Taking the strain: anti-vibration specification for industry

17 August, 2016

With such a wide variety of anti-vibration products on the market – anti-vibration mounts, buffers and pads to name a few – specification can, at the outset, feel like a minefield. How can design engineers ensure their mount delivers the right performance characteristics and are not hampered by incorrect installation, misuse or environmental factors? By working through the following best practice guidelines, engineers can rest assured that their mounts will continue to perform over a long and arduous life cycle.

Operating conditions, such as the temperature and environment of the application, will help determine the most suitable solution. However, other factors must be assessed through calculation & analysis to narrow the field and enable informed specification of a suitable anti-vibration mounting solution, such as:

• Deflection.

• Centre of gravity.

• Equipment configuration.

• Disturbing frequency.

• Mass moment of inertia.

• Static loading.

• Shock/thrust loading.

• Alignment.

• Natural frequency.

Assessed alone, none of the above will provide a complete picture of the system performance and if any of the input data is inaccurate, then the selected mount may not give the optimal performance characteristics. For example, understanding the centre of gravity helps to determine the loading at each mounting position, and as the loading at each position may vary, it may be necessary to select different products across the mounting system. Calculations also help ensure that mounts are not overloaded – either statically or dynamically – which will hamper performance. Ideally, all calculations should be balanced with other aspects of a system’s design, such as gross motion and dynamic conditions, to achieve the best possible isolation of vibration once the mount is installed.

Composition

The composition of a mount is also a consideration. Solutions manufactured through rubber-to-metal bonding offer the greatest benefits, for a number of reasons. Foremost is the high load bearing capacity of rubber coupled with its low modulus of elasticity, which allows the natural frequency of the mount to be tuned. Natural rubber can also be chemically manipulated to provide a broad range of characteristics through the introduction of particular additives to achieve different hardness grades or damping capabilities according to the application. Finally, when bonded to metal, the inherent strength of rubber is dramatically increased to give an even higher load capacity. For damping applications, rubber outperforms steel coil or leaf springs as the use of the latter can result in excessive vibration transmission.