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The Automotive Industries Use Of AAV504 Automatic Vickers Hardness Testing System

When manufacturing automobiles and vehicle components, something that automotive companies have to take into consideration are the mechanical properties of components and this includes material hardness. Measurement of material hardness is essential to understand the properties of important components which will form a relationship to their service performance. Hardness inspections are introduced for control of manufacturing processes such as heat treatment processes which are used to optimise life and performance by modification of microstructures.

Material hardness is defined by the resistance to indentation and is determined by placing a precise and fixed load onto an indenter(the indenter is 136 degree square pyramid), which is then placed on top of a material or component and a load applied for a time period of 8 to 15 seconds. The indenter then creates a permanent indentation of which the size is measured by calculting D1 and D2 using the eyepiece ocular which can measure to an accuracy of 0.1 micron. The smaller the indentation created, the harder the material.

Although there are many different hardness tests, the Vickers hardness test is most commonly used in the automotive industry. The vickers test is used due to the accuracy and precise positioning of the indentation. This allows for measurement of microstructural phase or case profile measurements to show the effective hardness measured into the component carried out on a prepared cross section.

What is the Vickers hardness test?

Smith and Sandland developed the Vickers hardness test in 1924. Like the Brinell test, it evaluates hardness in a similar manner – by taking the ratio between the load applied and the surface area of the resulting impression. The resulting measurement is known as the Vickers Pyramid Number. This is the measurement of the size of the resulting impression created by the applied load on the indenter on the material being tested.

Load can be adjusted to suit the component being tested and results can be directly compared, see information taken from the ASTM specification.

The Vickers indenter usually produces a geometrically similar indentation at all test forces. Except for tests at very low forces that produce indentations with diagonals smaller than about 25 μm, the hardness number will be essentially the same as produced by Vickers machines with test forces greater than 1 kgf, as long as the material being tested is reasonably homogeneous. For isotropic materials, the two diagonals of a Vickers indentation are equal in size. Recommendations for low force microindentation testing can be found in Appendix X5.

The Vickers indenter is a diamond square-based pyramid.

The Vickers indenter is a square-based pyramid made from diamond with an included 136° angle. It was designed to overcome some of the problems related to the Brinell tests’ spherical indenter. The benefit of using a diamond square-based pyramid indenter is that it is capable or producing geometrically similar impression, irrespective of size and that the resulting impression has well defined points for easy measurement.

The unit of hardness given by the test is known as the Vickers Pyramid number and is determined by the ratio force applied to the indenter divided by the surface area of the resulting indentation.

Many manufacturing businesses in the automotive industry prefer using the Vickers hardness test because it is easier to use than other hardness tests and more suitable For thinner materials or smaller components. It also produces calculations that are independent of the size of the indenter and can be used to test a wide range of materials including all metals and some ceramics.
The AAV504 Automatic Vickers hardness testing system is fully automated allowing automotive manufacturers to carry easy and efficient hardness tests.

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The AAV504 Automatic Vickers Hardness testing system

One of the main benefits of using the Automatic Vickers Hardness Testing system is that it allows for the increased accuracy of metal hardness measurements. Whereas in the past, automotive companies would have to look up tables to find the Vickers hardness number of a material, today they can simply check the testing system’s digital encoder. The AAV504 Automatic Vickers hardness testing system has a built-in calculator that not only gives an accurate Vickers hardness number, but also scale conversions and statistics too.

Whereas early generations of Vickers hardness testers required the operator to use a foot pedal to operate the test force was to the indenter, the AAV504 Automatic Vickers Hardness testing system is completely computer controlled. This means that technicians are free to use them time more wisely on other tasks whilst the hardness test is being carried out. Hardness testing patterns can be programmed into the VL Pack software automating the setting up of advanced hardness analysis offer great time saving benefits.

Quality control

The AAV504 Automatic Vickers Hardness testing System is used widely by manufacturing businesses in the automotive industry for quality control purposes. Using the automatic hardness tester, they can determine the hardness of a wide range of metal-based parts including alloy wheels, engine parts, cylinder heads and gears. Determining the hardness of the materials used to make these components provides automotive manufacturers with valuable insights to the durability, strength, flexibility and capabilities of their components.

By optimising the hardess of the components, the stronger and more durable they will be, preventing them from having to be replaced as frequently, resulting in a higher quality automotive design and improved performance. Manufacturers work to stringent specifications which control the mechanical properties to produce standard components of high quality.
The quality control process carried out by the automotive industry also involves testing the hardness of components in relation to safety. The harder the components used to make up a vehicle, the stronger and safer they will be if impacted.

For more information about the AAV504 Automatic Vickers Hardness testing system and how it can benefit businesses operating in the automotive industry, feel free to get in touch with us here at Spectrographic.

Image credit: CORE-Materials