The literal meaning of couplings in industrial engineering is: a mechanical connection or joint that is established between two devices. A coupling is usually used to transmit power from one shaft to another, particularly when the shafts are not aligned to each other. However, more often than not, couplings are often ignored as trivial devices, which can be very harmful to industrial machinery.

A prime example of a coupling is the universal joint that is used to connect an automobile’s drive shaft to the engine. There are basically two types of couplings which are rigid and flexible couplings. Rigid couplings don’t enable any flexing of the two connecting shafts. Rigid couplings are generally used in applications where the shaft itself will absorb any minor flexing from true alignment. Quick disconnect couplings and flexible shaft couplings are two other types of common couplings used.

Even though flexible couplings are more complex they are more commonly used than rigid couplings. These couplings usually use inert and non-conductive elastomeric materials which provide flexibility. These materials are also used to electrically insulate one component from the other. There are three types of flexible couplings which are mechanical element, elastomeric element, and metallic element. Mechanical element couplings rely on the loose fit or rolling and/or sliding connections within the coupling that absorb any stresses and forces. The resilient material of elastomeric couplings such as rubber, nylon or another type of plastic, absorb the stresses. A mechanical element coupling consists of a thin metal diaphragm which flexes when it is stressed. . Each group of couplings has its individual uses. For example, metallic couplings are best suited for use in high temperature and low inertia operations, whereas elastometric types are suited for lightweight applications.

Couplings are made with finite or infinite life spans. Because couplings deal with a lot of stress, they may easily deteriorate or expand. In many cases, couplings will only operate as long as the projected lifetime of the machine they are connected to. However, infinite lifetime couplings are built to last forever and may be sealed so their mechanical components aren’t affected by dirt, debris and liquids. Both types of couplings may need regular maintenance and worn components may need to be replaced.

Choosing the right coupling can enhance the life of the machinery. Some factors that are taken into account while choosing the right types of coupling are type of machinery, vibration quotient, temperature conditions or any space-related limitations. A good coupling must also be able to bear high load and should be able to transmit higher torque. Moreover, couplings should also be corrosion resistant.

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