A method of measuring the hardness of metal parts and hard seal faces.

In this test a hardened steel ball is forced into the material at a given pressure. The width of the depression then becomes the measure of the material’s hardness.

Because the ball deforms on very hard surfaces, this test is somewhat limited in its use.

Above a number of 350 the standard machining operations of turning, boring, drilling, and tapping become uneconomical.

You can compare a Brinnell reading to the following file readings:

100 – Metal removed easily by the file.200 – Slightly more pressure needed to remove metal.

300 – Metal shows resistance to the file.

400 – Takes more pressure on the file.

500 – File removes almost no metal.

600 – Metal cannot be filed.