Durometer

November 1, 2021

The durometer is an instrument used to measure the hardness of materials . Hardness is a property of bodies that indicates their resistance to deformations caused by external forces, such as perforations, scratches, abrasion and any type of damage that the material may suffer.

Hardness has different scales and ranges, so the tip used to make the measurement and the loads that are applied vary. The hardness of some materials, such as steel, has a relationship with mechanical resistance and, therefore, the durometer is often preferred by industries to perform tests on materials.

What is the Durometer?

The durometer is the instrument used to determine the hardness of materials. It works by delivering a charge to the material to be measured with a penetrating pointed object. Basically, the durometer exerts a force on the material to be measured, drilling with its tip and depending on the depth of the drilling, the hardness measurement is obtained.

The durometer design varies depending on the model. There are pocket durometers to table durometers, which weigh 100kg, but always, regardless of the model, it has two fundamental parts; body and piercing point. In the body it has the indicator screen and controllers to calibrate the durometer.

What is the Durometer for?

The durometer measures the hardness of materials, its usefulness and function is quite specific. Knowing the hardness of materials is necessary to be able to classify them and use them later for the realization of tools and artifacts. Hardness indicates the resistance that the material presents to external forces.

Durometer uses

The main use of the durometer is in the industries, which is where it is required to know all the properties of the materials that are going to be used; the two main ones are pharmaceutical and metal , the latter to ensure that the established safety parameters are met. Also due to the relationship between the hardness of steel and its strength, many prefer to opt for the hardness test because of its simplicity.

In the pharmaceutical industry it is also commonly used, mainly to measure the hardness of capsules and pills. They must be hard enough to withstand packaging, transfer and various processes without being damaged but soft enough to be chewed or easily digested, so they maintain regulatory controls on their hardness.

Types of Durometers

Remember what I mentioned about the different hardness scales? Well, for each scale, all of them for industrial use by the way, there is a corresponding durometer, with its particular design and although they all work with the same principle; It is essential that you know the differences between the hardness scales and the types of durometers:

  • Durómetro Shore

This measures the elastic hardness of the material . Instead of creating a small perforation test the elastic resistance when pressing the material. For this, a scleroscope is used which consists of a tube with an internal diamond-tipped hammer that will test the resistance. This durometer is used in testing materials such as rubber.

  • Brinell Durometer

It is used to calculate the tensile strength. It is not that precise and uses the indentation method; It has a circular steel tip to make the impression, the resulting fingerprint is measured under a microscope and transformed to an HB figure. This test is used on soft materials as their plates are less than 6 mm thick.

  • Durómetro Rockwell

The most widely used due to its ability to measure both soft and hard materials and its level of precision. This uses a diamond cone point and generates two charges, the first light and the second with greater force. The imprint printed on the material is minimal, it does not pierce it, so it is not considered a destructive method.

  • Durómetro Button

It has the ability to measure hardness, taking into account absolute scale values. It has a diamond tip and measures mechanical hardness; it actually measures “microhardness” as it works with very small samples whose plates are thin, exerting a standard force on them. Its design and calibration is specially designed for small samples.

  • Durómetro Vickers

Known as the universal hardness test, its loads range from 5 to 125 kiloponds (the kilopond being the old unit of force). It has a conical diamond tip, it is more accurate than the Brindell model but like that, it does not give the reading directly but must be transformed with a formula. It is used in sheets of about 0.15 mm thick.

  • Leeb Durometer

It reads the loss of energy when impacting with the material , so it does not leave a deep sample being a non-destructive test. This loss of energy is then transformed to be able to measure the hardness of the material.

The different types of durometers are due to a process of improvement that has taken place over the years; where for example Knoop’s is a variation of Vickers’ for small objects. In addition, the use of the durometer there are certain tests to measure hardness such as nanoindentation, which is carried out in nanometric lengths.

Durometer Features

The various types of hardness testers have different designs; This is because, for example, a tabletop durometer is not needed for one that would only be dedicated to measuring small and light objects. This can make it difficult at first to distinguish them from other instruments, so I name the following characteristics that are invariable:

  • The body is the main structure, in it the elements that make it work are attached both externally and internally.
  • The tip is the oval or conical part that can be made of steel or diamond; It is the one that generates the load on the material, be it light or strong.
  • The indicator is the screen where the measurement reading appears.
  • The work panel is used to calibrate the durometer.
  • The work platform is only possessed by table durometers, it is where the sample is located to keep it in position during the procedure.

Rockwell, Brinell, Vickers, and Knoop durometers are bench-top, and have parts like the winch to move the work platform, the screw to adapt the indenter, and the force transformer. While the Shore and Leeb durometers are much more discreet, the first mechanical and the second electrical.

Importance of the Durometer

The durometer is widely used in various sectors. Knowing properties such as the hardness, resistance and elasticity of a material is essential to be able to use it, otherwise it would represent a huge security risk since there would be only vague and inaccurate estimates of what a certain material can resist or for what types of use it is suitable.

The studies of materials with durometers are sometimes supported with other instruments and it is that each of these is needed to be able to know all the properties of the elements that we use.

Dr. Loony Davis5
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Born and raised in Brussels in an English family, I have always lived in a multicultural environment. After several work experiences in marketing and communication, I came to Smart Water Magazine, which I describe as the most exciting challenge of my career.
I am a person with great restlessness and curiosity to learn, discover what I do not know, as well as reinvent myself daily, someone who is curious about life and wants to know. I enjoy sharing knowledge.
This is my personal project but I also collaborate in other blogs, it is the case, the most important web on water currently exists in the US, if you are interested you can read my articles here.

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