The pre tightening force of a bolt is the pre tightening force generated along the axis of the bolt between the bolt and the connected part under the action of tightening torque during the process of tightening the bolt. The measurement of bolt pre tightening force provides reliable basis for production safety, equipment operation and maintenance. Pre tightening force sensors and warning bolts can directly output the tensile or compressive force received by the bolt, making the measurement more accurate and the data more reliable. At the same time, we can provide different forms of bolt warning force measurement schemes according to different working conditions. Widely used in various fields such as automobile manufacturing, heavy industry, maritime aviation, aerospace, military industry, wind power mining, production and research institutions.