Photochemical machining (PCM), which is also called photochemical milling or photo etching, is a process that uses chemicals to fabricate sheet metal components. A photoresist is used to mask the metal while chemical etchants corrosively machine the untreated areas. At Faspro we use photochemical milling to produce very complex parts with fine detail. The accuracy of the process and its low cost make it attractive for prototype and short run production.
How Photochemical Machining Works
We start the process with the shape of your fully designed part. In some cases we help finish the design or offer suggestions that will work better with photochemical milling. The part is then traced and cut from photographic film which is called the register, the base part of the tool. Metal is cleaned and processed with a UV-sensitive photo-resist, then placed between two sheets of the phototool and placed in a vacuum to ensure contact between the metal and the film. The tool is then exposed to UV light and where the film was cut away, the light hardens the photoresist and where the film blocks the light, it is washed away. Areas of the metal not covered by the photoresist are now unprotected.
During etching a chemical solution is forced under pressure to both sides of the part and in the unprotected areas, the etchant hits the metal and immediately starts corroding the metal. In some cases, we can etch to a depth for a partial break or we can etch completely through the metal to make a pocket or to separate parts on the sheet. The metal is then neutralized and cleaned, and the parts on the sheet are ready for the next step in processing.
How Photochemical Milling is Used
Photochemical milling is an economical alternative to laser-cutting, water jet cutting or EDM machining for thin gauge parts. It can also be used in place of traditional stamping, punching, or other forming methods to create precision parts. The low cost of tooling and relative ease of making tooling changes make photochemical milling perfect for prototyping and mass production alike. The process is very accurate and since less stress is introduced into parts during machining they maintain dimensional accuracy and have superb surface finish. In some cases we can make parts in hours rather than days or weeks.
Types of Metal
Almost any metal at any hardness can be photomilled. Normal thicknesses of between .004″ and .040″ are common, but we are capable of working with thinner or thicker stock. The metals that we normally use in photomilling include:
For more information on Faspro Technologies’ photochemical milling capability, please contact us.
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