Considerations for Selecting a Hardness Tester

Considerations for Selecting a Hardness Tester
When selecting a hardness tester for your application, it is important for you to consider the following:

Choose the correct test method based on the application.
Plan to use the highest test force and largest indenter possible. Consider the effects of the shape and dimensions of your test sample.

Answer these key questions:
1.  Does your test prescribe a specific hardness scale to be used?
2.  What is the material to be tested, and is this material suitable to the type of test method you are considering?
3.  How large is the part, component or specimen to be tested?
4.  Is the test point difficult to reach?
5.  What is the volume of testing that will be done?
6.  How accurate does your test result need to be?
7.  What is your budget?
8.  What is the required return on investment and do you have ways to measure reductions in costs- yields, throughput, operator efficiency?
9.  What testing problems have you experienced in your current method?
10. How knowledgeable are the users of the tester?

Verify the test results meet your requirements for accuracy and repeatability.
Consider performing a Gage R&R to gather quantifiable data on how much error is attributed to the operator and the measurement system employed.

There are significant differences between levels of performance within each classification of tester. A difficult job on one tester could be very simple and fast on another. So, although hardness testers within a test method and classification look alike, there are many features that can significantly affect productivity and accuracy. A good example of features affecting performance is demonstrated in bench Rockwell hardness testing systems. All can handle moderately long parts using larger anvils or jack rests, however the Versitron Series can usually test large parts more quickly and accurately, when compared to other bench testers, which require external support stands or fixtures. The Indentron Series, on the other hand, is much easier to use on small, awkward parts.
 
Test Type

Test Method

Test Force Range

Indenter Type

ASTM Reference

Measure Method

Rockwell

Regular

60, 100, 150 kgf

Conical Diamond & Small Ball

E 18

Depth

Rockwell

Superficial

15, 30, 45 kgf

Conical Diamond & Small Ball

E 18

Depth

Rockwell

Light Load

3, 5, 7 kgf

Truncated Cone Diamond

Informal

Depth

Rockwell

Micro

500, 1000 gf

Small Truncated Cone Diamond

Informal

Depth

Rockwell

Macro

500 to 3000 kgf

5, 10mm Ball

E103

Depth


Microhardness

Vickers

5 to 1000 gf

136° Pyramid Diamond

E 384

Area

Microhardness

Knoop

5 to 1000 gf

130° x 172° Diamond

E 384

Area

Microhardness

Rockwell

500 gf to 30 kgf

Truncated Cone Diamond

Informal

Depth


Brinell

Optical

62.5 to 3000 kgf

5, 10mm Ball

E 10

Area

Brinell

Depth

500 to 3000 kgf

5, 10mm Ball

E103

Depth