Bonding with hot glue

Bonding is the connection of parts to be adherend using an adhesive.

An adhesive is a non-metallic material that can connect two parts to be joined by means of adhesion (=surface adhesion) and cohesion (= internal strength).

In order to be able to glue with hot-melt adhesives, these must first be melted. The hot adhesive can either be applied only to the surface of one of the adherends or to the surfaces of both substrates.

There, the hot-melt adhesive immediately begins to cool down and the viscosity increases.  After the application, the substrates must be joined together within a certain period of time (open time), during which a contact pressure must be exerted so that the adhesive also wets the second substrate.  

By cooling below the solidification temperature, a permanent bond between the substrates is achieved.   

The working principle of the hot-melt adhesives consists of a double change of the physical state.