In the precision machining industry, there are a good number of aspects to consider in order to achieve the best possible results. Otherwise…
In a recently started survey among LinkedIn users, we asked different professionals whether they used hardness testers in their work.
So far, we have received 126 answers described here below:
33% used them in the past.
Of course, hardness testers are not all the same. And each of them is suitable for a specific application. We invite you to keep reading to learn more about these non-destructive testing instruments. Click here to check the Linkedin survey.
What are hardness testers?
As defined by the famous encyclopedia Britannica, a hardness tester is a “device that indicates the hardness of a material, usually by measuring the effect on its surface of a localized penetration by a standardized rounded or pointed indenter of diamond, carbide, or hard steel.”
In simple words, hardness testers are non-destructive testing instruments that allow you to determine, based on the applicable standard, the value of hardness of different materials, including, but not limited to:
- Steels and steel alloys
- Aluminum and aluminum alloys
- Thermoplastic elastomers
How is hardness measured?
The typical hardness test involves an object called indenter which is pressed on and into the surface of the material being tested.
The indenter must have specific dimensions and must be loaded with a specific pressure depending on the type of tester.
Afterwards, the hardness is determined by measuring the depth of the penetration or the area of the indentation. Measuring one or the other will depend on the type of hardness test being performed. The most common ones are:
- Leeb hardness test
- Rockwell hardness test
- Vickers hardness test
- Brinell hardness test
- Shore harness test
Why is hardness testing so important?
Knowing the hardness of the materials used in a workpiece or structure is important for different reasons. First of all, hardness testing allows you to assess important properties such as strength, ductility and wear resistance.
Therefore, with the information obtained it is easy to determine whether the material is suitable for the application in hand or not and whether further surface treatment is necessary to achieve the desired results.
Also, it can be used to verify the quality of the material and determine if maintenance is required.
What are the different types of hardness testers?
As it was mentioned above, there are different hardness testers for different applications. So, let’s take a look at the most common ones.
Leeb Hardness Testers
As the name suggests, these testers are based on the Leeb hardness test as defined in the ISO 16859 and ASTM A956 standards. It is a dynamic test method where the ratio of rebound velocity to impact velocity of a moving impact body is used to determine the hardness.
Leeb hardness testers are usually applied for testing various metals and alloys, and they are a great choice when checking incoming and outgoing goods, for quality control activities, and maintenance of structures and workpieces subject to wear.
Here at SAMA Tools, we offer 3 different models of Leeb hardness testers:
- Leeb hardness tester SAP180, with D type impact probe and a test block.
- Touchscreen Leeb hardness tester SAP550, with the touchscreen display and a wireless printer for printing reports on the go, which is great for quality control activities on the field.
- Pen type Leeb hardness tester SAP650, a compact and highly accurate tester with automatic detection of impact direction and wireless interface.
Barcol Hardness Testers
Similar to the previous type, these instruments are named after the hardness test that they perform, the Barcol test.
This test is usually applied on softer materials such as aluminum, aluminum alloys and some plastics. It was previously known as Barber-Colman Impressor since Walter Colman developed this test as a portable method during the World War II.
The process uses the indenter or “impressor” to press on the material and measure how deep the tip of it penetrates.
We offer 2 models of Barcol hardness testers:
- Analogue Barcol hardness tester
- Digital Barcol hardness tester
Webster Hardness Testers
This simple model of hardness testers allows to measure the hardness of soft materials such as soft steels, aluminum, brass and copper. Moreover, it can be applied on different geometries and very small thickness values.
The values obtained can be easily converted to the common scales, including Vickers, Rockwell and Brinell.
We offer 3 versions of the Webster hardness tester:
The main difference is the range of thickness and diameter they can be applied on.
Shore Hardness Testers
Shore hardness is defined as the resistance of a material to penetration of a spring-loaded needle-like indenter.
By using the definition, we can easily conclude that the process to perform a hardness test with a Shore hardness tester is very similar to the one with the Barcol tester.
There are different scales for Shore testing being the most common ones the Shore A scale for soft elastomers like rubber, and Shore D for hard elastomers and other polymers like thermoplastics and thermosets. This makes Shore hardness testers a great option for quality control activities in rubber and plastics industries and for maintenance checks on ring nuts and gaskets.
We offer 3 different versions of the Shore hardness testers:
- Analogue Shore Hardness Testers
- Digital Shore Hardness Testers
- Pro Digital Shore Hardness Testers
The last one in the list is the most powerful of all, since it can handle more than the two scales mentioned above, and it comes with many other interesting features.
We also offer special stands for more accurate and repeatable results, and Shore test blocks for verification and calibration purposes.
Bench Hardness Testers
The most specialized hardness testers in the market are usually bench hardness testers, since they offer a higher accuracy and repeatability. Therefore, they are the favorite option for metrological laboratories and applications which require the maximum of these two aspects.
These testers work with the indentation principle by applying a constant load over a specific period of time on an indenter which is in contact with the sample. They can use indenters of different sizes, shapes and materials, thus providing the possibility to work with different standards and scale on the same device.
We offer 5 versions of bench hardness testers, some of them manually operated and others which are motorized. The versions are:
- SAB150-B which is manual, analogue and ready to work with Rockwell A, B and C
- SAB150-BM which is motorized, analogue and ready to work with Rockwell A, B and C
- SAB150-B/DGT which is manual, digital and ready to work with Rockwell A, B and C
- SAB150-BM/DGT which is motorized, digital and ready to work with Rockwell A, B and C
- SAB187,5-B which is motorized, analogue and ready to work with Rockwell A, B and C, Brinell and Vickers hardness scales. It comes with a microscope.
All of our bench hardness testers come with a diamond cone indenter and their corresponding test blocks.
So, which hardness tester is used the most?
According to the survey, most of the respondents who claim to use it or have used it say they have used the bench hardness tester. This is followed by users of shore hardness tester and Leeb hardness tester. Last but not least, the Webster and Barcol hardness testers.
The sample stated that the purpose of the use was:
- Inspection of workpieces after hardening to ensure durability.
- Control of incoming goods.
- Recognizing the hardness of the material to be welded.
How can I select the best hardness tester for my application?
When selecting the best hardness tester for your application, there are different things to consider. The most important are:
- Type of material tested
- Requirement of standard compliance
- Material approximate hardness
- Sample size and geometry
- Mounting requirement
- Number of samples to be tested
- Required accuracy and repeatability
If you want to check the hardness testers that we offer to select the one for your application, just click here.
Of course, if you are not sure yet or have any doubts about hardness testers, our recommendation is to contact us and one of our experts will gladly help you.
Video summary: Portable or bench hardness testers? The challenge