What is the term for the flame's inner cone in oxyfuel cutting?

In oxyfuel cutting, the term for the flame's inner cone is referred to as "the feather." This part of the flame is crucial as it is where the combustion of the gas occurs and represents the hottest point of the flame. The feather produces a very concentrated heat, which is necessary for effectively melting and cutting through metal. A well-defined feather indicates that the oxyfuel torch is correctly set up, with the right balance of oxygen and fuel gas, leading to optimal cutting performance.

The other terms, while they may describe different aspects of the flame or cutting process, do not specifically highlight the inner cone which is essential for the effectiveness of the cut. A proper understanding of the feather's role in the oxyfuel cutting operation is key for anyone working with this process.