Rockwell Hardness Tester

Rockwell Hardness Tester

Owner/Loaner	PS:One
Serial Number	4MM 344
Make/Model	4M
Arrival Date	Summer, 2015
Usability	yes
Contact	Host Cold Metals
Where	Cold Metals, on a bench
Authorization Needed	yes
Hackable	no
Estimated Value	$500
Host Area	Cold Metals

Qualified Member	Trained By
NA	Danger committee

Rockwell Hardness

The Rockwell scale is a hardness scale based on indentation hardness of a material. The Rockwell test determines the hardness by measuring the depth of penetration of an indenter under a large load compared to the penetration made by a preload. There are different scales, denoted by a single letter, that use different loads or indenters. The result is a dimensionless number noted as HRA, HRB, HRC, etc., where the last letter is the respective Rockwell scale. When testing metals, indentation hardness correlates linearly with tensile strength. This important relation permits economically important nondestructive testing of bulk metal deliveries with lightweight, even portable equipment, such as hand-held Rockwell hardness testers.

Copied from Wikipedia. See Wikipedia for additional background

Operation

Select the correct indentor - diamond for HRC other material for HRC

1) Install indentor
2) Support load
3) Place component on anvil, use a specialized anvil if needed ( eg. round stock)
4) Turn handwheel 

Typical values

• Very hard steel (e.g. chisels, quality knife blades): HRC 55–66 (Hardened High Speed Carbon and Tool Steels such as M2, W2, O1, CPM-M4, and D2, as well as many of the newer powder metallurgy Stainless Steels such as S30V, CPMS-154, ZDP-189, etc.)
• Axes: about HRC 45–55
• Brass: HRB 55 (Low brass, UNS C24000, H01 Temper) to HRB 93 (Cartridge Brass, UNS C26000 (260 Brass), H10 Temper)

Several other scales, including the extensive A-scale, are used for specialized applications. There are special scales for measuring case-hardened specimens.

Notes

As of October 2015, the machine shop doesn't have a diamond indenter for the Rockwell C scale -- but we do have spherical indenters for Rockwell B.

Keep the dust cover on. Use calibration discs if you care about your results. Accessories for the tester are in the tan colored cabinet.

Resources

Wikipedia : https://en.wikipedia.org/wiki/Rockwell_scale

This video shows another machine but it has a good explanation of the test: https://www.youtube.com/watch?v=G2JGNlIvNC4

Again a different machine but shows procedure : https://www.youtube.com/watch?v=3FX3wFhk0mQ

Source for diamond indentor: http://www.westportcorp.com/dpc1.html