Factors that influence the service life of rubber couplings
Rubber couplings have become indispensable elements in power transmission in industry. The components ensure smooth, low-vibration and shock-absorbing transmission of torques to machines. Modern rubber couplings are robust and low-maintenance. However, their service life depends on various factors. This article explains what these are and how the service life of rubber couplings can be influenced or extended.
Structure of rubber couplings
Rubber couplings are designed to minimize shocks, vibrations and load peaks. Couplings are made up of several components to create this balancing connection between two shafts.
The main components are metallic hubs made of steel, cast iron or aluminum, which are connected with a flexible element. The hubs are the connecting pieces with which the Coupling is connected to the shafts of the machine. They therefore transmit the torque to the elastic element located between them.
The elastic element in turn, the actual Coupling, is usually made of natural rubber, neoprene or silicone. These are heavy-duty elastomers that absorb load changes, shocks and vibrations. These rubber-like components are also able to absorb minor axial, radial and angular shaft misalignments.
The third component of a Coupling are the connecting elements which connect the metal hubs to the rubber element. These are usually clamping rings or screws.
Optional are Protective devices for the rubber coupling, such as covers, which protect the entire system from the effects of weather, dirt or chemical substances. This is also one point of the topic of which factors influence the service life of Couplings, which we will come to in a moment.
Factors that influence the service life of rubber couplings
1. excessive or uneven loads
Coupling systems also have their load limits. Uneven loads or temporarily excessive loads on rubber couplings can shorten their service life. Excessive loads lead to premature wear, and even damage to the Coupling is possible. If a Coupling is permanently driven beyond its load limits (max. Nm) or operated in a torque range for which it was not designed or calculated, failure is inevitable. It is therefore important to select exactly the right Coupling for your purposes. Saving money by installing a small Coupling often only leads to even higher costs.
2. shock loads and material fatigue
In addition to permanent overloading, a short-term but enormous load on the rubber coupling can also lead to a shortened service life. Sudden shutdowns or abrupt stops of the machine due to a malfunction weaken the material structure of the Coupling and lead to premature ageing. Only highly flexible couplings that are able to adequately dampen even very strong shocks and fluctuations can withstand such shocks.
3. ambient conditions: Temperature, humidity and chemicals
In addition to exceptional loads, environmental and weather influences are among the most common life-shortening factors for rubber couplings. Above all, extreme temperatures, high humidity and aggressive chemicals impair the elasticity of the coupling materials. If rubber couplings have to work under such conditions, which cannot be ruled out, regular inspection and replacement are essential.
It is also worth asking for rubber couplings that are specially designed for such environmental conditions and can withstand this rough treatment better than normal flexible rubber couplings. An example in this case would be a flexible silicone Coupling for operation in higher ambient temperatures.
4. imbalances and vibrations
Poor shaft alignment or imbalances in the system generate additional vibrations that stress the Coupling. Precise laser shaft alignment, as offered by PMP Service GmbH, can reduce the load and extend the service life.
5. neglected maintenance
Another factor that shortens the service life of rubber couplings is influenced by the operator of the system itself. Too little or no maintenance of the Coupling and drive systems means that wear and damage are not detected in good time. Maintenance at regular intervals is therefore mandatory for rubber couplings.
6. incorrect or insufficient lubrication
Closely related to inadequate maintenance as a factor in the reduced service life of rubber couplings is the care and lubrication of these. Many modern rubber couplings do not require lubrication during their service life. But there are special designs where it is necessary. No, insufficient or incorrect lubrication and care can lead to premature wear and malfunction. Couplings with installed ball bearings, for example, should be regreased regularly if possible.
7. incorrect alignment of shafts
The last factor to be mentioned here is often neglected in practice, but contributes significantly to shortening the service life of rubber couplings. If the shafts are misaligned, the loads and forces in the system are distributed unevenly. This leads to faster material fatigue and stresses in the rubber elements. More vibrations lead to faster wear and loss of efficiency.
How can the service life of rubber couplings be extended?
Some of the factors that shorten the service life of rubber couplings can be influenced, while others cannot. Basically, the following must be observed when selecting a Coupling and during operation:
On the one hand, make sure that the selected Coupling has been selected on the basis of a torsional vibration calculation or a torsional vibration analysis and that this document is accessible.
On the other hand, it is important to visually inspect the Coupling regularly and to observe the maintenance intervals specified by the manufacturer and the recommended service life. Professional selection and high quality should be ensured. Well-known manufacturers such as CENTA, STROMAG, VULKAN or REICH guarantee high quality and robust Couplings.
Regular inspections and optimum operating conditions contribute to the longevity of the coupling systems. PMP Service GmbH is always at your side. You can read detailed tips on increasing service life in our article Strategies for increasing the service life of rubber couplings.
