A rivet is a short cylindrical bar with head integral to it. The cylindrical portion of the rivet is called shank or body and lower portion of shank is known as tail. The rivets are used for permanent fastening. The riveted joints are widely used for joining light metals. The function of rivets in a joint is to make a connection that has strength and tightness. The strength is necessary to prevent failure of the joint. The tightness is necessary in order to contribute to strength and to prevent leakage as in a boiler. When two plates are to be fastened together by a rivet, the holes in the plates are punched and reamed or drilled.
Punching is the cheapest method and is used for relatively thin plates and in structural work. Since punching injures the material around the hole, therefore drilling is used in most pressure vessel work.
Diameter of rivet hole (d h) = diameter of rivet (dr) + 1.5 mm
The plates are drilled together and then separated to remove any burrs or chips. When a cold rivet is used, the process is known as cold riveting and when a hot rivet is used the process is known as hot riveting.
The cold riveting process is used for structural joint while hot riveting is used to make leak proof joints. In case of long rivets, only tail is heated and not the whole shank.
