Short Answer:

Balancing is necessary to make rotating or reciprocating machines run smoothly without vibration or noise. It helps in reducing wear and tear on bearings and shafts, improves machine performance, and increases life of mechanical parts. Proper balancing ensures that the centrifugal forces created by moving parts cancel each other completely.

If a machine is not properly balanced, it causes excessive vibration, noise, and energy loss. This leads to mechanical failure and poor working efficiency. Therefore, balancing is very important to keep machines stable, efficient, and safe during operation.

Detailed Explanation :

Why is Balancing Necessary

Balancing is necessary in all rotating and reciprocating machines to ensure smooth operation and to prevent unwanted vibrations. When a part rotates, centrifugal forces act on it due to its mass and speed. If the mass is not evenly distributed around the axis of rotation, unbalanced forces and couples are produced. These unbalanced forces create vibration, noise, and additional stress on machine parts. The purpose of balancing is to distribute the mass evenly so that the resultant centrifugal force and couple become zero, allowing the machine to run steadily and safely.

In rotating machinery like turbines, motors, fans, or flywheels, unbalanced masses lead to excessive vibrations that may cause failure of bearings, bending of shafts, and loosening of joints. Balancing eliminates these issues and ensures smooth rotation. It is also important in reciprocating machines, such as engines and compressors, where parts move back and forth. In such systems, balancing reduces the shaking forces and moments generated during motion.

Balancing is necessary for several main reasons, which are explained below:

1. To Reduce Vibration and Noise:
   When a rotating mass is unbalanced, the centrifugal force produced during rotation acts unevenly on the shaft. This causes vibration in the whole system, leading to noise and discomfort. These vibrations can affect nearby components, causing mechanical and structural problems. Proper balancing ensures that these forces cancel each other out, resulting in quiet and stable operation.
2. To Prevent Wear and Tear:
   Unbalanced machines put extra load on bearings, shafts, and supports. This uneven load causes wear on mechanical parts, leading to frequent maintenance and early failure. Balancing reduces these loads and keeps the motion uniform, thus increasing the life of bearings and other machine components.
3. To Improve Efficiency and Performance:
   A balanced machine runs smoothly and consumes less energy because there are no unnecessary vibrations or frictional losses. It also delivers better output, as the energy from the motor or engine is used effectively for useful work rather than being wasted in overcoming unbalanced forces.
4. To Ensure Safety and Reliability:
   In large and high-speed machines such as turbines, engines, and generators, unbalanced forces can be very dangerous. They may cause the shaft to break or bearings to fail suddenly, leading to accidents or complete machine breakdown. Balancing makes these machines safe and reliable for continuous operation.
5. To Maintain Product Quality:
   In manufacturing processes like grinding, milling, and drilling, unbalanced rotating tools or spindles can lead to poor surface finish and uneven cutting. Balancing ensures the tool runs smoothly, producing accurate and high-quality products.
6. To Reduce Maintenance Costs:
   Machines that are well-balanced require less maintenance because they experience less vibration, wear, and fatigue. This helps save time and money in repairing or replacing parts and ensures longer machine life.

Balancing can be done in two main ways—static balancing and dynamic balancing. Static balancing ensures that the center of gravity of the rotating body lies on the axis of rotation, so the object remains steady at rest. Dynamic balancing is more complex and deals with the forces and couples when the body is in motion, ensuring both are zero during rotation. Both types of balancing are important to achieve full stability.

In practical applications, balancing is performed using balancing machines. These machines detect the amount and position of unbalance in a rotating part. Based on this information, small correction weights are added or removed to make the part perfectly balanced. For example, in vehicles, wheel balancing is done to prevent vibrations at high speed. Similarly, turbines and rotors are dynamically balanced to prevent operational problems.

In industries, balancing is a routine procedure performed during machine installation, maintenance, and manufacturing. Modern electronic balancing systems are capable of detecting even minor unbalances and suggesting corrective actions. This ensures high precision and safety in machine operation.

To summarize, balancing is not just about comfort or smooth operation; it is essential for the safety, efficiency, and longevity of mechanical systems. Without proper balancing, machines would wear out faster, consume more energy, and risk mechanical failure.

Conclusion:

Balancing is necessary to maintain smooth, vibration-free, and safe operation of machines. It prevents wear and tear, increases the life of mechanical parts, improves working efficiency, and ensures safety during operation. A properly balanced machine performs better, uses less energy, and provides reliable service for a longer time.