By definition hard turning is performed on steel with hardness values of 45 Rc or above, and typically in the 60 – 68 Rc range. This method has a number of advantages for manufacturers including the elimination of specialized grinding equipment and the ability to perform multiple CNC machining operations with one setup. As a result, you reduce your machine tool investment and labor costs-per-part while improving throughput. All of which means greater productivity and profitability.
Machining success depends largely on component rigidity, the geometry to be turned, lathe rigidity, and vibration damping characteristics. Rigidity is critical for successful hard turning. The rigidity of tooling, workholding, and the machine tool itself are all crucial elements that will affect your ability to successfully hard turn. Hard turning is a technology-driven process, dependent upon:
When considering hard turning, the question is not “Can it be done?” because many machine tools can hard turn. Instead the question is, “How well can it be done?” Success in hard turning is largely a measure of the machine construction and design along with the workholding and tool holding. The level of rigidity and damping in a hard turning application cannot be minimized. That’s where Hardinge has a competitive advantage.
Grinding does–and likely always will–have a place in manufacturing, as all components can not be hard turned due to tolerance requirements and the surface integrity of the part.
Hard turning is defined as the process of single point cutting of part pieces that have hardness values over 45 Rc.