Hardness Testing is an NDT method used to measure hardness of materials.Material’s hardness defined as the
resistance of the material to deformation, penetration, scratching, or other physical force. The most common hardness test methods used in today`s technology:
• Rockwell hardness test
• Brinell hardness
• Vickers hardness
• Knoop hardness
• Shore hardness
• Mohs Hardness
• Barcol Hardness
Hardness tester operating principle is based on UCI (ultrasonic contact impedance) method. Basic components of the hardness tester are: sensor and electronic sensor data conversion and measurement data processing unit. The metal shaft forming a part of the hardness tester has a diamond pyramid fixed on its and. The shaft is oscillating with its own resonance frequency. Load created by the user’s hand enables the diamond pyramid to penetrate the material and to change the shaft’s resonance frequency. Variation of shaft’s own resonance frequency is proportional to shaft-into-material penetration depth. Since shaft-into-material penetration depth is the hardness factor one can see dependence between F (variation of shaft’s resonance frequency) and H (material hardness): H = f (F) . The hardness tester electronic unit receives frequency signal from the sensor, converts it into hardness units, withdraws measurement results to the display and performs statistical processing and other functions of particular hardness tester