation. Using a margin of about 20% below yield means the allowable stress is roughly 80% of the yield strength. This 20% cushion accounts for variations in material properties, manufacturing tolerances, temperature, and dynamic loading, providing reliable clamping without being overly conservative. If the margin were smaller, the design would be closer to yielding under normal variations and could risk permanent deformation or looseness; if the margin were larger, you’d unnecessarily limit the torque you can apply and reduce clamping force. Hence, 20% below yield is a practical, commonly used buffer.