The Factors That Can Reduce The Service Life Of A Metal Bellows Coupling

Metal Bellows Couplings operate reliably throughout the entire service life of an installation if the coupling is properly designed. However, applications are becoming more and more diverse, requiring you to consider additional criteria when selecting and designing couplings. This article will highlight the factors that affect the service life of Metal bellows couplings.

1. Introduction to Metal Bellows Couplings?

Metal Bellows Couplings (Ringfeder GWB Coupling) is an encoder coupling, used in the field of mechanical engineering, where torque or rotational motion must be transmitted from one shaft to another with the highest angular accuracy. With a compact design, stainless steel material, Ringfeder GWB Coupling compensates for radial, axial and angular misalignments; operates in working environments with temperatures from - 30°C to 100°C.

Ringfeder Bellows Coupling is suitable for industrial machines such as: Pumps with axial and vertical drives, High dynamic portal drives, Spindle lifting units, Linear units, Special machines…

However, if not used properly, the service life of the encoder coupling will be significantly reduced, causing damage to equipment and increasing maintenance costs.

>>> Learn more: Encoder Couplings: Unlocking Precision & Reliability with Metal Bellows Couplings GWB

2. 4 factors that can reduce the service life of a metal bellows coupling:

2.1. Steel material directly affects the durability of Ringfeder GWB Coupling

Ringfeder encoder couplings are mostly made of austenitic stainless steel (face-centered cubic steel, or FCC), which is superior to martensitic steel (body-centered cubic steel, or BCC). Thanks to this structure, austenitic steel has a good combination of mechanical properties and high corrosion resistance. This term refers to the number of load cycles that a material can withstand within a certain stress range before it fails.

However, based on the Woehler diagram - a diagram that describes the relationship between the number of load cycles and the level of stress that the material can withstand - we can see that the austenitic steel used for Metal Bellows Coupling still has a wear limit. That is, after a certain load cycle, the material will begin to weaken and may crack.

In other words, if the encoder coupling is frequently operated with excessive torque loads and other stresses (such as axial and lateral movement between the clamping heads). These factors increase the risk of premature failure of the entire transmission.

>>> Although austenitic steel is very good, to prolong the life of the coupling, avoid continuous operation with excessive torque.

2.2. Use in servo systems

Metal bellows couplings are often used in precision servo motors, such as CNC machines and table controllers, where fast positioning characteristics are required. These applications generate cyclic loads, high acceleration and deceleration parameters, which cause cyclic stresses on the metal bellows of the couplings. The ends of the metal bellows or their connection to the clamping hub form particularly high-load locations and are therefore critical locations:

This connection is not only subjected to the transmitted torque but also to the concentrated alternating bending moments that may arise due to inaccuracies in alignment and/or unavoidable imbalances.

>>> Solution:

• Use specially designed couplings to withstand dynamic loads if the system runs at high frequencies

• Careful installation, ensuring concentricity between shafts

2.3. Increasing the diameter size is not always good

Although increasing the diameter of the metal bellows will reduce the torque-induced load. However, alternating bending stresses can occur due to the increased transverse stiffness: and these will have a similar negative impact on service life - especially with the same alignment accuracy, higher speeds and higher unbalance for the coupling due to the higher mass.

>>> When selecting a coupling, it is important to balance size and flexibility. Do not rely on size alone to increase durability.

2.4. Reducing torsional vibrations of Metal Bellows Coupling

For systems with sudden starting or stopping loads, torsional vibrations are a danger to the coupling. These vibrations subject the coupling to repeated loads in a short period of time - causing high wear.

The following additional measures will reduce torsional vibrations of the Ringfeder GWB, as they reduce unnecessary peak loads and additional load cycles:

- Ensure that the coupling remains torsional and is not excessively bulked.

- Connect the metal bellows to the clamping hub.

>>> These solutions will minimize the additional loads arising from unavoidable lateral movements and/or angular misalignments and will increase the service life of the coupling.

3. Ringfeder Encoder Coupling - GWB AKN series

Compared to the couplings offered by competitors, the RINGFEDER^® GWB metal bellows coupling stands out thanks to its optimized connection to the metal bellows, which has virtually no notching effects and at the same time possesses minimal damping properties, thus reducing torque peaks at this critical location.

In addition, a rigid and consistent torque transmission is ensured by gluing the two sides of the metal bellows to the clamp shaft. The central connection of the metal bellows to the shaft with particularly tight tolerances reduces the possibility of unbalanced excitation and is therefore ideal for applications involving high speed levels.

Ringfeder GWB series includes: GWB AK, GWB AKD, GWB AKN, GWB CKN, GWB DKN, GWB EKN, GWB PKA, GWB Z5106.

The metal bellows couplings from the 'AKN' series boast trusted quality and increased torsional stiffness. The reduced shafts in the element guarantee for high stiffness while at the same time compensating angular, axial and radial misalignments. The shaft connection is established by means of clamping hubs on both sides.

4. Choosing a reputable distributor of Ringfeder Metal Bellows Couplings supplier?

Dai Hong Phat Corp is an authorized distributor of Ringfeder Germany, specializing in providing transmission coupling lines, including Metal Bellows Couplings. With over 15 years of experience in the industry, Dai Hong Phat is committed to consistently delivering genuine, high-quality products to customers.

When purchasing at Dai Hong Phat, you will receive:

• Genuine products, full CO/CQ documents.

• Goods are always available in stock, with fast delivery, and reducing machine downtime

• A dedicated technical consulting team, providing suitable options for the factory.

• Free conversion of product parameters upon request.

• Provide product technical drawings (upon request)

• Professional processing workshop refines products upon request.

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