Manufacturing Edge Welded Bellows – the Basics
The process for manufacturing edge welded metal bellows begins with hydraulically stamping strips of metal sheets into diaphragms. Once stamped, diaphragms are inspected for quality and cleaned to ensure that the material is free of any grease or dirt. Next, the diaphragms are positioned back-to-back (male to female) to pair the inside diameter holes. They are then welded together through plasma, laser, arc, or electron beam welding equipment depending on the manufacturer and material. Vision systems can aid the accuracy and consistency of welds. The entire process is continued in order to make the proper number of convolutions. Once the inside diameter welds are completed, the convolutions are prepared for outside diameter welding. Depending on the welding equipment, chill rings are inserted between the convolutions in order to ensure that the heat from the welds does not distort or change material properties in the adjacent material.
The finished product is a long flexible assembly. The design of the metal diaphragms gives the bellows assembly its dynamic flexibility and high – performance characteristics.
Most customers require end plates or custom flanges to meet a specific requirement or application and these end pieces can be welded to the end of each side of the bellows for a finished assembly.
Key Bellows Design Factors
The pressure, stroke length, spring rate and temperature help to determine the thickness and material required to meet the applications’ demands.
The shape of the ripples and inside and outside edges of the diaphragm are crucial to the performance of the bellows assembly.
The ripples need consistency between diaphragms to survive high cycles and create accurate spring rates.
The weld shape and penetration are critical to edge welded bellows design.
What about Pressure and Temperature?
The differential pressure between the inside and outside of the bellows is critical. The details regarding how the bellows is used in the application also help to design it to ensure proper function and cycle life. Axial and lateral offsets can also change the pressure capabilities of the bellows assembly.
BellowsTech engineers and sales support staff understand the dynamic principles and relationships between vacuum and positive pressure movement, internal and external pressures and how these variables can change the diameter, length and stroke parameters.
Temperature is easier to define. Once the ambient and environmental temperatures are understood, the correct material is selected.
Why BellowsTech Edge Welded Bellows
Although most manufacturers follow the basic principles of edge welded bellows manufacturing, BellowsTech understands the unique qualities and exceptional performance characteristics that go into producing a superior product, therefore, we practice a more stringent manufacturing process to the most exacting standards.
- Over fifty years of design and manufacturing experience
- Proprietary stamping, cleaning and welding techniques for exceptional strength and consistency
- Individually inspecting diaphragms for the highest quality to ensure welds are the strongest and leak-tight
- Special handling to protect against contamination of the materials
- Deep penetrations and consistent weld bead geometry to ensure a leak-tight joint that can withstand high cycle applications
- Engineered for optimal performance with an internal vacuum or external pressure
- Optional heat treating to strengthen the material
- Helium leak testing to industry standards (1×10-9 for stainless steel material) to ensure the assembly is completely sealed.
- Lower leak rates are available as required
- Over 90 standard sizes, round and non-round shapes
- ISO 9001:2008 certified
- Quality Assurance Certificate