Machined and Industrial Generated
Introduction
Wet chemical attack also known as chemical milling is a material removal technique, which is based on the elimination of unwanted material by attack with an active chemical substance, such as an acidic or alkaline aqueous solution "Base (chemistry)"). The parts that are not intended to be attacked must be protected with insulating coatings. By modifying these isolations between attacks, different geometries can be achieved, as well as greater depths if done in several steps.
History
Wet chemical attack may be one of the oldest unconventional etching methods, since the Egyptians, in the year 2300 BC, were already using it to shape copper through the use of citric acid. Since then, it is a process that has constantly evolved, reaching its use in decorative engravings until the century. Subsequently, one of the greatest constructive contributions to the process was produced thanks to photolithography, a discipline in which photosensitive materials began to be used to record on tin-lead alloys. The main application today is in the electronics industry, as well as in aeronautics and microelectromechanics.
Description
The removal of material can be carried out by immersion in the attacking substance, or by simply spraying it.
It is a process suitable for large surfaces, such as "Wing (aeronautical)" wing coatings, since the attack occurs as a function of time, regardless of the extent of the part. Although the machining speeds achieved are not very high, there is the advantage of being able to attack the entire piece at once. For this reason, it would take the same time to machine a small part, such as a printed circuit board, as a large part such as a satellite panel.
The time that the piece is immersed in the corrosive solution is, therefore, the factor to control since the amount of material removed depends on it. It is observed, however, that the activity of said substance decreases as time progresses, which is partially alleviated by shaking it in order to renew the active substance in the attack areas. Furthermore, to achieve better evacuation of the removed material residues, the pieces are usually arranged in a vertical position, since by gravity these remains will be deposited at the bottom of the immersion bucket.