Condition for selection of factor of safety

Condition for selection of factor of safety

 1.Effect of failure:

     The factors of the safety is high in applications where failure of machine part may result in serious accident. 

2. Type of load:

     Fs is low :- static external forces
     Fs is high:-impact load

3. Degree of accuracy in force analysis

     If forces acting on the machine component are precisely determined.

4. Material of component

     Homogeneous material :- Low Fs
     Non-homogeneous material :- High Fs

5. Reliability of components

     Fs increases with increasing reliability
e.g. power station equipments, defence equipments.

6. Cost of component

    High cost component :- High Fs
    Low cost component :-  Low Fs

7. Testing of machine element

    When the machine component can be tested under Excel conditions of service :- low Fs
    When it is not possible to test a machine part :- High Fs

8. Service conditions

    Corrosive atmosphere, high temperature environment :- High Fs

9. Quality of manufacture

    When quality of manufacture is high :- Low Fs
    When quality of manufacture is poor :- High Fs

 Note :-

               Here Fs is stands for high factor of safety

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