Invar, also known as FeNi36, is an iron-nickel alloy with a low coefficient of thermal expansion. It is ideal for applications where dimensional stability is required, such as in optical and electronic devices. Invar can be machined using conventional CNC methods, but special care must be taken to avoid cracking and warping. In addition, due to its high melting point, Invar can be difficult to weld.

CNC machining is a subtractive manufacturing process that uses computer numerically controlled (CNC) machine tools to remove material from a workpiece to create the desired shape. Invar is an excellent material for CNC machining due to its high strength and low expansion properties. The dimensional stability of Invar makes it ideal for applications where precise dimensions are critical, such as in aerospace engineering and metrology.