To meet the most exact specifications of our customers, we produce a wide range of hydroformed metal bellows.
They are key components in a large number of applications and thus manufactured with utmost care and reliability.
Designing of metal bellows
The design is a challenge for metal bellows manufacturers. Usually a low wall-thickness is needed in order to meet flexibility requirements. Therefore, metal bellows are often thinner than all other parts of the system in which they are implemented. Different types of corrosion may occur in sometimes extreme environments.
- surrounding media (gas or liquid) to which the internal and external bellows surfaces will be exposed
- Working stroke/maximum stroke (axial compression or extension that the metal bellows have to perform)
- Vibration characteristics
- Occurring temperatures
- Working pressure/pressure peaks
- Spring rate
- Mean-effective area
- Lifecycle expectancy
Based on this, the geometric parameters have to be selected:
length (total and corrugated length)
Inside & outside diameter of convolutions
wall-thickness (one or two-ply design)
diameter of the neck & specifications of the bellows endings
Manufacturing of formed seamless metal bellows
The production starts with a metal-strip that is cut into blanks using a hydraulic press. They are deep-drawn into thin-walled tubes with closed ends in several steps. The hydroforming process works with water pressure which is defined depending on the diameter and wall-thickness. Simultaneously, a customized cassette is being moved in the axial direction of the metal tubes, which leads to an even formation of convolutions that gives the metal bellows their well-known shape. Afterwards, they are cut to the desired length, cleaned using eco-friendly paraffin and stress-relieved. A final compression operation in the direction of the axis – can create an omega profile that (at a specified length) allows more convolutions than a sinus-shaped profile. This enables the metallic bellows to compensate larger movements and also improves for some applications the efficiency of axial movement absorption by equalizing expansion stress. Special coatings are available on demand. Being a globally competitive metal bellows manufacturer, our large-scale production is based on Lean-Management.
Compared to bellows formed from seam-welded tubing (e.g. of stainless steel) the seamless designs show very tight tolerances, thus
convince with accurate spring rate and long life-cycle for high-precision applications.
Besides, this manufacturing method enables to supply precision bellows with one closed end. Many more designs are possible. The metal bellows with bottom are widely used in measuring and controlling applications as they can convert pressure into movement.
Application examples of metal bellows
- metallic hermetic seals that absorb axial movements: e.g. protecting valve stem from surrounding media (in bellows sealed valves)
- bellows- and metal bellows assemblies for pressure-, temperature- or altitude sensors (Aneroids)
- volume compensators for aerospace
- metal bellows couplings
- medium-voltage vacuum circuit breakers for energy distribution: The vacuum interrupter contains a stainless steel bellows that seals the high vacuum system while allowing movements of the contacts
- elastic bellows connectors, for instance in solar thermal systems: compensation of vibration, tension, and thermal expansion between the solar collectors. Our customized end solutions allow an easy and time-saving installation with O-rings and convenient plug-in system
About Mera Bellows:
1956: Established as a metal bellows manufacturer in Poland
2000: Acquisition by a German investor
2002: Entering the U.S. market
Since 2005: ISO9001 certified
Since 2007: New production site
Since 2009: ISO14001 certified
Every stage of the manufacturing process is monitored
long life expectancies for all our metal bellows
Plenty of test devices help to analyze consistency