Photochemical Machining
Blanking
Photochemical machining (PCM) allows burr-free, stress-free blanking on virtually all ferrous and nonferrous metals with no chemical or physical alteration to the materials. With precise multiple imaging, multiple parts blanks can be produced on sheets up to 30 in. wide. The process can work with metals of any temper with thickness ranging from 0.001 in. to heavy gauge. The tolerance range is ±0.001 to ±0.010 in., depending on material type and thickness. See Figure 1.26 for some examples of parts made by this process.
The process starts with CAD drawings, either furnished by your company or made by the supplier. This is then copied multiple times to make a master negative containing the total parts required in the initial order, and checked for accurate registration. A metal sheet is sheared to size, cleaned, and coated with a photoresist. A contact print is made from the master sheet, and developed. The entire sheet is then immersed in an acid bath and the unwanted metal is "eaten" away, leaving the finished part. The photoresist is then removed. This can then be followed by machining, forming, or whatever subsequent process is required.
Forming and Fabrication
Many companies offer complete photochemical engineering services, using state-of-the-art computer-aided design. Precision plotting and photographic equipment allow for the design of complex and intricate parts with economical photo tooling costs. In general. these companies are very willing to work with your design team to bring your concept to production quickly and accurately. Because tooling is produced photographically, lead time can be reduced from weeks to hours, and design changes can be made quickly, without scrapping expensive dies. Typical lead time is 1 to 2 weeks using readily available materials, but this time can be shortened if the schedule demands it. An example of a firm with a complete in-house tooling, forming, and fabrication department, Microphoto, Inc. (Detroit, Michigan), can economically produce quality finished parts. Using both mechanical and hydraulic presses, they produce precision parts to most print tolerances after PCM blanking.

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