Which rivet head types are the most commonly used?

The most commonly used rivet head types are the universal and 100 degree countersunk heads. The universal head rivet is preferred for its versatility and ease of use, as it can be applied in various positions and is less prone to the leaking of fluids due to its design, which allows for some surface irregularities. The 100 degree countersunk head rivet is utilized primarily in applications where a flush finish is required, ensuring aerodynamic efficiency and aesthetic smoothness on the surface of aircraft.

In practice, these two types of rivet heads serve significant roles in both structural integrity and surface treatment on aircraft, making them the standard choices in metal structural repair and assembly. Other rivet heads, while they may have specific applications, do not match the overall utility and functionality provided by the combination of universal and 100 degree countersunk head types.