Screw tightening torque

Bolt torque, often simply referred to as tightening torque, is the torque applied to a bolt or nut to tighten it. It is measured in Newton meters (Nm) or foot-pounds (ft-lb) and is critical to making secure connections in mechanical systems. A correct tightening torque ensures that the bolt builds up enough tension to hold the connected parts together without being overstressed.

Meaning of the screw tightening torque

The correct tightening of screws is crucial for the integrity of connections in mechanical engineering:

1. Avoiding over- and under-tightening: Correct tightening torque prevents screws from being tightened too loosely (under-tightening) or too tightly (over-tightening), which can lead to damage or failure.
2. Ensuring operational safety: Correct voltage ensures the reliability and safety of the connection, especially with dynamic or changing loads.
3. Extended service life: Optimum tightening torques contribute to the longevity of the screws and the connected parts by distributing the load evenly.

Calculation of the screw tightening torque

The calculation of the correct tightening torque depends on various factors, including the screw size, the material, the type of connection and the operating conditions. In general, the formula applies: M=K⋅F⋅d

where:

• M is the tightening torque,
• K is the coefficient of friction,
• F the preload force and
• d is the screw diameter.

Application of the screw tightening torque in mechanical engineering

The screw tightening torque is used in numerous areas of mechanical engineering:

1. Assembly of machines and systems: Ensuring the firm and reliable assembly of machine components.
2. Automotive industry: Used in the assembly of vehicle parts to ensure safety and performance.
3. Aerospace: Critical applications where the integrity of connections is vital.
4. Civil engineering: Fastening of structural elements and infrastructure projects.

Tools for measuring the screw tightening torque

Various tools are used to measure and check the tightening torque:

1. Torque wrench: Manual or electronic tools that precisely measure and control the tightening torque.
2. Torque wrenches: Electric or pneumatic tools for repeatable and controlled tightening torques.
3. Torque testers: Devices for calibrating and checking the accuracy of torque tools.