How To Choose the Right Isolator For Your Military Rack

Choosing the right isolator for your rack is crucial for minimizing vibrations and enhancing equipment stability. It protects sensitive military equipment from vibration, shock, and environmental stress. The isolator selection directly impacts the durability, stability and performance of the equipment it protects. Isolators, sometimes called stabilizers, can be added to the base or sides of a rack, cabinet, or enclosure to buffer vibrations. 

Here, we’ll look at how to assess the risks of vibration and shock and the different types of isolators used to mitigate them.

Equipment Sensitivity

Electronic equipment can be weakened or damaged by physical shock and vibration in a number of ways. Sometimes a single large incident, such as a drop or bump, causes components to crack or dislodge. In other cases, exposure to vibration over a period of time causes problems. 

Left unchecked, vibration and shock can cause equipment to malfunction, lose data, or fail entirely. It can be difficult to detect when internal electronic components have been damaged, which means it is even more important to prevent damage by reducing exposure to vibration by installing appropriate isolators on the base of the rack, cabinet, or enclosure.

There are several key considerations to ensure optimal performance and protection:

1. Purpose: determine WHY you need an isolator 
2. Environment: consider the operating environment (temperature, humidity, dust)
3. Weight: calculate the total weight of the equipment to be supported, including center of gravity
4. Performance specifications: consider isolation frequency, damping ratio and load capacity
5. Mounting options: check compatibility within the physical dimensions of your setup

The load capacity of an isolator is crucial to ensure it can effectively support the weight of your rack and equipment without bottoming out or overloading. Consider:

• Total weight of the equipment plus any accessories
• Load distribution to avoid excessive strain on any single isolator
• Dynamic load adjustments if equipment shifts during use

Consider Sources of Vibration and Shock

When determining the type, size, and configuration of an isolator for an application, it’s important to anticipate typical sources of vibration and plan for the unexpected as well. Keep in mind that vibrations can cause damage before equipment is even installed and in use.

Vibration and physical shock come from many sources. These can include things in the equipment’s local environment, unanticipated incidents, or even vibrations generated by the equipment itself. Depending on how delicate electronic components are, and how robust the racking, enclosures, or cabinets that hold them are, vibrations will have a different effect. 

Some sources of vibration and shock include:

• Pulsing from nearby machinery or motors in manufacturing or industrial facilities
• Rattling and airflow from fans or HVAC equipment
• Traffic from heavy vehicles driving past a building 
• Transportation of enclosures or cabinets over rough roads or unpaved ground
• Air turbulence that jostles or bounces avionics instrumentation during flight
• Rocking motion and crashing waves on a ship
• In outdoor applications, thunder, heavy rain, strong winds, or seismic events

Generally, there are two types of vibrations to consider when selecting an isolator. One is sinusoidal vibration, which occurs predictably at a regular, cyclic frequency. The other is random vibration. As its name suggests, this type of vibration occurs at many different frequencies and amplitudes, with no predictable cycle or period. It’s important to plan for both types of vibration.

Military equipment is exposed to both vibration and shock, especially in mobile settings like vehicles, aircraft or ships. Key requirements include:

• Frequency range of vibrations that the isolator needs to handle
• Amplitude and direction of shocks to absorb (random, axial, angular)
• Required damping properties to prevent resonance and prolong equipment life. 

Isolator Material and Properties

Most isolators consist of two primary components: a spring and a damper. The spring is often made from wire rope, or a similar material, that is coiled and absorbs movement due to vibration and shock, helping the enclosure maintain its correct position. The damper is a plate that is connected to the spring and mounted to the base of a rack or enclosure and reduces the amplitude (i.e., energy level) of the waves. 

Depending on the application, the frequency and amplitude of the vibration, anticipated loading, and operating conditions, one of these isolator designs may be appropriate:

• Wire rope isolators. Known for their high tolerance to temperature extremes and resistance to environmental conditions. They provide reliable protection against both shock and vibration.
• Spring Isolators. Wire rope is strong and flexible to withstand heavy loads and a long service life, especially for high-frequency vibrations. They must be carefully selected to avoid resonance at specific frequencies.
• Elastomer Isolators. Often used for small or lighter-duty applications, materials like nitrile rubber and neoprene offer good low-frequency vibration isolation and are cost-effective. However, they may be less durable under extreme temperatures and UV exposure.
• Active Isolators. Active isolators are electronically controlled isolators that use a combination of sensors and actuators to mitigate vibrations. 
• Air and fluid dampers. Suitable for heavier loads with customizable damping properties, but require regular maintenance. 

In heavy-duty applications, including military, maritime, aerospace, or communications industry settings, a spring isolator is often the most appropriate choice. They can be manufactured from different gauges of wire rope to different coil diameters and loading capacities. Dampers can be made from a variety of materials and thicknesses to provide adequate amplitude reduction. Isolator rack attachment is precise because many configurations are available for mounting and securing to cabinets, racking systems, or enclosures. 

Military applications must comply with strict standards to ensure equipment reliability. Common military standards such as MIL-STD-810, MIL-S-901 and MIL-STD-167 covers the environmental tests, shock tests and mechanical vibrations requirements. Isolators tested and certified to meet these standards will offer the assurance of quality and reliability needed. 

Learn More About Isolators From A&J Manufacturing

Selecting the right isolator for your military rack involves a careful assessment of environmental, operational, and load-specific requirements, as well as compliance with military standards. By considering factors like load capacity, vibration and shock demands, and environmental resistance, you can choose an isolator that will protect your equipment effectively. 

At A&J Manufacturing, we work with  a range of industrial partners (including ShockTech & IDC) that provide isolators in different sizes and configurations for light- to heavy-duty applications for the maritime, military, communications, and other industries. 

Our design engineers can also provide expertise when it comes to consultations and recommendations to help tailor to your needs; as well as helping coordinate computer analysis or physical unit testing to ensure performance and compliance. We also manufacture racks, cabinets, enclosures, and accessories including drawers, shelves, slide hardware, cooling fans and blowers, power strips, and exterior panels and hardware. Both commercial-off-the-shelf (COTS) and custom products are available.

Contact us to learn more about our isolator solutions or request a quote to get started.