Chemical Machining is a very well known, nontraditional machining process. It is the controlled chemical dissolution of the machined work piece material by contact with a strong acidic or alkaline chemical reagent. Special coatings called mask ants protect areas from which the metal is not to be removed. This process is used to produce pockets and contours as well as remove materials from parts that have a high strength-to-weight ratio. Furthermore, the chemical machining method is commonly used to produce micro-components for several industrial applications such as micro electromechanical systems and semiconductor industries.
As a nontraditional and significantly old methodology, chemical machining had been used since ancient Egypt to shape copper with citric acid. Until the 19th century, however, this process was widely used for decorative etching. The process and advancement in photography made way for a new dimension to chemical machining and in the mid-19th century J.N. Niece was the first to use a photo resist made from bitumen of Judea asphalt for etching pewter though, the main industrial implementation of chemical machining did not develop until after the Second World War.
Chemical machining has been used for centuries and there are several factors to its wide and popular use: the process is mature and well established, it is extremely simple to implement, there is no additional cleaning after completion and it is relatively cheap compared to other processes. Not only is chemical machining used to produce complex machine parts for various applications but decorative parts as well. However, there are many environmental issues in the operations of chemical machining. Most chemicals like the, etchants and strippers used during chemical machining are hazardous liquids, therefore the disposal of them is very costly. The industrial trend is to use and select environmentally safe chemicals for the machining process, thus environmental laws play a significant role when the chemical machining process is used.