What part of the fastener allows it to be installed and create pre-load pressure?

The pintail is an integral part of certain types of fasteners, particularly in the case of blind rivets and some high-strength structural bolts. Its primary function is to facilitate the installation of the fastener and help create the necessary pre-load pressure that ensures the fastened components are securely joined together.

During installation, the pintail is pulled, which draws the fastener into the material. As the pintail continues to be pulled, it expands the fastener (such as the rivet) against the material being joined, thus creating a tight fit. The resulting pre-load pressure is crucial because it helps to keep everything snug and prevents loosening due to vibrations or load changes.

Understanding the role of the pintail helps to appreciate how fasteners contribute to the integrity of aerospace structures, as achieving the right pre-load ensures that assemblies can withstand the high demands placed upon them in flight.