A flat metal strip is punched into circular disks.
The disks are formed into small cups. Then, these cups are degreased in a modern washing bay and annealed in a vacuum furnace.
A series of long draws transforms the cup into a seamless, closed-end tube of the highest quality.
While in the forming die, 1500psi of water pressurizes the inside of the tube as it is compressed, creating the corrugations.
The bellows are trimmed to size.
A final compression stage sets the bellows and gives it spring-like characteristics.