What is a durometer?
The durometer as its name implies is a measuring instrument dedicated to testing and measuring the hardness of different types of materials. They are capable of measuring materials such as metals, plastics, rubbers, elastomers, among others.
Hardness is the property of materials that is defined as: resistance to permanent penetration under some static or dynamic load that material has.
How does it work?
The operation is based on exerting a load on the surface of the material to be measured through a penetrating element.
Once the object to be measured is selected, a type of hardness penetrator must be chosen (there are two types. A spherical steel ball and a conical one for the hardest objects). The durometer exerts a force on the surface which will leave a mark, once the load stops, the depth is measured. To know the hardness of the material.
Parts of a Durometer
Because there are different types of durometers, their composition may vary, but we can always find some main parts.
- Body: It is in charge of generating the load that is exerted on the material. All loads have to be standardized.
- Penetrating or indentation element: This is responsible for leaving the mark on the material.
- Indicator: As its name says, it is responsible for indicating the hardness obtained during the measurement process. This indicator also shows us information about what type of identifier to use.
Types of Durometers
We can find different levels of hardness and that is why for each of these there is a different durometer.
Its name comes from the fact that the scale of this instrument was defined by Albert Shore, Once the mark is left on the material. the depth is transmitted to a spring of a dial gauge, which gives us a certain value of hardness.
Rockwell hardness tester
This type is able to measure any metal or alloy. both hard and soft. Its method of operation is initially to exert a small load, which increases the accuracy of the measurement, and subsequently to exert a greater load.
Brinell hardness tester
This instrument is used with a hard penetrator in a spherical shape and the load is constant, the diameter of the footprint is measured with a microscope and converted to a specific number HB using a formula.
Vickers hardness tester
The fundamental principle is to observe the resistance of the material to deformation. This durometer is considered microhardness. The resulting footprint is measured with a built-in microscope and transformed to HV or DPH hardness using a formula.
These durometers incorporate an image analyzer through a computer which analyzes the location of the fingerprint, performs the operations of the hardness values and graphs the information obtained.
This durometer is similar to the Vickers, the only difference is that a much smaller sample is needed in the material to measure the hardness.
This instrument leaves a minor footprint to all the others since its operation is characterized by reading the energy loss in a defined impact after hitting the sample. Which means that this device generates an initial impact and when hitting the material impact energy is lost and this loss is measured to later convert it to hardness.