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Monday, January 14, 2019

                  Brinell  Hardness Test 


- This test is nothing but to check how much the testing specimen is hard 
- The machine use for this process is brinell hardness tesing machine 
- This machine work on the principle of measurement of area of indentation for measuring the hardness value 
- Now for that indentation a ball indenter is used which produces circular indentation and on measuring diameter of that indenter and load applied on specimen 

Now hardness number is calculate by-
            BHN=(Load applied in Kg)/(indentation area in mm^2) 


Test Procedure :

- Clean surface from any type of grease or dust 
- Here we measure the area of indentation with help of micrometer microscope so surface should be polish by 0 or 00 paper 
- In machine specimen is placed on anvil and hand wheel is rotated so that specimen along with anvil move up and it make contact with ball indenter 
- The required load is applied by using gear driven screw by lowering handle and ball indents into specimen 
- So as the handle rotate specimen is going up and make contact with indenter for measuring the diameter of indenter 
- Small indenter diameter indicate high hardness number of metal 


Advantages of Brinell Hardness Test :

- More useful for measuring hardness of heterogeneous materials
- Cost of testing is low 
- Skilled operator is not required 
- Use for testing of soft metals 


Limitation/drawbacks of Brinell Hardness Test :

- Due to large size of ball and high load impression are larger,which decreases useful life of component 
- If hard material is test ball indenter will deform 
- Cannot use for material having hardness number more than 350 BHN
- Not use on final component due to large indentation 
- Dependent of load 


Application :

-This test is use for gray cast iron, copper and its alloy aluminium Etc.

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