The Photochemical Machining Process

Photochemical machining (PCM) is a highly precise, chemical-based method for producing complex metal parts. By combining advanced phototools, specialized photoresists, and controlled chemical etching, this process allows Switzer Manufacturing to produce intricate components with excellent dimensional accuracy, burr-free edges, and minimal material stress. PCM is ideal for designs with fine detail that would be difficult or costly to achieve using traditional machining or stamping methods - or for any component that demands exceptional precision. 

Photochemical machining, also called photochemical etching or simply chemical etching, is a precision process that uses a photoresist tool and chemical etchants to selectively remove metal from sheet stock to create your parts.

The result is complex, burr‑free metal components with excellent dimensional control. Compared to conventional mechanical cutting, stamping, or laser/water‑jet operations, PCM offers a low‑stress, no‑burr alternative, ideal for thin metals and intricate geometries.

Chemical etching produces precision metal components accurately and quickly. The process is scalable and is suited for prototyping through production volumes. Animation courtesy of the Photo Chemical Machining Institute.

Your part begins as a CAD drawing, which is converted into a phototool - a high-resolution negative of the part pattern printed onto stable, transparent film. This film acts as a stencil for etching your components. These film tools are fast, inexpensive, and easy to revise for design changes, making prototyping and test runs far lower risk than hard tooling processes.

Sheet metal of the appropriate alloy and thickness is selected based on application requirements. Metals commonly used include stainless steel, copper, aluminum, and nickel alloys. The metal is cut to size and thoroughly cleaned to ensure proper adhesion of the photoresist.

The cleaned metal sheet is coated with a UV-sensitive photoresist. The phototool is aligned and pressed in a vacuum frame to ensure complete and seamless contact. The resist is then exposed to ultraviolet light, which hardens the resist in the clear areas, while the unexposed areas are washed away. This exposes the metal to be etched, and creates the etching template.

After imaging, the exposed photoresist is developed to selectively remove the film in the unhardened areas, precisely defining the etch pattern on the metal surface. This step reveals the exact geometry to be etched while maintaining tight dimensional control and feature fidelity.

The developed metal is passed through a controlled chemical etching process that removes material only where the photoresist has been cleared, creating highly accurate, burr-free features. Etch chemistry, time, and temperature are tightly controlled to achieve consistent depth, clean edges, and repeatable results across the entire part.

After etching, the remaining photoresist is stripped away and the parts are cleaned to meet surface and dimensional requirements.

Etched parts can undergo secondary operations such as forming, plating, welding, or integration into larger assemblies to meet final application requirements. These value-added processes allow PCM components to transition seamlessly from precision-etched parts to fully functional, production-ready solutions.

Throughout the process, strict quality control measures ensure dimensional accuracy and consistency. PCM produces stress-free, burr-free parts with tolerances as tight as ±0.001" for thin materials, maintaining the full integrity of the metal. Various Quality Control tools are used to thoroughly inspect components for precision, accuracy and uniformity.