The material hardness is one of the properties of a material, refers to the stiffness or resistance to plastic deformation by penetration and indentation, bending, scratching, machining, wear, yielding, abrasion or cutting. Hardness allows the metal to resist being permanently deformed when a load is applied. The harder the material is, the greater the resistance it has to deformation, which means the less likely it is to deform.
Due to the multiplicity of hardness definitions and measuring instrument, the hardness is more likely to be a composite property of a material, reflects yield strength, tensile strength, modulus of elasticity and more, while not a single feature. When choosing a material or cutting tool to produce CNC machining parts, hardness should be considered.