The Basics of the Rockwell Scale

Ordinary versus superficial

• The Rockwell technique has a very simple idea at its core. The sample material is initially set up on the tester, and a small load is applied as the zero point.
• The principal load would then come after that, using force and an indenter with a diamond tip to make the indentation. The operator determines the strength of the material by measuring the depth of the indentation formed after a few minutes of pressing on the material.

In reality, there are two separate kinds of Rockwell test procedures. The Regular method and the Superficial method are these. The Regular technique is often referred to as the Rockwell method (AKA Super Rockwell method).

1. The Usual Approach

Since this is how the Rockwell test is often conducted, 10 kgf is always the initial force or load applied to the machine. The principal force or principal load could be 60, 100, or 150 kgf.

When evaluating bulky or oddly shaped materials, the Regular Approach is preferred. It is no longer required to cut the specimen into pieces or polish it to have a smooth surface because the depth of the indentation is more important in this test.

It would be excellent to identify the materials you need to test, together with their typical sizes and shapes, before searching for a device for the conventional way (the latter matters only if the material is prefabricated). You can purchase a Rockwell Hardness Testing device from a reputed manufacturer that can handle samples of various sizes, shapes, and kinds.

2. The Simplistic Approach

This approach is the “lighter” version of the exam, as the name suggests. In reality, this particular variation of the procedure was created to examine the hardness of thin or small parts, including bolts, minor joints, and material treatments. Even materials whose hardness rating frequently falls beyond the Normal Rockwell scale can be tested using this method.

This variant’s initial load is 3 kgf. The primary load is determined by the size, thickness, and shape of the material and is available at 15kgf, 30 kgf, or 45kgf.

The hardness values for the regular and superficial Rockwell techniques are compatible despite these distinctions. Even capabilities that enable an operator to translate these values instantaneously may be built into a Rockwell Hardness tester by the manufacturer.

Making use of the Rockwell Scale

Many iterations of the Regular and Superficial tests have been developed in order to make the Rockwell approach suitable to various industries. These procedures are very different from one another because

• The different kinds of indenters employed. The Diamond Hardness Test is another name for any scale that employs a diamond indenter.
• Amount of the total test load; B; scale division; and C.

The regular and superficial varieties each require the application of nine separate Rockwell scales.

i. HRA – This scale utilizes a 120° diamond spheroconical indenter along with a 6-kgf major load. Usually, it is used with substances like tungsten carbide.

ii. HRB – This scale is used to test aluminum and other softer steels. It uses a 1/16-inch steel sphere.

iii. HRC – For this scale, a diamond indenter is used to apply 150 kgf to heavy steel materials.

iiii. HRD – The material is subjected to a primary load of 100 kgf while a 120° diamond spheroconical indenter is used.

v. HRE – A steel sphere indenter will be used instead of the 100 kgf applied to the material on Scale D.

vi. HRF – This scale uses a 1/8-inch steel sphere indenter with a total force of 60 kgf.

vii. HRG – This scale applies 150 kgf to the material while using a 1/8-inch steel sphere as the indender.

viii. HRH – With a steel sphere indenter that applies a total of 60 kgf, this scale is frequently used to test materials such as aluminum, zinc, and lead.

ix. HRK – The final scale in the Rockwell series of tests, Scale K administers 150 kgf to a steel spherical indenter. This test is frequently applied to materials like plastic, tin, and alloy.

Should There Be a Break

A hardness test’s immediate result is that you will eventually get to the material’s breaking point. Even tests when the specimen breaks shouldn’t be written off as a waste of time.

In the event that a material does fracture under the load, a Rockwell Failure Analysis must be performed right away. This procedure is intended to make it easier for the operator to pinpoint exactly when and why the material broke throughout the test.

A trustworthy manufacturer of Rockwell hardness testers will include instructions for performing a failure analysis with each of their products, including information on what to look for and when. If done correctly, the study can point you in the direction of a superior substitute material for testing or production cycles in the future.