Breakloose Torque

Breakloose torque, also called breakout torque, is the amount of torque required to overcome the initial static friction or resistance when loosening or breaking free a fastener, such as a bolt or nut, that has been tightened or is stuck.  When a fastener is tightened, it creates a clamping force that holds the components together.  This clamping force creates friction between the threads of the fastener and the mating surfaces.  Breakloose torque is the torque needed to overcome this friction and initiate the motion required to loosen or unfasten the fastener.

Breakloose Torque Formula
\( \tau_p \;=\;  P \cdot  \dfrac{ \mu \cdot r + p  }{  2 \cdot \pi  } \)
Symbol	English	Metric
\( \tau_p \)  (Greek symbol tau) = Breakloose Torque	\(lbf-ft\)	\(N-m\)
\( P \) = Preeload Force (Axile Force)	\(lbf\)	\(N\)
\( \mu \)  (Greek symbol mu) = Friction Coefficient between the Threads and Under the Bolt Head/Nut	\(dimensionless\)	\(dimensionless\)
\( r \) = Effective Radius of the Thread or Bearing Surface	\(in\)	\(mm\)
\( p \) = Thread Pitch	\(in\)	\(mm\)
\( \pi \) = Pi	\(3.141 592 653 ...\)	\(3.141 592 653 ...\)

Breakloose torque can depend on various factors, including the type of fastener, the condition of the threads, the lubrication present, and the amount of force applied perpendicular to the fastener.  Additionally, factors such as rust, corrosion, or thread damage can increase the breakloose torque required.