What is vibration isolation? Why vibration isolation is needed ?

The process of isolating an object such as isolating machinery from the source of vibration is called vibration isolation. When motorized equipment such as electric motors, fans, or pumps is mounted to a solid structure then the chances of transferring energy from the equipment to the structure in the form of vibration are high. These vibrations could create noise and damage the equipment too. The vibration isolation will be very useful for many industries.

What is Vibration Isolation?

Vibration isolation is a technique widely used to reduce or suppress unwanted vibrations in structures and machinery, protecting sensitive components and ensuring system longevity. This approach is critical across industries like aerospace and defense, where vibration-induced damage can have serious consequences.

By inserting a resilient component, or isolator, between a vibration source and the device or structure, vibration isolation minimizes the transmission of forces. Common isolators include metal springs, rubber mounts, and pneumatic mounts, each designed to absorb or dampen vibrations effectively.

Vibration isolation is typically applied in two main scenarios:

1. To protect the foundation or structure from excessive forces caused by harmonic excitation or unbalanced rotating masses in the vibrating system.
2. To safeguard delicate instruments or devices from unwanted motion originating from the base or foundation they’re mounted on.

What causes vibration?

Vibration can be seen in motorized equipment, and it is created by the back and forth movement or oscillation of the machines and components. The vibrations can be created in an industrial plant by a drive motor, pump, compressor, etc. The vibrations are usually created by the rotation motion of the equipment parts or by the electrical supply frequency. The vibration could happen because of the following.

• Rotational shaft speed
• Electric motor rotor bar frequencies
• Electrical supply frequencies
• Gear meshing frequencies
• Impeller blade pass frequencies
• Bearing frequencies
• Belt frequencies
• External frequencies

What is the function of the vibration isolator?

The vibration isolator would decrease the transmitted vibration magnitude to the equipment. The required feature for an isolator is resilient load supporting means and energy dissipating means.

What is vibration damping and how does a vibration damper work?

Damping is the process in which the vibrational energy will be converted into heat or sound energy. A vibration damper would take energy out of a system and reduce the vibration.

A damper would act as the brake for the equipment mounted on the isolator, damping would reduce the motion by using friction. Friction damping occurs when the friction between the sliding parts slows down the movement between parts, viscous damping occurs with resistance to fluid or airflow.

Damped and un-damped vibration

In damped vibration energy will be lost during oscillation, while in un-damped vibration there won’t be any energy loss during oscillation.

How does vibration isolation work?

If the equipment is properly isolated then it would only create less vibration which would be negligible. In order to achieve vibration isolation, isolators are used and this device would be placed between the equipment and the structure so that it can create a low natural frequency support system for the equipment.

Classification of vibration isolation

Passive vibration isolation

Mostly the passive isolation system is comprised of a mass, spring, and a damper. This type uses passive techniques to reduce vibrations, such as rubber pads or mechanical spring. The spring and mass would create a natural frequency and the damping would affect the natural frequency. So during the vibration, the transfer of energy takes place at the natural frequency. The natural frequency amplification is decreased by damping.

Active vibration isolation

In the case of active vibration isolation, it has a spring and a feedback circuit that consists of a sensor, a controller, and an actuator. This is mostly a servo mechanism and it uses a processor-based actuation methodology for vibration isolation. The vibrations will be transferred to the control circuit and then it is fed to the electromagnetic actuator and all of this process would reduce the vibration. This type is more accurate than passive isolators and there is no resonance in this system.

How to select a vibration isolator and what are the factors that must be considered while installing a vibration isolator?

• it must be selected according to the size and weight of the equipment that is to be isolated
• It must be selected according to the machine movement
• It must be selected according to the operating environment
• Temperature and magnetism
• Nature of the vibration
• Operating pressure
• Indoor or outdoor
• Machine location, it must be kept away from sensitive materials as possible
• The isolator units must be properly sized
• Location of isolators
• Stability of the isolator is an important factor, snubbers must be used to restrain the sideway motion and the spring diameter must be greater than its compressed height.
• Adjustment- the spring must not be fully compressed and the spring must-have free travel.
• Vibration short circuits must be eliminated – if there is any mechanical connection between the machine and the foundation that bypasses the isolators, such as conduits, pipes, etc, must be eliminated.
• Fail-safe operation – There must be mechanical support for the machine so that the spring won’t be damaged.

What are the effects of vibration?

The equipment would be damaged because of the vibration, the vibration could create noise, it can create safety problems, and it can also lead to the degradation of the plant’s working condition. The vibration can cause the equipment to use more power and may damage product quality. 

What is the importance of vibration isolation in industries?

