content: You're right that the oxygen doesn't burn on its own and makes the acetylene burn hotter, but it is in fact the oxygen that cuts the metal. With oxy-fuel cutting, you don't actually heat the steel until it melts; the high pressure stream of oxygen combines with the iron to form Iron Oxide, which has a lower melting temperature than the surrounding metal (which is subsequently blown away by said oxygen stream). That's why you end up with such a nice clean, defined cut if you do it right