The most common metal used in CNC (Computer Numerical Control) machining processes is aluminum. Aluminum is widely used in CNC machining due to its favorable characteristics such as being lightweight, relatively easy to machine, and having good corrosion resistance. It is commonly used in various industries, including automotive, aerospace, electronics, and general manufacturing. Other commonly machined metals include steel, stainless steel, brass, and copper, but aluminum tends to be the most prevalent material in CNC metal machining.