Foundation provided below the superstructure of vibrating and rotating machine for installation, is known as machine foundation. It essentially consists of a mass of concrete. Design of machine foundation involves consideration of static load and kinetic forces.
The load of the machine is the static load which is of minor importance in the design of a machine foundation. The moving parts of the machine develop inertia forces which are the major forces to be considered in its design. The kinetic or inertia forces are periodic and vibratory in nature, the magnitude of which depends on the type of machine. The general principles of machine design are enumerated as follows:
1. Machine foundations should be isolated from the adjoining parts of the building by leaving a gap around it to avoid the transmission of vibrations. The gap is filled with suitable insulator or dampers.
2. The foundation should be stiff and rigid to avoid possibilities of tilt in it.
3. In static state, the resultant of forces acting on machine foundation should pass through the c.g of the contact area of the base.
4. The weight of the foundation block should be adequate. It should be able to absorb vibrations and resist resonance between adjoining soil and the machine. The weight of the foundation block may be assumed roughly 2.5 times the weight of the machine.
5. A vibration absorbing medium is introduced between bottom of the foundation block and the floor on which it is resting. This medium may be in form of a rubber or leather gasket, layer of sawdust etc. Sometimes, springs are used below the machine itself to prevent the development of the vibrations. It is advised that relevant data of machine should be obtained from the manufacturer before any design of foundation is undertaken.
Types Of Machine Foundation:
1. Block Type Machine Foundation:
2. Box Or Caisson Type Machine Foundation:
3. Wall Type:
4. Framed Type:
5. Non-Rigid or Flexible Type: