From a metal-strip to a seamless metal bellow


Metal bellows made by Mera Bellows are manufactured by a multistage plastic deformation process, starting with a metal strip. We receive high precision, thin-walled tubes as an intermediate product and at the request of our customers, we have included them in our product range.


Manufacturing Tubes

A multi-stage press cuts round plates out of a metal strip and forms them into small cups. These are cleaned and degreased using eco-friendly paraffin and later vacuum annealed. Following this, the cups are deep-drawn in several steps into thin-walled tubes. Concluding the processes, the tubes are once again cleaned and annealed using vacuum or inert-gas. This is the technique that Mera Bellows uses to manufacture high-precision tubes with closed ends. If requested, the ends can be cut in order to supply open tube constructions.



Producing Bellows

The hydroforming of a bellow is done inside of a purpose-built, very complex tool. To form the convolutions, water is pressed inside the tubes with a pressure of up to 250 bar. At the same time the tool is compressed. After hydroforming, the neck of the bellow is cut to the correct length, the shape of the bottom is formed, and the bellow gets its final length. Afterwards the metal bellows are cleaned once again and then stress-relieved under an inert-gas protection.