How to Choose a Suitable Leeb Hardness Tester.

Leeb hardness tester is a metrological and testing instrument, which plays an important role in ensuring product quality and conducting failure analysis. Therefore, choosing a good Leeb hardness tester is a key issue for users.

1. Choose imported or domestic Leeb hardness tester?

Proceq, a Swiss company, invented the Leeb hardness tester in 1977. The Leeb hardness tester produced by the company is world-class. At present, many countries in the world use the company’s technical standards as their own metrological standards. China’s national metrological standards are also formulated with reference to the technical standards of Proceq. The main feature of the Leeb hardness tester produced by Proceq, a Swiss company, is that one host can be equipped with seven different types of impact devices. The performance of imported Leeb hardness testers is impeccable, but the price of imported Leeb hardness testers is relatively expensive. It costs about RMB 80,000 to buy an imported D-type standard configuration Leeb hardness tester, and it is inconvenient to repair if there is a problem. The characteristic of domestic Leeb hardness testers is that they are cheap. It costs about RMB 10,000 to buy a domestic D-type standard configuration Leeb hardness tester. However, domestic Leeb hardness testers have advantages and disadvantages, so you must choose carefully when purchasing.

2. How to identify the quality of Leeb hardness tester?

The real Leeb hardness tester is in line with national and international standards and has interchangeable consistency. Although the relevant Chinese departments have formulated the national standard for Leeb hardness tester, some manufacturers have adopted the correction method to produce Leeb hardness tester because their technical strength is not up to the level of producing Leeb hardness tester that meets the standard. Although their products are also called Leeb hardness tester, they are far from the real Leeb hardness tester. The hardness tester with inaccurate measurement value can also meet the requirements of accurate test hardness test block after correction. Therefore, users need to pay attention to the following characteristics of the real Leeb hardness tester to choose a good Leeb hardness tester:
① The impact device is interchangeable. One host of Leeb hardness tester can be equipped with seven different types of impact devices at the same time; several impact devices of the same type can be configured on one host.
② The punch of the impact device is replaceable. The punch of the Leeb hardness tester impact device is replaceable. The punches of the same type of impact device can be replaced with each other without affecting the measured value.
③ The Leeb hardness tester is not adjustable. The Leeb hardness tester is not adjustable after leaving the factory. When the measured value is inaccurate due to the wear of the ball head, the ball head should be replaced.
④ The measurement error of the Leeb hardness tester meets the standard requirements in the entire range of hardness. The measurement error of the Leeb hardness tester meets the error requirements specified in the standard in the entire range of hardness from low to high.

3. How to choose a suitable Leeb hardness tester for yourself
   ① Understand the specifications of the workpiece you need to test, as well as the size, thickness, surface roughness and other physical properties of the workpiece.
   ② The material of the workpiece will also have different effects on the test results. For example, special materials such as aluminum, copper, and tool steel have different rebound moduli of different materials. The choice of impulse device is extremely important for the test results.
   ③ The purpose of purchasing the Leeb hardness tester is to test the hardness system, HL, HB, HRC, HRB, HV, HS. If the above conditions are met, you can purchase a Leeb hardness tester that improves your work efficiency.
4. Calibration of Leeb Hardness Tester
   Leeb hardness tester has been widely used in the world due to its convenient portability, simple operation, rapid detection and accurate measurement. Due to people’s habits and the hardness measurement standards that have been used for many years, Brinell, Rockwell, Vickers and Shore hardness test methods are still commonly used in actual hardness testing. Leeb hardness test method has only appeared in the past 20 years. It will take some time to use Leeb hardness test method directly for hardness testing. At present, in order to take into account the practicality of Leeb hardness tester and the requirements of traditional hardness measurement standards, and to meet the needs of hardness testing, people often have to convert Leeb hardness value into Brinell, Shore, Rockwell and Vickers hardness values. Whether Leeb hardness value can be directly converted into other hardness values ​​is related to the impact device used and the hardness material being tested. Establishing the conversion relationship between different hardness values ​​often requires people to do a lot of work.
5. Standards for Leeb Hardness Tester
   Leeb hardness tester has been widely used in the detection of metal hardness due to its convenient portability, simple operation, rapid detection and accurate measurement. The relevant national departments have also successively promulgated a series of standards for Leeb hardness tester. The following is a brief introduction.
6. “Technical Conditions for Leeb Hardness Tester” ZBN 71010-90
   This standard belongs to the industry standard. It stipulates the technical conditions, test (inspection) methods, inspection rules, completeness and marking, packaging, random documents and other contents of Leeb hardness tester.
   Standard regulations:
7. The hardness tester should work normally under the following conditions:
   Ambient temperature 0~40℃, relative humidity not more than 90%;
   The surrounding environment has no vibration, strong magnetic field, and corrosive medium.
8. The hardness of the tungsten carbide ball on the punch should not be less than 1500HV.
9. Error:
   The relative error of the indication shall not exceed ±0.8%;
   The relative error of the indication repeatability shall not exceed 1%.
10. The conversion error between Leeb hardness and Brinell, Rockwell and Vickers hardness is shown in the table below (E=210000N/mm2)
11. The hardness tester supplied as a set shall include: · Impact device; · Display device; · φ90×55 hardness block equivalent to 800±50HL Leeb value.
12. “Leeb Hardness Tester” J J G 7 4 7 – 1 9 9 9
    This standard belongs to the national metrological verification regulations. The regulations outline the test principle of Leeb hardness tester, the technical parameters of the impact device, the technical conditions of Leeb hardness tester, the verification conditions and the hardness conversion comparison value. The main features of the regulations are:  The main technical parameters of various types of impact devices are given. The technical requirements of the standard Leeb hardness block are specified. The conversion values ​​of Vickers hardness and Leeb hardness on standard test blocks are given. The conversion values ​​of Brinell hardness and Leeb hardness on standard test blocks are given.
    III. “Metal Leeb Hardness Test Method” GB/T 17394-1998
    This standard is the latest national standard. The standard specifies the test principle, symbols, specimens, test instruments, tests, test result processing and test reports of metal Leeb hardness test. The main features of the standard are: the main technical indicators of the specimen are specified, including: surface roughness, weight, minimum thickness, minimum surface hardening layer depth and minimum curvature radius. The test method for Leeb hardness test of the specimen is explained. The conversion table of Leeb hardness and other hardness for various materials is given, including: carbon steel, cast steel, cast iron, low alloy steel, cast aluminum, copper-zinc alloy, copper-tin alloy, pure copper.
13. Conversion values ​​of hardness and strength of ferrous metals GB/T 1172-1999
    This standard is a national standard. The standard lists the conversion values ​​of hardness and strength of ferrous metals, including the main steel systems: stainless steel and carbon steel, chrome steel, chrome vanadium steel, chrome nickel steel, chrome molybdenum steel, chrome nickel molybdenum steel, chrome manganese silicon steel, and ultra-high strength steel.
    The conversion data of Leeb hardness and strength attached to the Leeb hardness tester is obtained according to this national standard.
    In 1984, TIME Group was the first domestic company to independently develop and manufacture Leeb hardness tester products. For more than 20 years, its products have been distributed in all walks of life across the country. The conversion data tables provided to Chinese users are in line with the above national standards; the conversion data tables provided to foreign users are in line with international standards.