Tube bending is the umbrella term for metal forming processes used to permanently form pipes or tubing. One must differentiate between form-bound and free form-bending procedures, as well as between heat supported and cold forming procedures.
Press bending is probably the first bending process used on cold pipes and tubing
Rotary draw bending:
Full tooling for rotary draw bending
Rotary draw bending (RDB) is a precise technology, since it bends using tooling or "die sets" which have a constant center line radius (CLR), alternatively indicated as mean bending radius (Rm).
Main article: Roll bending
During the roll bending process the pipe, extrusion, or solid is passed through a series of rollers (typically three) that apply pressure to the pipe gradually changing the bend radius in the pipe.