The main difference between tubular and semi-tubular rivets lies in the depth of their hollow portion. Tubular rivets have a shank hole depth that is at least 112% of the shank diameter, while semi-tubular rivets have a shank hole depth of less than 112% of the shank diameter. Both types are used to join materials together, but the deeper hollow in tubular rivets may offer advantages in specific applications.

Tubular Rivets:
Also known as hollow rivets, tubular rivets have a fully hollow shank or tail. They are typically used in applications where a pivot point or movement is needed, or when joining thin materials like plastics, leather, and sheet metal. The hollow portion allows the rivet to expand and create a secure hold when installed, often with a hammer and tool.

Semi-Tubular Rivets:
Semi-tubular rivets have a partial or shallower hollow shank compared to tubular rivets. This shallower hollow can reduce the amount of force needed for installation, and the rivet can be used to create a secure, permanent joint. They are often used in applications where a pivot point is not required but a secure, permanent connection is needed.

Installation:
Both types of rivets require an anvil or tool to bend or spread the shank outwards to create a permanent, secure joint.