Standard wire rope isolators consist of stainless steel stranded cable threaded through aluminum alloy retaining bars that are mounted for effective shock and vibration isolation. Wire rope isolators are also constructed with corrosion resistant metal, which are environmentally stable with high performance shock that are unaffected by varying temperatures, chemicals, oils, ozone and abrasives. Wire rope isolators feature a crimping pattern, a variety of mounting options and sizes. They are able to effectively meet performance requirements in commercial, industrial and defense industries.
The construction of wire rope isolators (also known as the cable mount) are no doubt an ingenious design. Stainless steel wires are twisted into a cable, and are mounted between two bars. As you change the thickness of the cable, the number of loops and the angle of mounting will result in specific behavior under a given shock or vibration load. Such construction allows wire rope isolators to be fine-tuned based on the specific users’ requirement.
The upsides of wire rope isolators are the ability to combine a high level of both vibration isolation and shock, in combination with small dimensions relatively. Also, since wire rope isolators are limited by their own construction, they can be loaded in any direction without the likeliness of malfunctioning.
Wire rope isolators do not have to be maintained and are not prone to aging due to the external factors such as oil, chemical, salt water and varying temperatures. The applications of wire rope isolators are mostly found in circumstances where equipment needs to be mounted against shock or vibration, but where sound isolation isn’t the priority.
Keeping equipment perfectly balanced can be an expensive task, and adding structural reinforcements are often not adequate. However, with the help of a wire rope isolator (when done upfront), it can be a cost-effective way to address vibration and save equipment structures from fatigue.
Machines and electronics can be damaged by vibrations, thus why wire rope isolators were created to be incorporated into the design along with air springs or elastomers to prevent it. But keep in mind that elastomers only attenuate vibration and noise level. Wire rope isolators on the other hand are able to attenuate shock as well.
Wire rope isolators come in with a wide array of mounting options and sizes with specifications to accommodate commercial, industrial and defense requirement including ML standards. One of the common models, the compact wire rope isolators, can be installed just a single point of attachment at each interface on a machine.
There are a few different types of wire rope isolators. They are:
Many mounting type wire rope isolators include a combination of a few different mounting options such as through-hole, countersunk and threaded bars. All configurations and models are available in the market for people to choose from. Some models of mounting type wire rope isolators have reduced mounting options available due to limited fastener installation space. If necessary, consult your manufacturers or supplies regarding the mounting options available, or if the preferred mounting configuration may be missing.
This type of rope isolators can normally be purchased either with full number of loops or a few as two loops (reduced-loop). The number of loops is always indicated in the product specification. Full loop type wire rope isolators can yield good performance, and the performance indicator for reduced loop wire rope isolators can be obtained by a simple ratio.
Wire rope isolators are often available with a bellmouth option as well. The bellmouth type wire rope isolators features mount bars with radii manufactured into the wire rope hold edges. This type of wire rope isolator is often recommended for high fatigue applications where machines and equipment have to constantly undergo rigorous vibrations.
Note that the wire rope isolators regardless of the type exhibit non-linear stiffness so that small deflections (normally connected to vibration isolation) involve distinct spring rates. To predict system performance, the vibration stiffness value and shock stiffness values are taken into account for the related calculation. Just keep in mind that the stiffness values are for the full-loop type wire rope isolators, and the reduced-loop type wire rope isolators have stiffness that is calculated as the unit’s standard stiffness times the ratio of actual looks to the standard number of full loops.
The wire rope isolator selection is essential a three-step process. First and foremost, the designers define the system into which the wire rope isolator is going. This is done by determining the supported load, number of isolators needed to support the load, and whether the application will see just rolling or compression. Next, the engineers define the excitation and natural system frequencies, then calculate the maximum stiffness for the wire rope isolator. Lastly, before contacting the manufacturer, make sure that the wire rope isolator is protected against shock loads. The relevant values in the calculation are depended on allowable transmitted acceleration, maximum isolator stiffness, response deflection, and allowable deflection.
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