• By doing vibration isolation we can protect sensitive machinery
• We can reduce the sound by vibration isolation
• We can provide safety for the equipment
• Quality protection

Vibration Isolation Materials and Types of Isolators

Various materials and types of isolators can be selected based on specific vibration isolation needs. Common materials include:

• Rubber: Known for its flexibility and affordability, rubber isolators are suitable for low-frequency applications and help reduce noise.
• Metal Springs: Used in high-weight applications and environments with high temperatures or exposure to chemicals.
• Viscous Dampers: Filled with a fluid, these dampers absorb energy effectively, providing a smooth reduction in vibration.
• Air Springs: Suitable for sensitive equipment, they use compressed air to support the load and reduce vibration, often in conjunction with active systems for high precision.

Vibration Isolation in Special Environments

• Marine Applications: In environments exposed to saltwater and moisture, isolators are built to withstand corrosion. Marine-grade isolators are often made with protective coatings and corrosion-resistant metals.
• Extreme Temperature Environments: Materials like silicone rubber or metals are used for isolators in environments with extreme cold or heat, such as in aerospace or oil exploration equipment.
• Cleanroom and Laboratory Applications: Vibration isolation is crucial in labs for equipment like optical microscopes and precision scales. Here, isolators are often designed to prevent minute vibrations that could impact sensitive measurements.

What is the fundamental of vibration isolation?

The fundamental principle of vibration isolation is to reduce or prevent the transmission of vibrations from a vibrating source to other parts of a structure or to sensitive equipment. This is achieved by placing isolators, such as pads, springs, or dampers, between the vibration source (like a motor) and the structure it’s mounted on. These isolators absorb or dampen the energy, effectively lowering the amplitude of vibrations and preventing unwanted transmission that could lead to noise, structural damage, or interference with sensitive operations.

What is the best way to isolate vibrations?

The best way to isolate vibrations depends on the specific application, but generally involves selecting the right type of isolator based on frequency, load, and environmental conditions. Common methods include:

• Passive Isolation: Using pads, rubber mounts, springs, or air mounts to create a physical buffer that absorbs and dampens vibrations. These are ideal for less complex applications.
• Active Isolation: Incorporating sensors, actuators, and control systems to detect and counteract vibrations in real-time, providing precise isolation for sensitive equipment.
• Combination Approach: Many applications benefit from combining passive and active isolation techniques, especially when both high and low-frequency vibrations need to be controlled effectively.

Which of the following is the purpose of vibration isolation pads?

The purpose of vibration isolation pads includes:

1. Reducing Vibration Transmission: They prevent vibrations from passing from the equipment to the floor or structure, minimizing noise and potential structural damage.
2. Protecting Sensitive Equipment: Vibration pads help safeguard delicate machinery and electronics from external vibrations that could disrupt performance or cause wear.
3. Improving Workplace Safety and Comfort: By reducing noise and vibration, they create a safer, more comfortable environment for operators and personnel.

Trends and Innovations in Vibration Isolation

Recent advancements include smart materials and adaptive vibration isolation systems. Some innovations include:

• Magnetorheological (MR) Fluids: These fluids change viscosity when subjected to a magnetic field, allowing variable damping as per vibration levels.
• Active Noise-Canceling Vibration Systems: Using algorithms to detect and counteract vibrations, these systems adapt to real-time vibration changes in highly sensitive equipment, like those in semiconductor manufacturing.
• Self-Tuning Isolators: Designed to automatically adjust to different vibration frequencies, self-tuning isolators offer flexible solutions, especially for changing loads or environments.

Vibration Isolation Standards and Compliance

There are various industry standards and guidelines for vibration isolation, depending on the application:

• ISO 10816: Addresses vibration severity in rotating machinery.
• MIL-STD-810: Military standard that includes tests for vibration resistance for equipment used in extreme conditions.
• ASTM E756: For laboratory measurement of vibration damping properties, ensuring that vibration isolation materials meet performance criteria

What is the need for vibration isolators in electronics?

• Protection against physical shock
• It is used in industrial control computers and electronic systems
• Military ordinance computers
• Electronic equipment in transit in shipping containers
• Electronics and instruments for mining/drilling support vehicles

What are the applications and uses of vibration isolation?  

• It is used in many industries to protect the equipment
• The vibration isolation is done in two ways, one way is to reduce the transmission of vibration from the equipment to where it is mounted and in other type, it would reduce the transmission of vibration velocity to the equipment.
• Heavy loads, pumps, & compressors
• Machinery and instruments
• Vehicles and aviation
• Aerospace
• Electron microscopes