Angle Monitoring: The Yin to the Torque Control Yang

Many manufacturers continue to use torque control technologies as the primary method to specify and control how they tighten threaded fasteners. However, torque measurement alone may be misleading.

Every fastener, hole dimension, material strength and lubrication condition differ, making each assembly a unique event. Manufacturers that rely on torque alone may not achieve the target clamp load and face potential rework or safety-critical errors.

A fastener behaves similarly to a stiff elastic band. The more a fastener stretches, the more force reacts to return the fastener to its original position. This ‘clamping’ force is what holds the joint components together and helps the assembly remain secure. It is vital that the ‘elastic’ fastener stretches enough to apply the proper clamp load but not so much that the joint components or fastener becomes damaged.

As a bolt rotates, it stretches and the joint compresses. The amount of angle rotation and the thread pitch of the fastener dictate the axial distance equivalent to the stretch and compression.

Angle monitoring can be the best indicator of proper tightening. The angle is proportional to the bolt stretch, which is directly related to clamping load. If manufacturers only measure torque, they may not take into account variability and wasted energy to overcome friction.

Tools with angle monitoring capabilities empower manufacturers to be more precise. The technology gives operators peace of mind that they are securing each fastener and joint with the appropriate clamp load.

Today, tools are available that have both torque and angle monitoring features in one package. Torque control and angle monitoring go hand in hand. Torque is the force that binds parts together within a specific friction range, and angle monitoring verifies that range. Thus, angle monitoring ensures the proper clamp load for quality throughput. Precision fastening tools, such as the  Direct Current (DC) and  QX Series lines from Ingersoll Rand®, equip manufacturers with both torque and angle capabilities.