Metal Bellows
Advantages of the Bellows
Unrivaled Cycle Life. M Series Bellows has achieved unrivaled life. The company guarantees that these bellows will achieve five million cycles at 100% of the rated stroke. Testing has demonstrated cycle life that greatly exceeds the five million-cycle goal. Special forming and welding techniques and years of experience have enabled the company to customize bellows that have demonstrated over 1.8 billion cycles.
Ultra Clean Bellows. Ultra-high vacuum/ultra-high purity bellows are fully electropolished inside and out for minimum outgassing and particle generation. They are suitable to vacuum levels of 10-10 torr (10-8 Pa) or better. Outgassing rates as low as 4 x 10-9 W/m2 [3x10-12 torr l/(sec cm2)].
Multiple Styles. The bellows are designed in a variety of styles to provide the flexibility, spring rates, and pressure capabilities required for the application. The company offers the advantage of providing both welded, formed and multi-ply bellows. Each has its own merits and the company will recommend to customers, the most efficient, cost-effective solution.
Full Assemblies. The company also offers the advantage of providing the necessary flanges, seals and valve elements to integrate the bellows into existing systems.
Design Excellence. The bellows have a proven record of accomplishment of over 30 years. Drawing on experience serving numerous industries, the company provides comprehensive assistance in every aspect of product development including; design, material selection, manufacturing and testing.
State of the Art Production Facilities. Welding capabilities include the latest GTAW, plasma, YAG laser and Electron Beam welding machines. Facilities include in-house clean-room environments up to class 100.
FEA. Utilizing the latest 2-D and 3-D finite-element and classical analysis, components are designed to give optimum performance and are engineered for superior dependability and reliability.
Testing and inspection includes:
- High cycle fatigue testing
- 100% leak test inspection with a mass spectrometer to 10-10 std. Cc/sec
- Microsection inspection
- Non-Destructive Testing (NDT)
ISO 9001 Certified. The quality system is certified to ISO 9001 to ensure customer satisfaction.
The Basics of a Bellows
A bellows is a compressible and extensible component providing an ultra leak tight connection while accommodating relative movement. It also shields the operating environment from particulate contamination by encapsulating moving mechanical components such as rotating shafts, linear actuators, and valve stems. This is critical in applications demanding exceptionally clean conditions such as ultra-high vacuum and semiconductor fabrication equipment.
An Advanced bellows is designed and manufactured to provide a unique combination of high strength and high flexibility. It must have the hoop strength to withstand high pressures as well as the longitudinal and angular flexibility to accommodate the required deflections or movements. Deflection of a metal bellows results in stresses. These deflections are frequently repetitive, thus the bellows must be designed to minimize these stresses in order to enable the bellows to endure the high cycle deflection and avoid premature fatigue failure.
To reduce the bending stresses, the wall thickness, or convolution thickness, can be reduced. To withstand the forces of high pressure, the thickness can be increased. Selecting the right thickness to achieve the delicate balance of thickness for pressure, thinness for reduced stress, long life and flexibility is the challenge faced by the bellows designer.
Welded Bellows
V Series and M Series bellows start with disks that are precision stamped from thin metal strip. Pairs of these disks are welded at their inside diameter. They are then stacked and welded together at their outside diameter. The complete bellows is made in a standard length called a block. Multiple blocks can be welded together to make a longer bellows.
Formed Bellows
F Series bellows is fabricated by longitudinally welding a thin metal strip to form a tube. Convolutions are then formed into the tube using hydraulic pressure.
Basic Design Considerations
The design of a bellows must take into account many interrelated characteristics and conditions. Some of the basic design parameters include:
- Stroke
- Spring Rate/Load
- Cycle Life
- Pressure Rating
- Temperature
- Size Restrictions
- Media (chemical compatibility)
- Type of Movement
- End of Connections and Mounting
<%=company%>, 33 Defco Park Rd., North Haven, CT 06473. Tel: 800-243-6039. Fax: 203-234-7233.