vibration isolator for machines

Rubber-metal suspensions, vibration isolatoring

vibration isolatoring is an elastic support which aims to reduce the level of environmental vibration transferral to the machine as well as reducing the levels which it itself generates.  This is achieved by introducing an isolator between the vibrating table and the source of the disturbance, therefore reducing vibration. 

• Elastomeric, a natural synthetic rubber. This type can be moulded to specified shapes and rigidities. With regard to its nature and quality, it is able to withstand large deformations and then return to its original state without occurring any damage.  It has an exceptional extendibility and great deformability; as a result, it can be used in extreme elongations. 

Natural rubber elastomers provide more favourable mechanic properties for isolation since they offer low energy dissipation which allow their transmit ability to be lower than other synthetic rubbers. Their excellent mechanical properties allow them to achieve stable solutions over time. In terms of limitations, the natural rubber deteriorates under the influence of oils and elevated ambient temperatures. Optimisation of the elastomer mix increases its resistance to UV rays and the Ozone. 

Silicone rubber is one of the most expensive elastomers on the market, but it presents notable stable properties and provides an effective isolation within a wide temperature range. 

Most of the elastomeric isolators should not be subjected to major deformations for long periods of time. An isolator with a great static deflection can temporarily perform satisfactorily, but an overload propitiates permanent deformations equal to the breaking of polymeric bonds. 

• Plastic isolators are less costly and offer exceptional uniformity.  Materials most frequently used are polyethylene and styrene. The main disadvantage of these isolators is that they have poor mechanical properties, which is to say that they offer an inferior capacity to resist loads or forces and likewise excessive creep, and permanent deformation.  Microcellular polyurethanes exist which can greatly alleviate these problems. For such elastomers, it is essential that their load deflection curve be “S” shaped, which is to say, a linear section, followed by a degressive one then finally a progressive section.

• Metal springs.  These are normally used in applications which require significant static deflexions. These isolators are used when it is necessary to achieve very low natural frequencies and require stability in deflexion over time.  A disadvantage of metal springs is that in order to obtain low energy dissipation, it is necessary to attach spring systems which greatly raise the cost of the solution.