Rockwell Hardness block calibration service (HRA, HRB, HRC)

With the aim of serving customers with the best after-sales services, EMIN Vietnam has established the Equipment Inspection - Calibration - Repair Service Center. With the support from numerous equipment manufacturers in the world, EMIN Vietnam possesses well-prepared calibrating instruments. EMIN Vietnam has successfully repaired and calibrated specialized equipment in Vietnam, ensuring the quickness, effectiveness and convenience for customers. Only few technical trading company in Vietnam do possess this technical capacity including EMIN Vietnam.

>> Rockwell Hardness Test Plate (HRA, HRB, HRC)
Since 1914, the Rockwell hardness concept has been widely used in the mechanical science industry. Using multiple measuring tips of different shapes and materials, load <150kg. Evaluation results depend on the depth of the dent.

>> Other information
The Rockwell hardness test was proposed by a Viennese professor named Ludwig and in 1908 the hardness was measured via the Adjustable Weight Bench Reviews differential depth. Based on the above basic concepts, two scientists Hugh M Rockwell (1890-1957) and Stanley P Rockwell (1886-1940) found a method to test Rockwell hardness and received a patent on July 15. / 1914.

♦ Rockwell hardness measurement applications
- Rockwell hardness is widely used for many details with different materials, sizes and shapes.
- On current hardness measuring machines, there is a system that converts to different scales with very high accuracy.

♦ Rockwell hardness measurement principles
- On Rockwell hardness gauges, we use a diamond gauge with a top angle of 120 degrees and a curvature radius of R = 0.2mm or a hardened steel ball with a diameter of 1/16, 1/8 , 1/4, 1/2 Inch for pressing against the test specimen surface.
- The hardness is determined by applying the ball or the diamond tip two successive forces, the initial force is 100N (called the primary force), the next force is 600N or 1000N or 1500N (called the force. secondary) according to the scale.
- The Rockwell hardness measurement procedure according to the diagram below, basically as follows: we apply the test head to the specimen with a minimum force, usually 10kgf or 30kgf if the material is soft. Once equilibrium is reached, the gauge will record the specified value (track head displacement and feedback on the depth of action of the probe. Second, while maintaining the dark actuation force minimally, the maximum force is applied, and these measurements are performed on a fully automatic hardness tester.
- When balance is reached, discontinue the maximum force while maintaining the original minimum force. When the maximum force is obtained, the indentation depth in the surface of the test piece is partially restored. The remaining indentation depth (the result of maximum force transmission and acquisition) was used to calculate the Rockwell hardness.
- Rockwell hardness is determined by a conventional quantity without dimension, depending on the depth of the indentation. The greater the depth, the smaller the hardness and vice versa.
- Initial applied force (primary force) L1, the measuring tip sinks deeply into the material 1 segment h, Next, we apply 1 force (secondary force) L2, the measuring tip sinks deeply into the material h2 section. The difference of the two tests is h - characteristic of the test material hardness.
- Rockwell hardness measurement unit has the symbol: HR, an HR unit corresponding to a settlement equal to 0.002mm.
Rockwell hardness is expressed by a conventional quantity depending on the depth h of the dent and determined by the formula:

HR = k - h / e

  + k: is a constant (using ball k = 130, using a diamond tip, k = 100)
  + e: is the value of one division of e. For hardness e = 0.002mm. For soft measurements also known as surface hardness e = 0.001mm
  + 0.002 or 0.001 is the value of the clock scale or when the gauge tip is pressed further 0.002mm or 0.001mm, the clock hand moves one bar.
  + h: difference of the depth of two presses (mm)

h = h2 - h1

- Depending on the applied force, Rockwell hardness is divided into 3 scales A, B, C respectively
- There are many Rockwell hardness scales, denoted by RA, RB, RC, ... depending on the type and size of the probe as well as the value of the applied force used.
- There are two divisions on the Rockwell hardness tester. Scale C, when tested with a diamond gauge with a pressure of 150kgf and scale B when using a diamond with a pressure of 100kgf. Ball (corresponding to scale B) is used to test the Rockwell hardness of hardened steel, copper, brass, ... and very hard materials must be tested with a diamond gauge as in the C scale, but With a pressure of 60kgf, read on a scale denoted by the letter A. Therefore, when writing the Rockwell hardness we must specify the hardness unit as: HRC, HRB or HRA

♦ In summary: Rockwell hardness measurement method
- Use a variety of measuring tips of different materials and shapes
- Measuring capacity: <150 kg
- Assessment based on the depth of the gauge
- Includes: 15 Rockwell Normal scales and 15 Surface Rockwel scales

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For further information and calibration requirements, Please contact

Equipment Inspection - Calibration - Repair Service Center - EMIN Vietnam JSC 

 Adress: No 11, Hoang Cau Moi Street, Trung Liet Ward Dong Da District, Ha Noi City

Email: - Hotline: 097.251.2864 (Mr. Truong)