The Basics of Measuring Hardness

A hardness scale measures material's hardness in terms of its capacity to resist a minor load, typically three kilograms of force. A diamond-tipped cone is pressed into the material at two levels of pressure. The numbers from the cone are translated to HRC using a formula. The process can leave a mark on the material, so many makers use special scales to measure case-hardened specimens. Listed below are the basic steps of measuring hardness.

Type C numbers are commonly used for kitchen knives. These numbers range from HRC52 to HRC60. Kitchen knives, for example, should have a hardness of around HRC57 or higher, as anything lower than this is too soft to be used for cutting food. A good example of such a steel is 8Cr13MoV, which is hardened to an HRC of 57-59. This steel performs admirably in this range.

Although most kitchen knives are designed to be durable, a lower HRC rating may not mean a high quality knife. Generally speaking, kitchen knives that fall in this range will be easily sharpened, but may not hold an edge very well. In comparison, a high-HRC blade is brittle and not suitable for daily use. To determine if an HRC 55 is appropriate for your needs, consider the materials used in the knife.

An HRC55 end mill bit has a strong adaptability to the material it's used to cut. Most commonly, it's used for steel parts made from carbon steel, cast iron, and high-hard steel, including 9crsi die steel. It also has high chip removal. The hardest of the three grades is HRC55, and HRC60 and HRC65 are available for hardnesses between 60 and 65.

The hardness of the material is measured on the Rockwell hardness scale, abbreviated as HRC. Soft materials have an HRC of 52, while harder materials have higher HRCs, like stainless steel or titanium. The HRC55 long neck ball node end mill is bronze coated and is made from super raw materials, including Kennametal Metal, Sandvik Carbide, CB Carbide from Taiwan, and TiSiN Coating. This quality coating increases tool life and improves its durability. The blade is usually stamped with the number to help identify its quality.

A high-quality knife with a HRC of 55 will be durable, but may be brittle and require more work to sharpen than a lower-quality knife. HRC 55 knives are easy to sharpen, but will not hold an edge as long as those with lower HRCs. Stainless steel with a HRC of 55 or above is commonly used for professional German kitchen knives. These types of knives will retain their sharpness for a long time. They should be sharpened on a sharpening steel periodically to ensure they maintain their sharpness.