Photo Chemical Milling
Photo chemical milling also referred to as photo etching uses corrosive chemicals on sheet metals to effectively remove certain areas of material. It became popular in the 60’s due to the circuit board market which was growing exponentially at the time. It has been commonly compared to another, similar process call photolithography, which uses light sensitive materials and metal just like the chemical milling method.
The photo chemical milling process is used to produce complex parts with extremely fine detail economically and accurately and is markedly cheap than using an alternative such as punching, laser, stamping or waterjet. The tooling needed is cheap and easily produced.
It is a favorite of the mass production field due to its easily changeable set-up. Also, no burring or burns result from such a process so production costs can be drastically reduced and the chemical process can be safely and effectively applied to any metal or alloys available. To kick off the process a clean image of the part is photo filmed on to the material. After being vacuum sealed together the film and the metal plate are laminated together and exposed to amounts of UV light which fuse the two together.
The etching line machine is full of an acid solution that when sprayed on the non- covered areas of the metal sheet will result in pattern etchings. The chemical ferric chloride is commonly used in the photo chemical milling market. The acid reacts with the metal corroding away any un-filmed parts. After neutralizing the acid chemicals the part is ready for further manufacturing. One draw-back to the photo chemical milling process is that it can only be applied to thin gauged materials, preferably under .050 of an inch. Applications I this process include, but are not limited to; sensors, battery grids, fuel cells and jewelry.
This method of production remains in-expensive and quick. Nearly all photo chemical milling equipment can be purchased for less than $350 and can take less than 2 days to make. Less money is also spent on up keep seeing that no moving parts, such as dies and molds, are present no wear and tear takes place. The materials best suited to such chemical processes include, brass, copper, aluminum, nickel, silver, steel, stainless steel and titanium. When the pieces for production are super sensitive and delicate, like computer boards and electronic equipment, photo chemical milling is the only way to go.