This document explores the differences between CNC milling and electrochemical machining (ECM), two methods of material removal in manufacturing. While both are used to create complex shapes and features on metal parts, they use different techniques to achieve this. CNC milling is a subtractive manufacturing process that uses computer-controlled machines to remove material from a workpiece, while ECM is a non-traditional machining process that uses electrolysis to remove material from a workpiece. Each process has its own advantages and disadvantages, and the choice of process will depend on the specific requirements of the part being produced.