2.1 Brief Review Over Metal Cutting History >The first cutting tool used by mankind: Broken bone Splintered flint(带锐角燧石) The search to find better tool materials and more efficient cutting methods started ever since.2.1 Brief Review Over Metal Cutting History The first cutting tool used by mankind: • Broken bone • Splintered flint(带锐角燧石）. The search to find better tool materials and more efficient cutting methods started ever since