parts subjected to machine vibration

What is machine vibration?

Machine vibration is an unavoidable result found in the rotating, moving, and sliding machine assemblies due to improper tolerancing and clearance between rotating parts, misalignment, imbalance, wear, and no use of proper packing materials. Sudden vibration in the machinery are the symptoms, or the intimation of wrong is happening with the machine which may cause an accident.
But it is hard to find the source of the vibration. Because various parts are contributing to the machine to be in operation. It is possible for engineers and technicians by analysing frequency and amplitude to find the root cause of the vibration.

Vibration Frequency

Vibration frequency is the vibration or oscillation of the object per unit of time. It is a graphical representation of no vibration cycles per unit time (Second or minute). Analysis of the vibration frequency data gives the idea on the machine’s vibrations are within the range or exceed beyond the range. By comparing this data, a technician can take the desire action. It will help to maintain the machine in good condition.

Vibration Amplitude

Vibration amplitude is used to judge the serious effects (severity) of the vibration. Large amplitude due to large oscillation of the object indicates the machine subject to high vibrations, which can induce more stresses in the machine.

Displacement Amplitude

Displacement amplitude is the maximum distance travel by the oscillating body from its point of the reference line. High displacement of the amplitude indicates the high vibration in the machine components, which can cause severe damage to the machine or machine component.

Velocity Amplitude

Velocity amplitude is the speed of the oscillating body per unit of time. It can represent in the form of peak value or the RMS value(Root Means Square).

Acceleration Amplitude

Acceleration amplitude relates to the force acting on the machine component due to vibration. This phenomenon is useful to find the severity of fracture in large machines, which rotates at high speed. Acceleration due to force of vibration also causes failure in the lubrication system, which increases wear, tear, and heat up of machine components.

When machine vibration is a problem?

In the universe, all machines are subject to vibrations, but these are within the limit. Every machine is designed to absorb or resist vibration. But in some cases, machine vibrations may exceed their limits due to not taking care of machines, not doing their maintenance on time, and not maintaining the machines. Due to this, vibration becomes the problem.
It can damage various components of the machines, worker, increases time to make a product, reduces productivity, and causes an accident.

What are the causes of machine vibration?

Machine vibration causes various adverse effects on each component of the machine. Causes of the machine vibration are

Imbalance

Imbalance in the machine may cause the shifting of the center of gravity of the rotating object from the main centreline. It creates the imbalanced centrifugal force that causes the vibrations. A manufacturing defect in the casting, machining, and poor maintenance of the machines increases this problem. This problem becomes dangerous as the speed of the machine goes on increasing. It reduces the life of the Bearing and other machine components.

  • Static unbalance- Static unbalance cause when the central axis of the object becomes parallel to the rotating axis (centreline).
  • Couple unbalances- A couple of unbalance happens when two unbalances exist 180 degrees apart but in different planes.
  • Dynamic unbalance- Dynamic unbalance causes when the rotating centreline does not coincide with the principal center axis.

Misalignment

Misalignment in the axis of the fixing component causes machine vibration. During the assembly, an axis of both the machine are in parallel but not in align position, then it is known as parallel misalignment. It may cause during the assembly or develop with time due to the poor fixing arrangement, thermal expansion, and improper maintenance.

Wear

Due to frequent rotational movement of the bearings, gears, or belt drives start becoming wear out. Pitting of the internal recess of the bearing can cause a vibration when any bearing roller passes through this area. Damage to the internal and external recess, cage, or another rolling element can cause vibrations.

Chipped or Wear out surfaces of the gear due to high load and rotational moment causes vibration. Keys of the gears pullies or shaft becomes loose and cause vibrations.

Poor lubrication in bearing, gears, or other rotating parts causes wears, which further creates vibrations.

Looseness

During the maintenance, if any machine part is not fixed correctly, then it creates vibration. So there might chance of damage to the other machine component. In some cases, loose-fitting of the gear or bearing causes more wear or their surfaces which may cause the vibrations.

Bad foundation

Some of the machines mount on the ground, and some of them clamped to the ground. So, it is necessary to have a good foundation to make it possible. If the foundation is not good, then it creates vibrations in the machine.

Improper use of fixing and packing material

The base of the machines is designed to absorb the vibrations and pass them to the earth’s surface. But, fixing the machine base is not correct with the proper packing material, then it causes vibrations. Packing materials help to absorb the vibrations to some extent.

Effects of Machine Vibration

Machine vibration can cause the below problems.

  1. Wear and tear of the various machine components
  2. Creates noise
  3. Damage the machine
  4. Creates safety issues
  5. Consume more power
  6. Lower the product quality
  7. May cause accidents and stop production plants.
  8. Unplanned downtime

Conclusion on Machine Vibration

Machine vibration creates various problems for the man, machine, and organization. So, it is necessary to treat it.