Hardness Testing: Blocks and Indenters Guide

Inaccurate material hardness readings from a faulty hardness testing machine can lead to serious operational failures. 

We've been in this industry long enough to see the consequences, and they are always costly. Your operation needs data you can depend on, which means your equipment must be providing consistently correct measurements. 

So, let's focus on the two components that directly impact your results: the test block and the indenter.

What is a Hardness Tester Test Block and Why is it Essential?

Consider a hardness tester test block the definitive standard for your machine's accuracy. 

It's a precisely engineered piece of material, a certified reference block, with a hardness value that is certified to be correct. You use this block for the critical process of hardness test block calibration and verification. 

Our product line, from the Rockwell Test Blocks to the Brinell Test Blocks, serves as that reliable benchmark. From our standpoint, operating a hardness tester without routine verification introduces an unacceptable level of risk into any quality system.

For businesses involved in sectors like aerospace or automotive manufacturing, where component failure is not an option, this check isn't just a suggestion—it's an essential procedure. 

For instance, an aerospace supplier must guarantee that a landing gear component meets a specific Rockwell hardness test value. Regular verification with an HRC test block is the only way for them to prove their tester's readings are valid and that the component is safe for service.

The Hardness Testing Procedure for Accurate Verification

Having a test block is one part of the equation; using it correctly is what ensures data integrity and hardness testing accuracy. This verification process is straightforward, and we feel it should be a non-negotiable part of your quality control routine.

1. Select the Proper Block: If you are performing a Superficial Rockwell test, for example, you would choose a Superficial Rockwell HR15N block. The block must match the specific application.

2. Prepare the Surfaces: Confirm that your tester's support anvil and the surface of the block are completely clean. Any foreign material can skew the reading.

3. Conduct the Test Sequence: Place the block firmly on the anvil. Let the machine apply its force to make an indentation. We advise making at least five indentations in different areas to establish a valid average.

4. Analyze the Results: Compare the average of your readings to the value on the block's certificate. If they align, your hardness testing machine is performing correctly. If not, it may require professional service.

Related article: Choosing Your Hardness Test & Getting Accurate Results

What is an Indenter in a Hardness Test?

The indenter is the component that executes the actual test. This is the critical point of contact where the machine meets the material. 

An indenter that is out of specification, whether from wear or poor manufacturing, will produce unreliable data. The performance of our Diamond and Ball Penetrators is something we stand behind for this very reason.

Related article: Guide to Micro and Macro Hardness Testing

Matching the Indenter to the Hardness Test Scale

Using the correct diamond indenter or ball indenter for the material and test type is fundamental to achieving a valid result.

- For a Rockwell Hardness Test: Valued for its speed, this test is run on machines like our HardRocker™ 150-A. They use a diamond cone for harder materials or a tungsten carbide ball indenter for softer ones. This makes it the workhorse for quickly checking parts like an automotive gear or a ball bearing.

- For a Brinell Hardness Test: When you are assessing materials with coarser grain structures, testers like our QualiBrineller series are the appropriate choice. They use a larger carbide ball to get a more representative measurement. Think of verifying a large iron casting for industrial machinery, where a small test point wouldn't tell the whole story.

- For a Vickers Hardness Test: When testing very thin materials like coatings, precision is key. This microhardness test uses a pyramid-shaped diamond indenter to make a minute impression. A perfect use-case is measuring the hardness across the heat-affected zone of a weld.

For situations requiring measurements outside the lab, a portable hardness tester like the QualiTip Plus Leeb tester provides the reliable on-site data our clients require.

Qualitest: Your Partner for Dependable Hardness Testing

In a competitive market, your company's reputation is built on the quality and reliability of its products. Inaccurate hardness data can lead to product failure. Investing in quality testing equipment—from a versatile Analog Rockwell Hardness Tester to the proper test blocks and indenters—is a direct investment in your company's reputation.

At Qualitest, we offer more than just equipment; we provide solutions. We have a full range of hardness testers, from our portable QHR-Series to our benchtop systems, that are both effective and budget-conscious. Our team is here to help you select the precise tools you need to meet and exceed your quality objectives.

Ready to improve the reliability of your hardness testing? Review our collection of hardness testers and the essential hardness test blocks and indenters. Contact us today to discuss how our cost-effective products can help you achieve your quality goals.