Product Overview
Mitech MHRS-150 Digital Rockwell Hardness Tester, based on the mechanical principle of conical diamond or hard alloy indenter pressing into the sample surface to produce indentation, realizing the material hardness measurement by measuring the depth of the indentation. Capable of inspecting the finished or semi-finished parts of the machined sample, it is suitable for high accuracy hardness testing for batches parts with various metal or non-metallic materials. According to statistics, Rockwell hardness testing is the most widely used hardness testing method in metal processing industry, which utilization ratio is more than 70%. With novel appearance, stable performance, intuitive and convenient LCD display, and easy to operate the menu design, it is widely used in metal processing and manufacturing, various metal material’s failure analysis and other fields like colleges and research institutions. It is the new type Brinell hardness testing instrument for testing the hardness of the materials like cast iron, steel, soft alloy and so on.
Function & application
l Used for quality control in metal processing manufacturing
l Used for failure analysis testing of metallic materials;
l Demonstration experiment for education and teaching in Colleges and Universities;
l Hardness testing of materials in scientific research institutions
Working Principle
The Rockwell hardness test is taking the diamond cone with 120°apex angle or the hardened steel ball with specified diameter as the indenter to press into sample surface with specific test force, then get the Rockwell hardness of the measured metallic materials according to the sample surface indentation depth.
The Rockwell hardness measurement principle is shown as below figure. 0-0 is the position that the diamond indenter is not yet in contact with the sample. 1-1 figure is the indenter position under the affect of the preliminary test force, the indentation depth is h1. The preliminary test is to eliminate the influence to the testing result accuracy caused by the roughness of the sample surface. 2-2 in the figure is the indenter position under the influence of the testing force (the preliminary test force and the main test force). The depth is h2. 3-3 in the figure is the indenter position after dismounting the main test force. As the metal elasticity will recovery some degree after deformation, the really indentation depth of the indenter is h3. The plastic deformation caused by the main test force make the indenter pressing into the depth is h＝h3－h1. Rockwell hardness value is determined by the size of h, the greater the depth h, the lower the hardness, otherwise, the higher the hardness.
In the traditional concept, usually use a constant C minus h to represent the level of hardness, while the depth of indentation per 0.002mm as a unit of hardness. The hardness value obtained is called the Rockwell hardness value, denoted by the symbol HR.
In the formula, c is a constant (for HRC, HRA, c is 0.2; for HRB, c is 0.26). The Rockwell hardness value HR obtained is an unknown number which is usually read directly on the test machine indicator when testing.
It should be noted that the measured hardness values would be different with different indenter and test force. Therefore, the Rockwell hardness testing specifies 15 different hardness test scales according to the different indenter
specification and test force sizes. And the HRB, HRC, HRA are the most widely used.
Working Conditions
l Operation Temperature：10～30℃；
l Relative Humidity：≤65％；
l The surrounding environment should avoid of vibration, strong magnetic field, corrosive medium and heavy dust
Instrument Features
l Widely used for high-precision hardness testing for parts with a variety of metal and non-metallic materials；
l Option for various specifications of the indenter, support 15 types of Rockwell hardness scales testing;
l Equipped with high-speed thermal printer, it can quickly print out the test data;
l Support the conversion among various hardness scales such as Brinell, Vickers and etc;
l Adopt large-screen LCD, easy to operate, visually display the test results;
l Adopt diamond indenter, durable and accurate measurement;
l Use grating displacement sensor, and the indentation depth measurement error is small;
l With the error value correction function, the hardness value of the error can be corrected by key input, making the
hardness value more accurately meet the test requirements;
l With the function of threshold overrun automatic alarm, which applies to the bulk of finished products or semi-finished
pieces of paper-by-piece detection;
l The function of original ambient temperature real-time display can avoid the instrument working in the case of high or low
temperature for a long time , resulting in increased test error and reducing the service life;
l Consistent with EN-ISO-6508、GB/T230.1、GB/T230.2、JJG112、ASTM E18 and other relevant standards at home and
abroad.
Instrument Maintenance
l The test personnel should follow the operating procedures.Before and after the test,it should be repeated with standard
block calibration equipment;
l If the specimen has visible deformation marks on the back and edges, the test result would be useless. It should choose
the intender or test force to test again;
l Normally, the first point is only used to offset the gap of each support surface without needing to record the test result.
Record the statistical test result from the second point;
l During testing, to ensure accuracy, please make sure the distance between the adjacent indentation center and the
distance from the indentation center to edge of the specimen is greater than 3mm;
l Pay attention to palm the instrument for carrying to forbid falling across. Please fix well the measuring lever, counterweight
and boom before carrying;
l It is strictly prohibited to turn the variable loading handwheel when the instrument load or unload the test force. Rotating
the handwheel forcibly will cause the internal gear dislocation, test force in chaos and even damage the internal parts of
the instrument;
l Turn off the power after using the instrument;
l When not in use for a long time, please cover the dust cover to prevent dust into the instrument interior. And the
hardness block, indenter should be coated with antirust oil to prevent rusting after using;
l Long time after the re-enabled,it should be preheated the electrical components before test
l The hardness tester should be calibrated at least once a year to ensure its accuracy.
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