It become necessary to test engineering materials before they are accepted for processing, buying or applying to determine whatever or not they meet the spefications required. One of the tests is hardness test. The Rockwell and brinell machines are those most commonly used for this purpose. PROCUDURE AND LABORATORY REPORT 1. Understad thoroughly the operation of each machine, and check its operation before proceeding. 2.
Check the calibration of the Rockwell machines with standard calibration test blocks for the scale selected. 3. Using the appropriate scale a. Check the hardness of each test specimen on Rockwell test machine. b. Tabulate the results. c. Convert all readings to either Rb or Rc values. d. Apply the cylindrical correction factors for cylindrical specimens. 4. Using the hardness conversation chart, find the tensile strength of the steel samples. OPERATIONS OF HARDNESS TESTING EQUIPMENT The following operation guide is a general one. Follow it carefully and observe caution and care at every step of the operation.
No motion of any controls should be abrupt or using too much force, both of which would damage the instrument. Step 1: Calibration Operate the tester using both test blocks and record what you get and what they are supposed to be. Thus you can scale your data accordingly be as close as the correct numbers corresponding to the actual hardness. Step 2: testing to sample STEP BY STEP OPERATION 1. Selected the correct combination of weights and penetrators for the hardness scale you wish to use . 2. Make certain that the crank is in forward position. . Place sample on the anvil. 4. Slowly turn the wheel spokes clockwise. This raises the anvil and sample away toward the penetrator tip. After contact is gently made, continue raising sample until small pointer is about in line with small black dot and larger pointer is within colored sector. The minor load has now been applied to the sample. 5. After 4th step larger pointer on the dial is nearly vertical . Now turn the knurled collard until ‘set’ line on the dial scale is in line with larger pointer. 6. Depress trip lever . his triggers the mechanism that applies the major load. Crank will automatically move away from you. 7. After crank has come to rest gently pull the crank toward you as far as it will go. If this is done abruptly a false reading will be obtained because of jarring. 8. Then record the scale reading of large pointer . the black scale is read for the diamond penetrator and the red scale is for ball penetrators. 9. Remove the minor load which remains on the specimen by lowering the anvil the wheel counterclockwise . move the sample to posisition for next test and repeat the steps above.