Photochemical Machining Process / /
Step 1: Tooling
A photo plotter is used to create a photo tool which is a negative image of the part. The part is nested to maximize the number of parts per sheet. Two laminates are printed, one each for the top and bottom of the metal sheets.
Because each photo-tool is a made of film, tooling can be finished in just hours and at a far lower cost than required by other machining methods. Additionally, these qualities ensure that part designs can be changed and applied to production exceptionally fast.
Step 2: Cleaning
Proper metal preparation, degreasing, and the removal of surface contaminants is essential for proper adhesion between the raw material and the photoresist during the coating process.
Modern PCM companies have invested in “clean lines” for improved material cleanliness. These conveyorized machines are typically multi-chambered and material is put through a series of cleanings and rinses to ensure proper surface condition.
The quality and quantity of the finished parts depends greatly on the care taken during this step.
Step 3: Coating
The material is coated with photoresist directly after cleaning which reduces the chance of surface contamination and oxidation. The coating is photosensitive and resistant to the etchant used to cut the chosen metal. Dry film or liquid resist is applied to both sides of the work piece to allow etching for both sides simultaneously.
Advances in resist technology combined with new and improved Computer Assisted Design (CAD) artwork have enabled photoresist coatings to accommodate extremely complex features.
Step 4: Exposing
During this step in the photo etching process, material with the photosensitive coating is exposed to UV light. This is a straightforward process that transfers the photo tool image onto the coated material.
The metal is put into the double-sided photo tool and is exposed to UV light on both sides, an image is formed in the photoresist. This then becomes a durable image on both sides of the metal.
Step 5: Etching
Virtually all metals can be etched, although some are etched more readily than others. Most metals can be etched using a relatively innocuous etchant, an aqueous solution of ferric chloride.
First, the metal is rinsed of the remaining photoresist that hasn’t bonded to the metal. Then, etchants are applied to the metal in a conveyor machine. During this process, the non-bonded areas of metal are exposed to the etchants and begin to etch upon contact.
Because etchants are applied to the entire sheet of metal at once, PCE maintains the unique ability to make every cut simultaneously, which can save countless hours for parts with complex geometries or features, and especially for fine meshes and screens.
Step 6: Finishing
The next step in the manufacture of chemically etched parts is stripping off the protective coating of photoresist. Many companies use machines that have a strip chamber on the etch machines to increase efficiency.
Now your part is finished! Or is it?
Parts often require secondary processes or treatments post-blanking before they are finished and ready to be shipped. Luckily, Fathom can take care of that.
We offer a wide range of services including heat treatment, plating, and precision forming through partnerships with local treatment firms and our sister companies.